A Taxonomic and Ecologic Study of the Riverbottom Forest on St. Mary River, Lee Creek and Belly River in Southwest Alberta, Canada

Brigham Young University BYU ScholarsArchive

Theses and Dissertations

1974-08-01

A taxonomic and ecologic study of the riverbottom forest on St. Mary River, Lee Creek and Belly River in southwest Alberta, Canada

Robert Keith Shaw Brigham Young University - Provo

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BYU ScholarsArchive Citation Shaw, Robert Keith, "A taxonomic and ecologic study of the riverbottom forest on St. Mary River, Lee Creek and Belly River in southwest Alberta, Canada" (1974). Theses and Dissertations. 7976. https://scholarsarchive.byu.edu/etd/7976

This Dissertation is brought to you for free and open access by BYU ScholarsArchive. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. f fO L2- ol 'tJ A TAXONOMICAND ECOLOGIC STUDY OF THE RIVERBOTTOMFOREST ON ST. MARYRIVER, LEE CREEKAND BELLY RIVER

IN SOUTHWESTALBERTA, CANADA

A Dissertation

Presented to the

Department of Botany and Range Science

Brigham Young University

In Partial Fulfillment

of the Requirements for the Degree

Doctor of Philosophy

by I Robert Keith Shaw

August 1974 ACKNOWLEDGEMENTS

The author wishes to extend his thanks to all those who have

helped make this work possible. Gratitude is expressed to Dr. S. L.

Welsh, Dr. J. R. Murdock and Dr. C. Lynn Hayward of Brigham Young

University for their counsel and guidance during the course of this

study. The use of the Herbarium of Brigham Young University and the

assistance rendered by its curator, Dr. S. L. Welsh, in identifying

plant specimens are gratefully acknowledged.

The author also wishes to express his appreciation to his wife Shirley and his brother Mike for being a very willing field

crew during the study.

iii TABLEOF CONTENTS Page ACKNOWLEDGEMENTS...... •• iii LIST OF TABLES•• ...... V LIST OF FIGURES . vii INTRODUCTION...... 1 GEOLOGYAND GEOGRAPHY ...... 8 CLIMATE ...... 15 LITERATUREREVIEW ...... 20 METHODSAND MATERIALS ...... 25 RESULTS

General Features of River Valleys and Riverbottom Forest •• . . 32 The Climax Forest 45 Taxonomic Treatment ...... 88 KEYSAND DISTRIBUTIONS 90 DISCUSSION• • 191

SUMMARYAND CONCLUSIONS • 209 LITERATURECITED...... • 213

iv LIST OF TABLES

Table Page

1. Mean monthly streamflow in cubic meters per second of St. Mary Riyer, Lee Creek and Belly River in southwest Alberta, Canada •••••••••••• . . . 4 2. Mean monthly precipitation in centimeters and inches for Cardston, Alberta; elevation 1151 meters •• 5

3. Mean daily temperature in degrees Centigrade and degrees Fahrenheit at Cardston, Alberta ••• 16

4. Results of the mechanical analysis of soils sampled at 9 sites occupied in part by a pioneer riverbottom forest community and in part by a sandbar willow community • • • • • • • • • • • • • • • 35

5. Percentage of the valley cross-section occupied by mature riverbottom forest at the 10 study sites in southwest Alberta • • • • • ••••• 40

6. Mature tree stratum data from 10 riverbottom forest stands in southwest Alberta. • • • • • ••• 47 7. Tree reproduction data from 10 stands of mature riverbottom forest in southwest Alberta ••• 49

8. Clumped shrub data from 10 mature riverbottom forest stands in southwest Alberta •••••••••••••• 52

9. Thicket shrub data from 10 mature stands of riverbottom forest in southwest Alberta ...... 54 10. Herbaceous vegetation data from 10 mature stands of riverbottom forest in southwest Alberta ••••• 57

11. Summary of herbaceous species stand dominants based on a minimum importance value of 7.5 or more in at least one stand • • • • • • • • • • • • • • • 64

12. Unoccupied space (rock, litter, bare soil) in 10 stands of mature riverbottom forest measured at the herb stratum level •••••••••• . . . . . 66

V Table Page

13. Community similarity and dissimilarity totals for the 10 stands in the riverbottom forest community of southwest Alberta· ••••••••••••• 68

14. Penetrometer readings from ten mature stands of riverbottom forest in southwest Alberta. • ••••• 71

15. Summary of soils analyses (Bouyoucos, 1936) for 10 mature stands of riverbottom forest, adjacent gravel bars and fescue prairie grasslands in southwest Alberta. • • • • • • • • • • • • • •• , 72

16. Average diameter and age, and largest diameter and age, of mature trees in 10 stands of riverbottom forest in southwest Alberta ••••••••••••••• 74

vi LIST OF FIGURES

Figure Page 1. Streams of southwest Alberta, Canada ...... 2 2. Subsurface geological strata in southwest Alberta 10

3. Study sites on St. Mary River, Lee Creek and Belly River in southwest Alberta • . • • • • • • • • • 26 4. St. Mary River 3 kilometers downstream from the St. Mary Dam • • • • • • • • • • • • • • • • • • 33 5. Site 4 - Woolford Park, a typical riverbottom forest stand on the second terrace of St. Mary River. 33

6. A pioneer riverbottom forest stand before 3 days of over-site flooding •••••••••••••• 37

7. The same gravel bar after 3 days of over-site flooding ...... 37

8. Site 1 - Cook's Ranch on St. Mary River. 38

9. Site 5 - Town Dam on Lee Creek 38

10. Valley profiles for three stands of mature riverbottom forest in southwest Alberta •••••• . . . . 39 11. A climax riverbottom forest stand on St. Mary River. 42

12. Kearl Ranch picnic grounds on Lee Creek. 42

13. The Woodgrove Park area on St. Mary River ••••• 43

14. Similarity and dissimilarity coefficients between ten stands in the riverbottom forest community of southwest Alberta • • • • • • • • • • • 67

15. Populus angustifolia X balsamifera, dbh 129 cm and approximate age 200 years ••••••• 77

16. Populus angustifolia X balsamifera at Woodgrove Park, St. Mary River ••••••••••• 78

vii Figure Page

17. Composite of mean monthly precipitation, temperature and streamflow correlated with important riverbottom forest events ••••••••••••••• 79

18. Tree leaf-out at Site 4 - Woolford Park in May, 1972 82 19. Faintly visible in the grass are several large stones set in the form of a circle, the "tepee ring~' of the plains Indians ••••••••••••••• 82 20. Beaver utilization.of the riverbottom forest ct Site 5 - Town Dam on Lee Creek •••• . . . . . 86 21. Successional schema for the riverbottom forests of southwest Alberta, Canada. • • • • • • • • • ••• 199

viii INTRODUCTION

The riverbottom forest community of southwest Alberta, Canada is usually less than 0.8 km in width and occurs on only certain lengths of each stream. It has been utilized for pasture and to a minor extent for firewood and timber, leaving much of the woodland free from excessive disturbance. Many sites along the streams give good indication of the natural composition and appearance of the riverbottom forest. At other places successional trends on gravel bars and stream banks are evident. Detailed taxonomic and ecologic studies are lacking for this community. This study treats several aspects of the riverbottom forest community including the vascular flora, community stratification and composition, successional patterns, seasonal aspect, climate, geography, geology and soils.

The St. Mary River, Lee Creek and Belly River originate in alpine tundra (elevation 2,000 - 3,200 meters) on the Lewis Range of the Rocky Mountains in Glacier National Park, Montana (Figure 1).

From alpine tundra these streams flow northeast into the Province of

Alberta, Canada through montane forest and aspen parkland into the treeless stretches of fescue prairie (elevation 900 - 1,400 meters) where, along the stream courses, the poplar-dominated riverbottom forest community becomes a unique ecological entity.

St. Mary River drains about 3,440 square kilometers, Lee Creek about 290 square kilometers, and Belly River about 1,235 square kilometers of northwest Montana and southwest Alberta. 2

Porcupine Hills 1580 m

17 km

• Standoff

Belly River Waterton

Mary Reservoir 1113 m

• Mountain St. Mary View Lee Creek River 1312 m Milk River Ridge 1433 m _A.l!?.e'tl_a '-C~adJL _ Montana, U.S.A.

Lewis Range 3200 m

Figure 1. Streams of southwest Alberta, Canada. 3

St. Mary River originates at St. Mary, Montana where the river flows from Upper St. Mary Lake to Lower St. Mary Lake having accumulated water from glaciers, snowbanks, lakes and streams draining some of the most scenic parts of Glacier National Park. From Lower

St. Mary Lake it flows northward picking up more water from the Many

Glacier and Kennedy Valleys. It crosses the International Boundary at

Alberta Township 1, Range 25 where ic also leaves the aspen parkland and begins a northward traverse of the fescue prairie grassland and ultimately the mixed prairie grassland before it discharges into the

Oldman River near Lethbridge, Alberta at Township 8, Range 22.

Lee Creek originates on the north and east slopes of Old Chief

Mountain in Glacier National Park and adjacent Blackfeet Indian Reser- vation, Montana. It flows from alpine meadows in three branches which join where the creek crosses the International Boundary into Alberta at Range 27. Lee Creek flows northeast, emerges from aspen parkland into fescue prairie grassland near the hamlet of Beazer, continues to the town of Cardston and discharges into St. Mary River 3.2 km below the town at Township 3, Range 25.

Belly River (a translation from the earlier French name "Gros

Ventre") begins in a series of lakes in northern Glacier National Park, flows through spectacular s~enery to the International Boundary at

Alberta Range 28. Several kilometers directly west of the hamlet of

Mountain View it emerges from aspen parkland and enters fescue prairie grassland. It flows northeast to Standoff, Alberta where it merges with the Waterton River. The two merged rivers continue as Belly

River northeast, discharging into Oldman River near Monarch, Alberta.

Oldman River is part of the South Saskatchewan system and ultimately 4

these waters drain into Hudson Bay.

Monthly water flow in all three streams varies widely through-

out the year (Table 1). From late July through autumn and winter the

flow is fairly constant but during March warmer weather causes snow

melt in the foothills and on the lower mountain slopes to increase

stream flow. The most rapid melting of deep mountain snow occurs in late May and early June. This coincides with the season of highest

precipitation (Table 2), swelling stream flow to its maximum which is four to five times the winter flow rate. Stream flow generally peaks

rapidly in late May or early June followed by a rapid decline through-

out July. Maximum flow in any year seldom persists for more than

twenty four hours.

The St. Mary River normal flow is modified by the Sherburne

Table 1. Mean monthly stream flow in cubic meters per second of St. Mary River, Lee Creek and Belly River in southwest Alberta, Canada.

St. Mary River Lee Creek Belly River Month Kimball Cardston Mountain View

January 4.8 0.4 2.0 February 4.6 0.4 2.0 March 6.0 1.1 2.0 April 15.5 2.4 6.6 May 50.4 4.6 21.5 June 78.4 4.5 28.8 July 41.4 1.5 16.0 August 19.2 0.5 7.4 September 15.2 0.5 5.2 October 13.9 0.6 5.2 November 10.4 0.5 3.8 December 6.1 0.3 2.3 5 Dam on Swiftcurrent Creek and the St. Mary Canal at Babb, Montana which take water from the river and move it across the Hudson Bay

Divide into Milk River of the Missouri River drainage system for agricultural use in northern Montana. From 1903 until the late 1940's the Alberta Railway and Irrigation Canal took much of the summer flow from St. Mary River at Kimball, Alberta to irrigate land in the Lethbridge area. This project was abandoned by 1950 after the comp- letion of the St. Mary Dam and Canal at Spring Coulee, Alberta and the filling of the reservoir. St. Mary Reservoir is capable of reducing flow in the lower half of that river to less than flood level at any season.

Table 2. Mean monthly precipitation in inches and centimeters for Cardston, Alberta; elevation 1,151 meters.

Month Inches Centimeters

January 0.75 1.9 February 0.91 2.3 March 1.14 2.9 April 1.39 3.5 May 2.38 6.1 June 3.59 9.1 July 1.62 4.1 August 1.50 3.8 September 1.75 4.4 October 1.19 3.0 November 0.94 2.4 December 0.88 12.2

Total 18.04 45.8 6

The town of Cardston (population 3,000) takes its municipal water from Lee Creek by means of a small diversionary dam and pipeline several miles above the town.

Belly River has three water diversions along its length. The

United Irrigation District began diverting water in 1922. The

Mountain View diversion began to tap the river near the Montana border in 1923. Just below Hillspring a recently completed diverRion takes much of the remaining summer flow from the river and moves it by canal across the Blood Indian Reservation to St. Mary Reservoir.

In spite of these uses, near normal flow does prevail in the three streams in all months of the year except July, August and

September. Irrigation water is in low demand at the high runoff season and dams and diversions exert little control on downstream flooding.

Several small recreational parks and campgrounds have been developed along the streams. Annual high water is a yearly threat to park maintenance. Few town or ranch buildings have been placed within riverbottom forest because of flood danger. Fort Macleod, built by the North West Mounted Police in 1874 on an island in riverbottom forest on Oldman River, had to be abandoned after flooding. Later it was rebuilt on nearby higher ground. The St. Mary Crossing detachment of the North West Mounted Police was rebuilt as many as three times in fifteen years because of flood damage and was finally moved out of riverbottom forest to higher ground.

Pollution of the waters vary. No industrial wastes reach these streams. Municipal sewage· and some agricultural feedlot effluent cause local problems. Early snow melt combined with percolation and 7 leaching of water through old vegetation and manure on the uplands causes discoloration and objectionable odor in the water during March and April of each year. High runoff from rain and melting snow in late

May and early June produces a high particulate content in the water at this time. For the rest of the year stream water in St. Mary River,

Lee Creek and Belly River tends to be clear, clean and free from contaminants. GEOLOGYAND GEOGRAPHY

The headwaters of the three streams originate on the Continen- tal Divide over geological formations of the Belt Series in the Lewis

Range of the Rocky Mountains (Wyatt, 1939). These strata, nearly all of sedimentary origin, were formed during the Proterozoic Era of

510,000,000 years ago when much of western Alberta, eastern British

Columbia, Montana and Idaho were covered by a shallow sea. These rocks, with a maximum thickness of more than 6,100 meters, are in the form of a large syncline the east edge of which forms the Lewis Range.

Many of the rocks show mudcracks and ripple marks. The greatest thicknesses of limestone show numerous fossils of calcareous algae and primitive marine plants.

The mountains themselves, of more recent origin, are about

58,000,000 years old. They resulted when tremendous crustal forces, principally from the west, were directed against the geosyncline. The

Proterozoic rocks were uplifted and moved some 80 kilometers to the east where they were warped into a great anticline, the Lewis Over- thrust, which overlies the younger Cretaceous shales and sandstones of the plains. It is because of the Lewis Overthrust that there are no significant foothills on the east side of the Lewis Range.

During Miocene and Pliocene time the mountains were deeply eroded by streams. Several thousand meters of Belt rocks were removed during the course of valley formation. Near the close of Pliocene time the climate cooled, vegetation disappeared, mountain glaciers 9 formed from the snow and began to move down the stream-carved valleys where they met the continental glaciers advancing from the north.

The prairie section of St. Mary River, Lee Creek and Belly

River flows through and over a variety of consolidated and unconsol-

idated deposits, from the transported Belt series rocks of Proterozoic

time to the more recent Cretaceous series. The geological formations which occur at the surface or immediately below the unconsolidated deposits in the plains and foothills zone of southwest Alberta are

Cretaceous and Tertiary in age (Figure 2). A large area of southwest

Alberta prairie is underlain by formations of Tertiary age; the

Porcupine Hills and Willow Creek formations. Through Cardston and south to the International Boundary, the soft sandy shales and sands have influenced the soils where they occur near the present surface.

These strata are low in lime content. The most continuous section of these formations is in the Belly Buttes east of the Belly River -

Waterton River confluence and several hundred meters above the river

channel where erosion has exposed the colorful bedrock of the Willow

Creek formation.

The St. Mary River non-marine strata underlie the Willow Creek

formation of early Tertiary age and represent the uppermost Cretaceous strata in southwest Alberta. This formation consists mainly of highly

calcareous light gray sandstones and sandy shales. Irregular bedding

and cross-bedding are common. Soils influenced by these beds have a pronounced lime content. Freshwater oyster shells and coal beds are

common in this formation. Much of the prairie section of the three

study streams cuts through the St. Mary River formation.

The marine Bearpaw formation consists mainly of dark gray clay 10

Tertiary Porcupine Hills Non-marine, soft gray, clayey sandstones and clays. Willow Creek Non-marine, soft sandstones, shales and clays, commonly red, mauve and gray in color. Upper Cretaceous St. Mary River Non-marine highly calcareous sandstones, irregular bedded and cross-bedded sandy shales, and some coal near the base with oyster beds. Bearpaw Mainly marine dark gray, cl~y- shale and sandy shale with limestone concretions. Belly River Mainly non-marine, light gray, greenish gray and buff sandstones, interbedded with dark gray shales and some conglomerate lenses. Coal and oyster beds occur in the upper strata. Lower Upper Alberta Shale Marine, dark gray shale with Cretaceous (chiefly Benton) several bentonite beds; interbedded sandstone in lower 18 m. Lower Cretaceous Crowsnest Volcanics Volcanic tuffs and breccias. Blairmore-Kootenay Non-marine green, gray and reddish shale and sandstone, with thin conglomerate beds and coal seams. Jurassic Fernie Marine dark gray to black shales, with some phosphatic beds. Triassic Mainly marine, dark gray, sandy shale. Erosion Unconformity Palaeozoic Mainly marine limestones, dark calcareous shales and some quartzitic sandstones and conglomerates. Precambrian Marine slate, quartzitic sandstones varied in color.

Figure 2. Subsurface geological strata in southwest Alberta. 11 shales and sandy shales. A large area of Bearpaw extends from

Township 1 Range 21 northward to Township 8 Ranges 22 and 23. Much of the lower half of St. Mary River, where there is no riverbottom forest, flows through this formation. A narrow band of Bearpaw shale extends from Cardston south beyond Kimball, and from Kimball upstream on St.

Mary River to the mouth of Coalmine Coulee.

The Belly River strata are of freshwater origin and consist chiefly of gray, greenish and buff sandstones interstratified with gray, greenish and carbonaceous shales. The Belly River strata are not incised by the three streams, but are found in the bottom of the

Oldman River valley (once known as Belly River) at Lethbridge. There are several coal beds in Belly River strata and coal has been mined at and near Lethbridge.

Much of southwest Alberta is veneered with glacial deposits left when the glaciers melted (Wyatt, 1939). Glaciation was general over most of the area. There is also widespread distribution _of reworked glacial deposits as well as alluvial and lacustrine deposits transported by rivers and creeks. The unconsolidated surface deposits in southwest Alberta are classified into four major types:

1. Residual and sorted residual deposits

2. Glacial deposits - moraine, till, boulder clay

3. Re-sorted glacial deposits

4. Transported deposits of alluvial, lacustrine and dune or eolian origin.

There are very few areas of residual soil here and those are principally marginal to the Belly Buttes. The morainal material transported from the mountains consists largely of limestone, shale, 12

slate and quartzitic sandstone, or volcanic rock. The detrital

material transported from the northeast by the Keewatin glaciers

consists largely of igneous rocks such as granite, gabbro, gneiss,

and greenstone, and locally of harder sandstone from the younger rock

formations from beneath the plains over which the ice moved.

There is evidence of an overlapping of the Keewatin boulder

clays and corresponding material frora the mountain glaciers. It would appear that the mountain glaciers extended at least as far east

as Range 21 and that later the Keewatin glaciers extended considerably

farther west and over-rode the older mountain boulder clay and

moraines. Retreat of the glaciers is presumed to have occurred for

the last time about 9,000 years ago (Dyson, 1949).

Re-sorted glacial deposits are widely distributed especially

on the upland of the Blood Indian Reservation between St. Mary and

Belly Rivers. There is very little evidence of wind-sorting of the

silts and finer textured soils.

Along the courses of the larger valleys there are several well-defined flat-topped terraces, covered with well or poorly sorted

gravels, sands and clays. There is a conspicuous bed of washed gravel

interbedded with glacial till, the Saskatchewan gravels, that are

interglacial in age.

The fourth type of surface material, the transported deposits,

are represented along southwest Alberta stream courses where the

principal transporting agent is water.

Soils on the prairie section of southwest Alberta are

generally fertile. Aspen parkland and some adjacent fescue prairie are

in the black soil zone and east of this are the shallow black soils 13 which grade gradually into dark brown soils of the mixed grass prairie

and shortgrass plains. The dark brown and most of the shallow black

zones underlie treeless prairie. The soils along the river and creek

bottoms are of alluvial deposition and some, still liable to frequent flooding, are quite variable in texture and utilization (Wyatt, 1939).

Undoubtedly the Lewis Range of the Rocky Mountains on the west

side of the area is the most prominent topographic feature of the

landscape. In this part of Alberta the break from mountains to plains

is fairly rapid, there being no wide range of foothills. These few

foothills are characterized by a series of rock outcrops running parallel to the mountain front. The Porcupine Hills, elevation 1,580 meters, is a prominent topographic feature bordering Oldman River on

the north. East of St. Mary River the land gradually rises to Milk

River Ridge, which has the appearance of a high north-south plateau

with a maximum elevation of 1,433 meters. Between these three land-

marks lies the area of study which is in the nature of a large plain

of level to gently rolling land ranging in elevation from 900 meters

to 1,200 meters. Of the approximate 7,700 square kilometers between

the Rocky Mountains, the summit of Milk River Ridge and the south

slopes of the Porcupine Hills, almost two-thirds is drained by the

St. Mary-Lee-Belly stream system.

South and east of Milk River Ridge the waters flow into Milk

River and thence into the Missouri system and ultimately into the

Gulf of Mexico. West of the Rocky Mountain Continental Divide the

waters flow into the Flathead drainage and by way of the Columbia

River into the Pacific Ocean.

With the exception of the Waterton Lakes in Waterton Lakes 14 National Park, Alberta there are no large natural lakes on southwest

Alberta's prairie. CLIMATE

Bounded on the west by the mountains and foothills of the

Rocky Mountains, the whole of the three prairie provinces, Alberta,

Saskatchewan and Manitoba, consists of vast plains deeply cut by river valleys and gently sloping toward the east and northeast. The western mountains form a fairly effective barrier to the maritime influence of the Pacific and at the same time the area is left exposed to the inflow of cold Arctic air masses from the north (Canada, 1969).

Summers are normally warm but winters are usually long and intensely cold. Throughout southwest Alberta mean temperatures are below O degrees Centigrade from November through March (Table 3).

Winter cold across the province increases from southwest to northeast.

Winter temperatures on the prairies may vary widely from month to month during a single winter, or from year to year depending on the character and path of air masses passing over the region. In some winters, with a steady flow of cold polar air, a cold spell may last for several weeks. On the other hand, in some winters the southerly flow of Arctic air may be quite weak and air of Pacific origin moves eastward at the surface bringing mild weather. There have been winter months when a substantial portion of the western prairies have been 14 degrees Centigrade or more below normal and there have been winter months when the temperature has averaged 14 degrees Centigrade warmer than normal over a large section of Alberta.

Winter temperatures in the lee of the Rockies reflect the 16

Table 3. Mean daily temperature in degrees Centigrade and degrees Fahrenheit at Cardston, Alberta.

Month Cent. Fahren.

January -7.4 18.7 February -6.5 20.3 March -2.5 27.5 April 4.5 40.2 May 10.3 50.6 June 13.7 56.5 July 17.9 64.1 August 16.1 61.1 September 11.6 52.7 October 6.6 43.8 November -0.4 31.3 December -4.2 24.4

Year 5.0 40.9

warming effect of the "chinook" wind which occurs from the North West

Territories to the United States but is most pronounced in southern

Alberta with effects noticeable as far east as Regina, Saskatchewan.

Characteristically, the chinook occurs as a westerly or southwesterly wind and is brought about by the subsidence east of the western mountain ranges of maritime Polar air from the Pacific. This air is

cooled adiabatically at the saturated lapse-rate in its ascent over

the mountains but in its descent to the plains it is warmed again

adiabatically at the dry lapse-rate which is twice the cooling rate

during the ascent. Consequently this air reaches the foohills at a much higher temperature than it had at a corresponding level on the

. western slopes. The chinook is most striking when it occurs following 17 a cold wave that has been accompanied by snow. The sky clears abruptly and temperatures may rise as much as 34 degrees Centigrade in

24 hours. The bright sunshine and above freezing temperatures cause the snow to melt rapidly and some plants may be stimulated to begin growth prematurely with subsequent deleterious effects.

Temperatures rise rapidly from winter to summer and decline with equal rapidity from summer to wi~ter. The transition periods are usually confined to April and October. Monthly mean temperatures in southwest Alberta are above ten degrees Centigrade for the five months

May to September. Extreme maximum temperatures ·have exceeded 38 degrees Centigrade over most of the prairies. The highest recorded temperature for all Canada occurred at Gleichen, in southern Alberta, on July 28, 1903 when 46 degrees Centigrade (115 degrees F) was recorded. On the other hand, temperatures may fall to zero degrees

Centigrade or lower in every month of the year in less favored locations in the southern prairies.

The average frost-free period in southern Alberta ranges from

80 to 120 days, which is critically close to the minimum required for cultivated grain crops to reach maturity. The growing season to which the native plants have adapted is 85 days at Mountain View, 100 days at

Cardston, 110 days at Lethbridge and 120 days at Medicine Hat, the progressive lengthening occurring with increasing distance from the mountains and with decreasing altitude (Longley, 1968).

The prairie provinces are fortunate in receiving a high average of sunshine for the latitude; the annual total ranges from

2,000 to 2,350 hours in the prairies. July is the sunniest month with total exceeding 300 hours at most stations in south Alberta. 18

December is the dullest month of the year with all stations showing total less than 100 hours. There is a noticeable tendency for the sky to be either cloudless or completely overcast on the prairie (Canada,

1969).

Lying in the center of the continent and shielded from the

Pacific by the western mountain ranges, the Canadian prairies lack available sources for abundant precipitation. The region is favoured, however, by the fact that cyclonic activity is fairly vigorous and the hot summers are conducive to convection. The heaviest precipitation results from the lifting of extensive masses of moist air moving northward from the Gulf of Mexico and adjoining regions. Droughts are usually associated with abnormally low pressure in the North West

Territories which produces only a weak southward flow of cold air.

In marked contrast to the Pacific Coast with its winter maximum, the prairies have a rainy season from late May to early

October, although no season is without some precipitation. The light precipitation is somewhat mitigated by the fact that 60 to 75 per cent of the year's precipitation falls during the growing season when it can be utilized by plants.

During the summer the intense heating and resulting convection are conducive to thunderstorm activity. Unfortunately for agricultur- alists, hail frequently accompanies severe thunderstorms and may cause local or even widespread damage. Hailstorms, like thunderstorms, are more likely to occur over the open grassland than in forested areas.

Precipitation shows wide variations from year to year, with differences between the extreme annual amounts exceeding the mean annual total in most cases. Monthly precipitation totals are more 19 often in deficit than in excess. A month may have no precipitation over a large section of the western prairies, while occasionally monthly totals may exceed 25 centimeters. June and July are most likely to have high rainfall totals.

Floods are not ordinarily a serious problem on the prairies but high water in river systems with headwaters in the Rocky

Mountains may occur during the early summer when the flow is increased by melting snow and ice from the mountains. Local flooding may result from excessive local rains in smaller drainage basins during the summer season.

Winter snowfall is comparatively light with amounts ranging from 76 to 127 centimeters over the central prairies. This amount increases to 180 centimeters in the foothills of the Rockies and at least twice that amount in the highest ranges. Snow may fall in any month except July and August, although measurable snow is unusual in

June. The first snow cover usually appears in late October and snow disappears in early April. A combination of heavy snowfall and wind causes drift buildup in coulees and along the streams throughout winter. LITERATUREREVIEW

The riverbottom forest community in southwest Alberta is found on stream floodplains which show characteristics of Melton's classification. Melton (1936) proposed one category containing floodplains seldom or 11eyer subject to over-bank floods. These lack sedimentary deposits on the surface and lateral corrosion results in the formation of meander loops. A second category included floodplains frequently subject to over-bank floods with considerable sedimentary deposits on the surface.

In a study of the Coeur d'Alene River floodplain in Idaho,

Humphrey (1924) came to the conclusion that the vegetation on the floodplain of that river had spread from the south and east into Idaho because of the constancy of the moisture factor along the river floodplain. Actual disseminule transfer probably came about through winds and the movements of birds.

Lee (1945) reported 40 species of tall trees, 9 species of small trees and 14 species of shrubs from the floodplain forest of the

White River in Indiana. Dominant tree species were Acer negundo, Acer saccharinum, Celtis occidentalis, Fraxinus americana, Platanus occidentalis, Populus deltoides, Salix nigra, Ulmus americana, Ulmus thomasi. A well developed small tree-shrub layer was lacking in the stratigraphic development of the forest and stands along the river showed striking similarity even though the river passed through four botanical areas of striking difference in the upland forest. Micro- 21 climate was thought to be of more importance than macroclimate.

Ware and Penfound (1949) studied the floodplain of the South

Canadian River in Oklahoma and found sparse vegetation due to annual destruction by floods, shifting of sand, a high rate of evaporation, the intense heat of the sand surface, and the drying out of sand. A total of 85 species of plants was found. Dominant tree species were

Populus deltoides, Salix interior and Tamarix gallica.

The Mississippi River floodplain in northwestern Tennessee has been given special study by Shelford (1954). The two dominant large tree species were Populus deltoides and Salix nigra. The climate of the area was favorable for _the rapid growth of trees on the higher terraces of the floodplain. Annual rainfall was 112 to 125 centimeters and the mean annual temperature was 16 degrees Centigrade. Nearly

~very year, two or more early stages of the floodplain forest were inundated, the length of submergence varying from a week to two and one-half months. Usually flooding came early in the spring but sometimes as late as May or June. The cottonwood area near Tiptonville Ferry received a layer of fine silt each year, probably amounting to several inches. In the mature cottonwood - willow forest the trees were more than 45 centimeters in diameter and 60 per cent were cottonwoods and 40 per cent willow. The principal shrub was American elder

(Sambucus canadensis) with occasional rough-leaved dogwood (Cornus drummondii). The herb layer was usually poorly developed. Cotton- woods of 50 to 60 centimeters diameter at breast height showed 20 annual growth rings in the Donaldson area north of Tiptonville. In the Reelfoot Lake area cottonwoods grew in diameter at the rate of 2.1 centimeters or more per year, but in Iowa, farther north, growth was 22 measured at only 1.0 centimeter per year. The cottonwood stand near the Tiptonville Ferry was estimated about 40 years old, counting from the time the cottonwoods were seedlings. The area was a sandbar island in the river 52 years earlier. Estimated time for the complete development of the climax Tulip-Oak Forest was 600 years.

In a survey of the vegetation of Alberta, Moss (1955) described the flats of rivers in the prairie parkland of southwest

Alberta as being commonly dominated by poplars and willows with associated birch, alder and a variable assemblage of herbaceous species. The leading poplar species designated were Populus angustifolia, P. acuminata, R_. sargentii, P. trichocarpa (near the mountains) and P. balsamifera. There was evidence of hybridization between certain of the cottonwoods and also between the two balsam poplars. The chief willow species indicated were Salix lutea, .§.. caudata, S. interior var. pedicellata, ~• melanopsis and§_.~- daloides. Wistendahl (1958) described the floodplain of the Raritan

River, New Jersey as flowing through three of four geologic provinces with floods unpredictable from zero to sixteen days per year, March having the most floods. High precipitation occurred in the summer when floods were scarce. Succession trends on new alluvium reflected the dynamics of stream action. The dominant tree species on the levee were willow, river birch, sycamore and box elder.

Hosner (1958) found that cottonwood (Populus deltoides) seedlings could survive only with less than eight days complete inundation by flood water with variable rates of recovery.

Weaver (1960) reported that the pioneer tree species on the 23

floodplain of the Central Missouri Valley were Salix amygdaloides, !· nigra and Populus sargentii. The floodplains were subject to occasional or frequent flooding but were moderately to well drained between overflows. He concluded that it was not the soil type alone

that determined the kind and amount of native vegetation but rather aeration and constancy of water supply of these mostly productive soils that directly affected their v~~etation.

Lindsay~ al (1961) reported 629 species of plants from a

study of the vegetation and environment along the Wabash and

Tippecanoe Rivers in Indiana. Pioneer tree species were cottonwoods

(Populus spp.) and black willow (Salix nigra). A medium-sized island largely built by a major flood supported both cottonwoods and willows up to 33 centimeters diameter after 15 years. There were from four to

seven stages in succession from pioneer grass-forb to the floodplain edaphic climax.

Early taxonomic studies which included accounts of the plant species of the stream valleys include the work of Macoun (1883-1909) on plants of the western prairies, Standley (1921) on the flora of

Glacier National Park in }iontana, and Rydberg (1922, 1932) on the floras of the Rocky Mountains and plains and prairies of central North

America. An early edition of Native Trees of Canada (1956) gave good accounts of tree species taxonomy and distribution. In 1955 Moss presented an overview of the vegetation of Alberta which preceded his monumental work (1959) the Flora of Alberta, a most comprehensive work for the time and still the most useful taxonomic tool for the province.

Supplementary accounts of southwest Alberta plants are to be found in

Budd (1957), Booth (1950), and Booth and Wright (1959). 24

Some help in understanding the plants of the upper reaches of

Belly River and Lee Creek was provided by Breitung's (1957) enumer-

ation of the plants of Waterton Lakes National Park, Alberta.

Popular treatments including some of the riverbottom species are Cormack's (1967) Wild Flowers of Alberta and Kuijt's (1972) Common

Coulee Plants of Southern Alberta. A detailed and complete account of

the northern great plains flora was plovided by Boivin's (1967) Flora

of the Prairie Provinces.

Specific treatment of the woody vascular plants found along

southwest Alberta streams was done in Shaw's (1968) Guide~ the

Woody Plants of the Lee Creek Valley and (1972) Guide !.Q. the Woody

Plants of the Prairies, Foothills and Valleys of Southwest Alberta.

Brayshaw (1965) has provided the necessary treatment of native

poplars of southern Alberta and their hybrids, which is most valuable

in both taxonomic and ecologic evaluations of streamside communities. METHODSAND MATERIALS

The riverbottom forest community of St. Mary River, Lee Creek and Belly River was chosen for this ecologic and taxonomic study of

the vascular flora b~cause of a personal interest of long standing in

these streams and their vegetation. Discounting plant collecting and ecosystem observations spanning the decade 1959 to 1969, the actual planned research for this dissertation covered the years 1970 through

1973. Intensive field data collection was carried out during the growing seasons of 1970, 1971 and 1972 with follow-up and fill-in studies completed by autumn, 1973.

Study sites along the stream systems were chosen with two purposes in mind, intensive plant collection only, and both plant collection and ecosystem data collection. Within this frame of reference sites were evaluated from headwaters to outlet on each of the three streams during the summer of 1970. Some sites were dis- carded because they did not fall in the riverbottom forest community proper, being in upstream transition zones. Others were not selected because of community alteration by livestock overgrazing, timber cutting, farmstead site and cattle feedyards. Final sites meeting standards of reasonable expectation of similarity to pre-1870 climax community aspect numbered 19 (Figure 3). A major objective of the study was to describe the species of vascular plants and their ecologic relationships in the apparent edaphic-climatic climax of the present. 26

17 km

Glenwood Bridge

Belly River

8. Hillspring Park •

Woolford Park Town Cardwell's Island Dam • 2. East of Aetna 7. Hwy 5 Lee Creek • Bridge St. Mary River * Cook's Ranch -- ---

Figure 3. Study sites on St. Mary River, Lee Creek and Belly River in southwest Alberta. Major ecologic and taxonomic sites are numbered 1 - 10. Minor taxonomic sites are indicated*• 27

There were 10 numbered major ecologic-taxonomic sites. Four were chosen on St. Mary River. From upstream to downstream, with the assigned name and legal description, the sites were (1) Cook's Ranch,

SW¼;S9 Tl R25 W4; (2) East of Aetna, SE¼ S19 T2 R24 W4; (3) Cardwell's Island, NE¼ S30 T2 R24 W4; and (4) Woolford Park, NE¼ S31 T2 R24 W4.

On Lee Creek there were two major study sites and these, in upstream to downstream order were (5) Town Dam, NE¼ S26 T2 W4; and

(6) Slaughter Hole, Nl/~ S4 T3 R25 W4.

Belly River had four major study sites and from upstream to downstream they were (7) Highway 5 Bridge, SW¼;Sl7 T2 R28 W4; (8)

Hillspring Park, NE¼and NW1~Sl3 T3 R28 W4; (9) Glenwood Bridge, S~ S6 TS R26 W4; and (10) Standoff, S27 S28 S33 S34 T6 R25 W4 and S2 T7

R25 W4.

Nine minor taxonomic sites were chosen. On St. Mary River these were at Coalmine Coulee, SE¼ S22 Tl R25 W4; Kimball Park, S~ Sl

T2 R25 W4; East of Cardston, unsurveyed Blood Indian Reserve; Christ- ensen Farm, SW¼S27 TS R23 W4; and Blood Reserve Cut-off, SW~ S30 T6

R22 W4.

Minor sites on Lee Creek were The Dugway, S5 Tl R27 W4; The

Narrows, S20 T2 R26 W4; and Cardston, town of Cardston.

The one minor site on Belly River was at the Belly River -

Oldman River confluence, S27 S28 T9 R23 W4.

Since prior to this study no precise evaluation of the vascular flora of the riverbottom forest had ever been made, intensive plant collecting was done throughout the growing season, beginning in early May and ending in late Sep·tember. Important sites were collected thoroughly from five to seven times to insure complete records 28 of all species. Specimens were preserved according to standard herbarium practice. After careful checking and comparison with known material all specimens collected, some 1500 numbers, were deposited in the Herbarium of Brigham Young University, Provo, Utah (BRY). A duplicate set of specimens remains in the author's private herbarium at Cardston, Alberta.

Taxonomy of the poplars follows Brayshaw (1965), the genus

Cryptantha after Higgins (1971), the genera Astragalus and Oxytropis follow Welsh (1960), and the remainder are after Moss (1959), Boivin

(1967), Booth (1950), and Booth and Wright (1959).

A key was developed for use in identifying riverbottom forest plant species.

After several field trials, using various methods, a standard procedure for obtaining numerical data on forest stands evolved.

Information leading to density, dominance and frequency was desired throughout. Each forest stand was sampled by following a pre- determined pattern; travel parallel to the stream, sample at intervals, interrupt the interval whenever non-forest terrain was crossed. Field data were recorded on data sheets similar to those suggested by Cox (1967).

Data on trees, tree reproduction and clumped shrubs was best obtained by using the point-centered quarter method recommended by

Cottam and Curtis (1956). Point-to-plant distance determination by tape measure proved quite difficult because of the brush and so an optical range finder (Edscorp), also recommended by Cottam and Curtis

(1956), was substituted for the tape with the operator standing beside the plant and sighting back to a 2-meter rod painted alternately 29 red and green at decimeter intervals set at the point of quadrant intersection. The travel interval between points was 30 meters and three strata - trees, tree reproduction and clumped shrubs were sampled from the same point.

Dominance calculations were based on diameter-breast-high for trees, tree reproduction dominance on height, and canopy diameter for clumped shrubs. All measurements were based on estimates with frequent tape measure checks to insure reliability.

The line-intercept method, using a 30-meter steel tape placed at right angles to the line of travel at 30-meter intervals, proved to be satisfactory for obtaining information on clonal thicket shrubs.

Ten 30-meter lines were sampled per stand. Bare ground and litter intercepts were not recorded; these were left for inclusion in quadrat herbaceous plant sampling.

A 2 dm by 5 dm quadrat supported on legs and made from small welding rod was used for herbaceous plant sampling. Sides of the quadrat were painted alternating colors at 1 dm intervals for ease in estimating percentage cover. Fifty quadrats were sampled per stand at

10-step intervals. Bare ground and litter estimates were obtained for the entire stand by this method.

From all data, calculations of absolute and relative density, absolute and relative dominance, and absolute and relative frequency were made with a final summation of relative values to yield importance value.

Soil characteristics were evaluated in several ways on the ten sites chosen for intensive study. To determine soil physical characteristics 100 samples per stand were taken at 10-step intervals with 30

a steel rod penetrometer and penetration depth was recorded to the

nearest next decimeter. Physical characteristics of the gravel on

gravel bars occupied by pioneer forest stands were determined by

taking three to five samples with a shovel, screening each sample with

a sieve of 0.5 by 0.5 cm square hole design, and calculating percentage

rock and percentage sand; sand being all particles passing through the

sieve mesh. Comparative samples were also taken from sites occupieJ

by sandbar willow.

Five soil samples per site were collected in plastic bags at

(1) surface on pioneer community gravel bar, (2) surface in mature

forest, (3) 2 dm depth in mature forest, (4) surface on adjacent

fescue prairie grassland, and (5) 2 dm depth on fescue prairie grass-

land. All rocks greater than 0.5 cm in diameter were removed from the samples. These samples were analyzed in the soils laboratory of

the Brigham Young University Department of Botany and Range Science

for percentage sand, percentage silt, percentage clay, type, pH, and

parts per million soluble salts following the directions of Bouyoucos (1936).

To determine average age of trees in a stand as well as the

age of the oldest-appearing trees, samples were taken with a 46 cm

increment borer and the corings were stored in glass tubing until

rings could be counted in the laboratory. So many of. the trees cored

had heart rot (about 40%) that much of the coring was unproductive.

However, sufficient growth ring information was obtained to justify

the construction o_f aging formulae for tree species. These formulae

were based on the average number of annual rings per centimeter of

xylem and the tree trunk diameter at breast height. 31 Valley profiles were developed for each of the ten major study sites utilizing a hand-held level, 30-meter steel tape, optical range finder, and pacing estimates. From these profiles the fraction of the river valley occupied by riverbottom forest was derived, plus forest height above stream level, and terrace arrangement.

General observations and photographic work were carried out during all seasons of the years 1970 through 1973. Important pheno- logical dates were recorded to yield seasonal development trends. The effects of stream flooding were noted with special attention to poplar seedling submergence and survival, channel alteration, silt deposition, mature forest destruction ~y erosion, and gravel bar formation.

Historical data on river changes and forest evolution and use were obtained through correspondence and interviews as well as library sources. General observations on bird and mammal life were also made throughout the study years. RESULTS

General Features of River Valleys and Riverbottom Forest

Typical riverbottom forest begins on St. Mary River 3.2 km south of the International Boundary where the river abruptly leaves the aspen parkland-fescue prairie transition and winds through the fescue prairie portion of the grassland biome. Riverbottom forest is continuous along 48 river kilometers to St. Mary Reservoir except for one short discontinuity at the mouth of Coalmine Coulee. Below St.

Mary Reservoir riverbottom forest is lacking for the 80 river kilometers to the river's confluence at Lethbridge. The lack of riverbottom forest on St. Mary River coincides with river channel restraints imposed by the Bearpaw Shale formation (Figure 4).

Streamfall along the river length averages 3.4 meters per kilometer.

Where glacial and/or alluvial gravel deposits occur, riverbottom forest has developed (Figure 5).

On Lee Creek, riverbottom forest begins 1.6 km above the hamlet of Beazer. It is continuous for 20 stream kilometers to the mouth of Lee Creek below Cardston. Riverbottom forest·development is coincident with gravel bar formation. Streamfall averages 0.75 meters per kilometer.

Riverbottom forest development begins on Belly River 1.6 km above Highway 5 bridge. As with St. Mary River and Lee Creek, the

transition forest changes abruptly to riverbottom forest which is 33

Figure 4. St. Mary River 3 km dowstream from the St. Mary Dam. Riverbottom forest has not developed on this part of the river where there are no gravel bars and restraints are imposed on the river channel by the exposed horizontal strata of the Bearpaw Shale formation.

Figure 5. Site 4 - Woolford Park, a typical riverbottom forest stand on the second terrace of St. Mary River. Willow Creek bedrock is exposed on the river's far bank and the road in the foreground crosses the fourth terrace. 34

continuous to the.Belly River - Waterton River confluence at Standoff.

Riverbottom forest development coincides with gravel bar formation

for the 48 stream kilometers. Streamfall averages 3.2 meters per kilometer. The channel pattern of the three streams is similar. They are

''meandering" streams in the definition of Neill and Galay (1967). The potential energy of moving water ha$ given these streams the ability

to carve channels to their present shape. The flow pattern obeys the

laws of stream morphology described by Yang (1971). Riverbottom

forest is found on streams that have not reached a final static equil-

ibrium, but are still in a state of dynamic equilibrium, constantly adjusting to achieve an approximate balance between work done and load imposed. Streamflow is such that degradation and aggradation occur each year. The peak periods of channel alteration and gravel bar

formation were found to coincide with peak streamflow in late May and early June. The inability of these streams to adjust widths in accordance with velocity has led to the alternate deposition of gravel bars, first on one side of the stream and then on the other wherever the water has had access to transportable gravels. Gravel deposits alternating with degraded banks are characteristic of the meander pattern.

Pioneer stands of riverbottom forest were observed growing on gravel bar formations, but never on sand bars. On nine such pioneer riverbottom forest sites the gravel, on which many small poplars 0.15

to 0.6 meters tall were growing, consisted of 61.1% rocks greater than

0.5 centimeters in diameter and 38.9% of particles less than 0.5 cent-

imeters in diameter, in other words, sand. On sites occupied by small 3S sandbar willows, 100% of each soil sample passed through the 0.5 centimeter mesh screen (Table 4).

Table 4. Results of the mechanical analysis of soils sampled at 9 sites occupied in part by a pioneer riverbottom forest connnunity and in part by a sandbar willow connnunity. Each value is the average of 10 samples from the upper 2 dm at each location. Sand was any particle capable of passing through a 0.5 cm by 0.5 cm square mesh screen.

Pioneer riverbottom forest Sandbar willo:-1 Site % rock % sand % rock % sand

1. Cook's Ranch 56.1 43.9 0.0 100~0 2. East of Aetna 57.1 42.9 o.o 100.0 3. Cardwell's Island 64.2 35.8 o.o 100.0 4. Woolford Park 66.7 33.3 o.o 100.0 5. Town Dam 70.3 29.7 o.o 100.0 6. Slaughter Hole 42.1 57.9 o.o 100.0 7. Highway 5 Bridge 78.2 21.8 o.o 100.0 8. Hillspring Park 69.9 30.1 o.o 100.0 9. Glenwood Bridge 45.7 54.3 0.0 100.0

Average 61.1 38.9 o.o 100.0

Depth of easy penetration by the penetrometer on gravel bars occupied by pioneer riverbottom forest ranged from 0.0 dm to 1.0 dm, the mean being 0.4 dm. Ten gravel bars were sampled, one at each major site, with 100 penetrometer readings per site.

Gravel bars formed by annual flooding were available to forest invasion and development by late June. Successful invaders were able to cope with a few days of submergence during flooding each spring.

In 1971, 1972 and 1973 average number of flood-days per year was four.

These occurred with greatest frequency during late May and early June. 36

The poplar species on pioneer riverbottom forest sites are well leafed out by the time annual flooding commences. Three pioneer riverbottom

forest. stands on gravel bars bet.ween Si.te 3 - Cardwell's Island and

Site 4 - Woolford Park on St. Mary River were observed for flood damage effect on the poplar species in lat.e spring of 1972. On each of the

three sit.es poplar seedlings 0.15 m t.o 0.6 m tall were numerous. There were also many herbaceous planes (Figure 6). All sites were subjected to over-sit.e flooding for three days. After flood water subsidence the pioneer tree stands were intact on two of the three gravel. bars. Seedl.i.ngs were somewhat muddy and bent over; otherwise

they appeared. to be uninjured. One week later they were thriving. A

shal.l.ow I.ayer of silt and sand 0.6 cm to 1.2 cm in depth had been deposited over the original gravel. by the flood water.

On the remaining gravel bar, largest of the three, not a trace of the former pioneer tree stand could be found. The flood water had been directed over this gravel bar, altering its shape completely.

All. plant life had been buried or washed away leaving several hundred square meters of fresh new gravel bar ready for re-invasion and establishment of the riverbottom forest community (Figure 7).

Lee Creek and the St. Mary and Belly Rivers are principally degrading streams with several different terrace levels (Figures 8,

9 and 10). Riverbottom forest is confined to the narrow band of gravel of the first and second terraces. The first terrace or "first bottom" of Lindsay et al (1961) is unstable from modern rive·r cutting and deposition and endures partial or total annual flooding. It supports the pioneer stages of riverbottom forest. The second terrace or "second bottom" is inundated only by floods of unusual proportions, 37

Figure 6. A pioneer riverbottom forest stand intact and thriving on the gravel bar in the foreground before 3 days of over-site flooding in June, 1972.

Figure 7. The same gravel bar as shown in Figure 6, after 3 days of over-site flooding in June, 1972. All living plants were removed by the flood; a small amount of non-living organic debris remained. 37 PLATE II

I ) (

Fig. a.--A«ropyron spicatu grown in the control nutrient level at the left and the one-sixth nitrogen level on the right.

Fig. b.--Agropyron spicatum grown in the control nutrient level on the left and the one-sixth phosphorus level on the right. 38

Figure 8. Site 1 - Cook's Ranch on St. Mary River. Riverbottom forest to the left is on a second terrace, the photographer was standing on fescue grassland on terrace three, and the truck is on terrace four. August, 1972.

Figure 9. Site 5 - Town Dam on Lee Creek. A first terrace pioneer riverbottom forest stand is left of the creek and a second terrace mature riverbottom forest stand is to the right. August, 1972. 38 PLATE III

- I'

Fig. a.--Sporobolus cryptandrus grown in the control nutrient level on the .ri�ht and the one-sixth nitrogen level on the left.

Fig. b.--Sporobolus cryptandrus grown in the control nutrient level on the right and the one-sixth phosphorus level on the left. 39 PLATE IV

Fig. a.--Aristida lon iseta grown in the control nutrient levef on the right and the one-sixth nitrogen level on the left.

Fig. b.--Aristida longiseta grown in the dontrol nutrient level on the right and in the one-sixth phosphorus level on the left. 39

,,,.------...... --- -... -. :--:.-~\>;;,..•: :: .--~- ...:·.-:· L ::-~_- .. :·. :-::·. : ••• • •I .·.·:. .·, • •. -·- :.::.·.:.:.:.:•:--•-·.-··-~:~~:t.- grassland terraces .·~-~--,' 1 ...... \ ....river ,.. second terrace Site 1 - Cook's Ranch St. Mary River .,_ 450

,. ·": : ,_,...... ---- . ,...... -,.: . • -· - f t - ---\ \_.---::.-:.•"'•.' . • • • •· . ores canopy , - \,• .. ·.--·-- • I • ,. • • ••: • •-=-~~------I grassland -... .. ~.:... - :· . . . :. . . - 6 - Slaughter Hole terrace Lee Creek +- 450 meters _.,

..... I -----forest-- -- canopy- --- - ... --' I -

Site 10 - Standoff Belly River ..,_330 meters---

Figure 10. Valley profiles for three stands of mature riverbottom forest in southwest Alberta. The vertical scale is exaggerated. 40 PLATE V

Fig. a.-s_p oro o us cry2tandrus control on the right and 1 I 21 nitrogen on left showing root development under low nitrogen level.

Fig. b.--Sporobolus crytandrus control on the right and 1/36 potassium level on the left showing short root development in low potassium. 40 such as the one of 1964. This second terrace supports the climax

riverbottom forest community.

Elevation increase from terrace to terrace was measured. From

low water level in the stream to mean level of the first terrace is 0.3 to 1.0 meters. The second terrace is 0.9 to 1.5 meters higher

than the first, and the third and fourth terraces are 1.2 to 2.4 meters higher than the second and thiLd terraces. The third and sub-

sequent terraces are occupied by the same fescue prairie grassland

counnunity that is climax on the surrounding rolling hills of southwest

Alberta.

At the ten study sites, mature riverbottom forest occupied 17%

to 50% of the rim-to-rim valley width. The average riverbottom forest occupancy of the rim-to-rim valley width was 32% (Table 5).

Table 5. Percentage of the valley cross-section occupied by mature riverbottom forest at the ten study sites in southwest Alberta.

Valley width Riv. Bot. Percentage Site rim-to-rim For. Riv. Bot. For.

1. Cook's Ranch 460 m 161 m 35% 2. East of Aetna 915 m 156 m 17% 3. Cardwell's Island 640 m 256 m 40% 4. Woolford Park 824 m 280 m 34% 5. Town Dam 610 m 153 m 25% 6. Slaughter Hole 564 m 153 m 27% 7. Highway 5 Bridge 305 m 153 m 50% 8. Hillspring Park 460 m 92 m 20% 9. Glenwood Bridge 244 m 117 m 48% 10. Standoff 460 m HBm ~%

Average 548 m 172 m 32% 41 PLATE V

Fig. a.--Aristida longiseta showing good growth in the one-sbch nitrogen level on the left and the control plant on the right.

Fig. b.-Aristida longiseta showing good growth in the one-sixth phosphorus level on the left and the control plant on the right. 41

No evidence was found of invasion of grassland terraces by tree species. Evidence was found in several locations of the invasion of the forest by grassland species, the invasion being accelerated by localized high intensity sheep grazing. Reproduction of tree species at high intensity grazing sites was nil (Figures 11 and 12).

Long unused river channels higher in elevation than the present river caannel were devoid of forest development.

The longevity of riverbottom forest stands was investigated and found to be dependent on factors other than possible age attainment and reproduction of its species. Few forest stands were found where tree species had grown to maturity, died, were dying, or were being replaced by forest or grassland. Most stands showed evidence of destruction during some stage of development by the eroding action of water on the forest-supporting gravel bar. Trees and shrubs washed away during the course of lateral degradation were deposited on newer gravel bars or were lodged against other plants farther downstream. Some had been lodged for several years, were partly decayed and had trapped sand, gravel and river debris (Figure 13).

The abrasiveness of transported gravels was found to have been most effective in de-barking woody stems and roots of transported plants and thus limiting their regeneration. Woody plant fragments were checked on gravel bars of each of the three study streams for regenerative growth following uprooting and transport by the water (Figure 13). No accurate count was kept, but the majority did not regenerate even following partial burial in gravel by flooding. All showed abrasion damage to the bark, smaller branches and roots, this damage being a direct function of streamflow velocity. 42

Figure 11. A climax riverbottom forest stand on St. Mary River. Shrubs and tree reproduction have been eliminated by brush clearing and sheep grazing over the 25-year period 1948 - 1973. November, 1973.

Figure 12. Kearl Ranch picnic grounds on Lee Creek showing the same non-reproductive nature of riverbottom forest exposed to long term (85 years) high intensity sheep and cattle grazing. Trees supporting the swing are Populus angustifolia 76 cm in diameter. 43

Figure 13. The Woodgrove Park area on St. Mary River showing abraded, lodged and unregenerating tree fragments. In the year 1898 the first terrace gravels supported a second terrace river bottom forest stand. A home once stood just beyond the driftwood pile in the foreground, a victim of lateral river erosion. 1973. 44

Under ideal conditions, doubling the water velocity may increase abrasive power by four times (Flint~ al, 1941). The Climax Forest

Major emphasis was placed on a study of the status of the climax riverbottom forest community occurring on St. Mary River, Lee

Creek and Belly River in southwest Alberta, Canada. In support of this, 10 climax riverbottom forest stands were studied in depth during the years 1970 to 1973. Stands 1 through 4 were located along

St. Mary River, stands 5 and 6 were on Lee Creek, and stands 7 through 10 were on Belly River. Numerical analyses, using standard methods, were done for the mature tree canopy, tree reproduction, clumped shrub understory, thicket shrub understory, and herbaceous understory. Each stratum of each stand was analyzed to provide relative density, relative dominance, relative frequency and their summation, importance value.

Following the example of Rice (1965), dominants in strata categories with very few species were designated as those species having importance values of 75 or more, based on the maximum importance value possibility of 300. Average number of species per stand for the tree canopy stratum was three, for tree reproduction three, and for clumped shrubs three. Therefore an importance value of not less than 75 designated stand dominants in these three strata.

Designation of dominants for remaining strata followed the reasoning that with more (or fewer) species, the importance values expected of dominants would lower (or raise) proportionately.

Average number of species per stand for the thicket shrub stratum 46 was 7.5. Applying the inverse proportion rule, a stand dominant would be so designated if it had an importance value of at least 30.

There was an average of 30 species per stand for the herbaceous plant stratum. The inverse proportion rule designates 7.5 as the least importance value for stand dominants.

Identification of plant species was based on collections made during the course of field work. One growing season, in 1971, was largely devoted to learning the field identification characters of herbaceous species not in flower at the time of data sampling. Tree species identification is based on the treatment of Alberta poplar species and their hybrids by Brayshaw (1965). Recognized poplar species found in this study were narrow-leaf cottonwood (Populus angustifolia), balsam poplar (P. balsamifera), and the hybrids between these two, called herein "AB hybrid" (P. angustifolia X balsamifera, or for brevity, P. X balsamifera). P. trichocarpa,

~ong considered a species in its own right, has recently been designated by Brayshaw (1965) P. balsamifera subsp. trichocarpa.

Recognizing only one species of balsam poplar greatly simplified field work inasmuch as the fruiting capsules necessary for the identification of P. trichocarpa as a species were produced infrequently.

Summary data for the mature tree stratum are presented in

Table 6. Density is expressed as the number of trees per hectare and relative dominance was derived from stem basal area and density.

Tree reproduction data summaries for each of the 10 stands are presented in Table 7. Tree reproduction included tree species ' individuals with a stem diameter at 1.4 meters above ground of 5 cm or less. Relative dominance was derived from average sapling height 47

Table 6. Mature tree stratum data from 10 riverbottom forest stands in southwest Alberta. Stand dominants have an importance value of 75 or more.

Stand Trees/ Rel. Rel. Rel. Imp. Species beet. Dens. Dom. Freq. Val.

1. Cook's Ranch PoEulus angustifolia 59.3 48.4 47.3 45.2 140.9 P. balsamifera 47.8 39.0 39.5 35.5 114.0 P. X balsamifera 15.5 12.6 13.2 19.3 45.1 Total 122.6 100.0 100.0 100.0 300.0

2. East of Aetna P. angustifolia 106.5 22.9 14.8 34.6 72.3 P. balsamifera 194.0 41. 7 34.2 34.6 110.5 P. X balsamifera 164.8 35.4 51.0 30.8 117.2 Total 465.3 100.0 100.0 100.0 300.0

3. Cardwell's Island P. angustifolia 34.5 22.9 31.2 30.8 84.9 P. balsamifera 40.8 27.1 16.0 30.8 73.9 P. X balsamifera 59.5 39.6 50.9 30.8 121.3 P. tremuloides 15. 8 10.4 1.9 7.6 19.9 Total 150.6 100.0 100.0 100.0 300.0

4. Woolford Park P. angustifolia 85.3 37.5 41.5 36.8 115.8 P. balsamifera 34.0 15.0 2.7 21.1 38.8 P. X balsamifera 107.8 47.5 55.8 42.1 145.4 Total 227.1 100.0 100.0 100.0 300.0

5. Town Dam P. angustifolia 130.5 35.0 26.5 35.0 96.5 P. balsamifera 130.5 35.0 24.7 30.0 89.7 P. X balsamifera 111.8 30.0 48.8 35.0 113.8 Total 372.8 100.0 100.0 100.0 300.0

6. Slaughter Hole P. angustifolia 86.0 32.5 17.8 34.8 85.1 P. balsamifera 52.8 20.0 21.3 21.7 63.0 P. X balsamifera 125.5 47.5 60.9 43.5 151.9 Total 264.3 100.0 100.0 100.0 300.0 48 Table 6 (continued)

Stand Trees/ Rel. Rel. Rel. Imp. Species beet. Dens. Dom. Freq. Val. 7. Highway 5 Bridge P. angustifolia 106.0 20.5 29.5 20.0 70.0 P. balsamifera 235.5 45.5 47.8 40.0 133.3 P. X balsamifera 117.5 22.7 15.5 30.0 68.2 P. tremuloides 47.0 9.0 3.5 5.0 17.S Picea glauca 11.8 2.3 3.7 5.0 11.0 Total 517.8 100.0 100.0 100.0 300.0

8. Hillspring Park P. anS!!stifolia 135.0 56.0 41.6 37.3 134.9 P. balsamifera 51.5 21.3 23.2 31.0 75.5 P. X balsamifera 54.8 22.7 35.2 31.7 89.6 Total 241.3 100.0 100.0 100.0 300.0

9. Glenwood Bridge P. angustifolia 13.3 5.0 0.9 5.3 11.2 P. balsamifera 153.5 57.S 61.4 52.6 171.5 P. X balsamifera 100.3 37.5 31.7 42.1 117.3 Total 267.1 100.0 100.0 100.0 300.0

10. Standoff P. angustifolia 98.S 52.S 43.5 47.4 143.4 P. balsamifera 9.5 5.0 6.5 10.5 22.0 P. X balsamifera 79.5 42.5 50.0 42.l 134.6 Total 187.5 100.0 100.0 100.0 300.0

Average all stands P. angustifolia 91.5 32.3 29.5 32.7 94.5 P. balsamifera 88.9 31.4 27.7 30.8 89.9 P. X balsamifera · 96.9 34.2 41.9 34.7 110.8 P. tremuloides 5.4 1.9 0.5 1.3 3.7 Picea glauca 0.6 0.2 0.4 0.5 1.1 Total 283.4 100.0 100.0 100.0 300.0 49

Table 7. Tree reproduction data from 10 stands of mature riverbottom forest in southwest Alberta. Stand dominants have an importance value of 75 or more.

Stand Sapl./ Rel. Rel. Rel. Imp. Species beet. Dens. Dom. Freq. Val. 1. Cook's Ranch PoEulus angustifolia 228.8 71.9 69.0 62.5 203.4 f.. balsamifera 59.5 18.7 20.6 25.0 64.3 P. X balsamifera 30.0 9.4 10.4 12.5 32.3 Total 318.3 100.0 100.0 100.0 300.0

2. East of Aetna P. angustifolia 219.3 66.7 54.5 47.8 169.0 P. balsamifera 75.3 22.9 35.6 30.4 88.9 P. X balsamifera 34.3 10.4 9.9 21.8 42.0 Total 328.9 100.0 100.0 100.0 300.0

3. Cardwell's Island P. angustifolia 126.5 43.8 31.5 34.8 110.1 P. balsamifera 60.3 20.8 31.8 21. 7 74.3 P. X balsamifera 54.3 18.8 13.5 30.4 62.7 P. tremuloides 48.3 16.6 23.2 13.1 53.0 Total 289.4 100.0 100.0 100.0 300.0

4. Woolford Park P. angustifolia 44.8 55.0 47.1 50.0 152.1 P. balsamifera 6.0 7.5 3.6 11.l 22.2 P. X balsamifera 30.5 37.5 49.3 38.9 125.7 Total 81.3 100.0 100.0 100.0 300.0

5. Town Dam P. angustifolia 11.3 12.5 9.8 23.8 46.1 P. balsamifera 60.3 67.5 65.7 47.6 180.8 P. X balsamifera 18.0 20.0 24.5 28.6 73.1 Total 89.6 100.0 100.0 100.0 300.0

6. Slaughter Hole P. angustifolia 42.3 35.0 28.5 38.1 101.6 P. balsamifera 24.3 20.0 20.5 23.8 64.5 P. X balsamifera 54.5 45.0 50.8 38.1 133.9 Total 121.1 100.0 100.0 100.0 300.0 so

Table 7 (continued)

Stand Sapl. / Rel. Rel. Rel. Imp. Species beet. Dens. Dom. Freq. Val.

1. Highway S Bridge P. angustifolia 83.3 25.0 26.6 26.2 77.8 P. balsamifera 158.0 47.5 49.9 43.5 140.9 P. X balsamifera 74.8 22.5 18.1 21.7 62.3 P. tremuloides 8.3 2.5 2.5 4.3 9.3 Picea glauca 8.3 2.5 2.9 4.3 9.7 Total 332.7 100.0 100.0 100.0 300.0

8. Hillspring Park P. angustifolia 198.5 35.0 39.4 30.4 104.8 P. balsamifera 142.0 25.0 21.6 21.7 68.3 P. X balsamif era 142.0 25.0 26.0 34.8 85.8 P. tremuloides 85.0 15.0 13.0 13.1 41.1 Total 567.5 100.0 100.0 100.0 300.0 9. Glenwood Bridge P. angustifolia 13.5 15.0 19.8 25.0 59.8 P. balsamifera 306.5 62.5 60.0 41.7 164.2 P. X balsamifera 110.5 22.5 20.2 33.3 76.0 Total 490.5 100.0 100.0 100.0 300.0 10. Standoff P. angustifolia 46.0 60.0 56.5 47.6 164.1 P. balsamifera 7.8 10.0 14.5 14.3 38.8 P. X balsamifera 23.0 30.0 29.0 38.1 97.1 Total 76.8 100.0 100.0 100.0 300.0

Average all stands P. angustifolia 113.3 42.0 38.3 38.6 118.9 P. balsamifera 81.5 30.2 32.4 28.1 90.7 P. X balsamifera 65.0 24.1 25.2 29.8 79.1 P. tremuloides 9.2 3.4 3.9 3.1 10.4 Picea glauca 0.8 0.3 0.2 0.4 0.9 Total 269.8 100.0 100.0 100.0 300.0 51 and density.

Clumped shrub data summaries for the 10 stands are presented in Table 8. Relative dominance for clumped shrubs was derived from average canopy coverage area and density.

Thicket shrub data summaries for the 10 stands are shown in

Table 9. Potentilla fruticosa exhibits some characteristics of clumped shrubs but because of its smallness and multiple stem habit it was included in thicket shrubs. The woody vines were also included.

Herbaceous stratum summaries for the 10 stands are presented in Table 10, and a summary of stand dominants in Table 11. Sub- shrubs were included with herbaceous species. Unoccupied space, that is bare ground, rock and litter, was estimated during herbaceous species sampling and data are presented separately in Table 12.

All calculations of community values were based on the equations of Cox (1967). ' 2w Using the formula C =a+ b , calculations of coefficient of community were made between all stands using all strata. Similarity values were totaled for all stands and dissimilarity values calcu- lated on the basis of a maximum similarity coefficient between two stands of 85 (Cox, 1967). Similarity and dissimilarity coefficients for the ten stands are shown in Figure 14, and stand similarity and dissimilarity totals in Table 13.

Comparison of coefficients of community and similarity and dissimilarity totals indicated that basic similarities within the ten stands outweighed the dissimilarities. These ten stands were therefore deemed to be parts of the same riverbot.tom forest 52

Table 8. Clumped shrub data from 10 mature riverbottom forest stands in southwest Alberta. Stand dominants have an importance value of 75 or more.

Stand Shrubs/ Rel. Rel. Rel. Imp. Species beet. Dens. Dom. Freq. Val. l. Cook's Ranch Betula occidentalis 33.5 50.0 86.0 38.5 174.5 Cornus stolonifera 28.0 41. 7 13.6 46.2 101.5 Salix lutea 5.5 8.3 0.4 15.3 24.0 Total 67.0 100.0 100.0 100.0 300.0 2. East of Aetna Betula occidentalis 223.0 100.0 100.0 100.0 300.0 Total 223.0 100.0 100.0 100.0 300.0

3. Cardwell's Island Betula occidentalis 20.0 93.8 98.6 85.7 278.1 Salix lutea 1.3 6.2 1.4 14.3 21.9 Total 21.3 100.0 100.0 100.0 300.0

4. Woolford Park Betula occidentalis 35.5 40.0 84.0 41.2 165.2 Cornus stolonifera 40.0 45.0 14.3 35.3 94.6 Salix bebbiana 6.8 7.5 0.7 11.8 20.0 Crataegus chrisocarEa 4.5 5.0 0.6 5.9 11.5 Salix lutea 2.3 2.5 0.4 5.8 8.7 Total 89.1 100.0 100.0 100.0 300.0 5. Town Dam Betula occidentalis 30.5 27.5 57.9 31.6 117.0 Salix lutea 36.0 32.5 26.1 31.6 90.2. Cornus stolonifera 33.3 30.0 14.9 31.6 76.5 Salix bebbiana 11.0 10.0 1.1 5.2 .16.3 Total 110.8 100.0 100.0 100.0 300.0

6. Slaughter Hole Betula occidentalis 7.4 37.5 68.6 29.2 135.3 Cornus stolonifera 6.4 32.5 17.9 33.3 83.7 Salix lutea 2.5 12.5 8.7 20.8 42.0 Crataegus chrisocarea 3.0 15.0 3.3 12.5 30.8 Salix bebbiana 0.5 2.5 1.5 4.2 8.2 Total 19.8 100.0 100.0 100.0 300.0 .S3

Table 8 (continued)

Stand Shrubs/ Rel. Rel.. Rel. Imp. Species beet. Dens. Dom. Freq. Val.

7. Highway 5 Bridge Betula occidentalis 59.0 57.5 57.4 47.4 162.3 Cornus stolonifera 33.3 32.5 39.7 36.8 109.0 Salix amxgdaloides 5.0 5.0 1.2 10.5 16.7 Salix bebbiaµa 5.3 5.0 1.7 5.3 12.0 Total 102.6 100.0 100.0 100.0 300.0

8. Hillsprir.g Park Betula occidentalis 13.5 70.0 81.0 50.0 201.0 Salix lutea 5.8 30.0 19.0 50.0 99.0 Total 19.3 100.0 100.0 100.0 300.0

9. Glenwood Bridge Betula occtdentalis ·282.3 32.5 78.7 31.3 142.5 Cornus stolonifera 477.8 55.0 10.7 50.0 115.7 Salix lutea 108.5 12.5 10.6 18. 7 41.8 Total 868.6 100.0 100.0 100.0 300.0

10. Standoff Cornus stolonifera 17.0 52.5 48.7 38.9 140.1 Salix lutea 11.3 35.0 43.2 38.9 117.1 Betula occidentalis 4.0 12.5 8.1 22.2 42.8 Total 32.3 100.0 100.0 100.0 300.0·

Average all stands Betula occidentalis 79.6 52.1 72.0 47.7 171.8 Cornus stolonifera 44.2 28.9 16.0 27.2 72.1 Salix lutea 21.4 14.0 11.0 19.5 44.5 Salix bebbiana 3.8 2.5 0.5 2.7 5.7 Crataegus chrxsocarEa 3.0 2.0 0.4 1.8 4.2 Salix amxgdaloides 0.8 0.5 0.1 1.1 1. 7 Total 152.8 100.0 100.0 100.0 300.0 54

Table 9. Thicket shrub data from 10 mature stands of riverbottom forest in southwest Alberta. Stand dominants have an importance value of 30 or more.

Stand Rel. % Rel. Rel. Imp. Species Dens. Cover Dom. Freq. Val.

1. Cook's Ranch Elaeagnus commutata 34.7 7.9 29.2 24.4 88.3 S~phoricarpos occidentalis 22.1 3.6 13.3 12.3 47.7 Rosa woodsii 18.3 3.3 12.2 14.6 45.l. Juniperus horizontalis 6.0 5.7 21.0 14.6 41.6 Arctostaphilos uva-ursi 7.2 4.2 15.5 12.2 34.9 Amelanchier alnifolia 6.0 1.6 5.9 7.3 19.2 Prunus virginiana 3.7 0.5 1.8 7.3 12.8 Potentilla fruticosa 2.0 0.3 1.1 7.3 10.4 Total 100.0 27.1 100.0 100.0 300.0

2. East of Aetna Elaeagnus commutata 61.6 53.8 62.0 41.0 164.5 Potentilla fruticosa 31.4 25.2 29.0 41.0 101.4 Juniperus horizontalis 4.3 0.7 7.6 4.5 16.4 Prunus virginiana 1.1 0.8 1.0 4.5 6.6 Rosa woodsii 1.1 0.3 0.3 4.5 5.9 Amelanchier alnifolia 0.5 0.1 0.1 4.5 5.1 Total 100.0 80.9 100.0 100.0 300.0

3. Cardwell's Island Elaeagnus commutata 23.9 4.6 23.4 18.8 66.1 Symphoricarpos occidentalis 46.4 6.6 33.6 18.8 98.8 Potentilla fruticosa 9.8 2.5 12.8 18.8 41.4 Am.elanchier alnifolia 9.4 1.7 8.8 16.7 34.9 Arctostaphilos uva-ursi 5.6 1.9 9.7 10.3 25.6 Rosa woodsii 4.5 0.6 2.9 14.6 22.0 Juniperus horizontalis 0.4 1.7 8.8 2.0 11.2 Total 100.0 19.6 100.0 100.0 300.0

4. Woolford Park Elaeagnus commutata 39.1 3.1 36.0 23.6 98.7 Amelanchier alnifolia 19.2 1.7 19.5 23.6 62.3 Rosa woodsii 13.5 0.8 8.8 14.7 37.0 Symphoricarpos occidentalis 10.3 0.6 7.0 11.8 29.1 Potentilla fruticosa 9.0 0.4 4.4 11.8 25.2 Arctostaphilos uva-ursi 5.1 0.9 10.7 5.9 21.7 Shepherdia argentea 1.3 0.5 5.5 2.9 9.7 Juniperus connnunis 1.9 0.4 4.3 2.9 9.1 Juniperus horizontalis 0.6 0.3 3.8 2.8 7.2 Total 100.0 8.7 100.0 100.0 300.0 55 Table 9 (continued)

Stand Rel. % Rel. Rel. Imp. Species Dens. Cover Dom. Freq. Val. 5. Town Dam Rosa woodsii 51.8 14.2 50.7 18.8 121.3 Amelanchier alnifolia 15.0 5.0 17.9 20.8 53.7 S~phoricarpos occidentalis 17.5 3.6 12.9 20.8 51.2 Prunus virginiana 10.7 3.2 11.4 20.8 42.9 Elaeagnus commutata 3.8 0.7 2.5 10.4 16.7 Juniperus horizontalis 0.6 0.7 2.5 4.2 7.3 Arctostaehylos uva-ursi 0.2 0.5 1.8 2.1 4.1 Rubus strigosus 0.4 G.l 0.3 2.1 2.8 Total 100.0 28.0 100.0 100.0 300.0

6. Slaughter Hole Symphoricarpos occidentalis 33.9 8.3 35.8 17.9 87.6 Rosa woodsii 25.8 5.2 22.5 15.4 63.7 Amelanchier alnifolia 16.0 4.1 17.7 20.6 54.7 Elaeagnus commutata 9.6 2.2 9.5 17.9 37.0 Prunus virginiana 4.7 0.7 3.4 12.8 20.9 Clematis ligusticifolia 5.2 0.8 3.6 5.1 13.9 Potentilla fruticosa 1.4 0.3 1.5 5.1 8.0 Sheoherdia argentea 1.7 0.7 3.2 2.6 7.5 Juniperus horizontalis 1.7 0.6 2.8 2.6 7.1 Total 100.0 22.9 100.0 100.0 300.0

7. Highway 5 Bridge Arctostaph:tlos uva-ursi 12.3 21.1 32.8 14.3 59.4 Rosa woodsii 27.7 5.5 8.6 17.9 54.2 Elaeagnus commutata 23.2 9.5 14.7 10.7 48.6 Juniperus horizontalis 5.2 13.9 21.6 14.3 41.1 S~phoricarpos occidentalis 18.1 3.9 · 6.0 14.3 38.4 Shepherdia canadensis 5.8 4.3 6.7 10.7 23.2 Amelanchier alnifolia 3.9 1.6 2.5 7.0 13.4 Salix interior 1.9 1.8 2.8 3.6 8.3 Juniperus communis 0.6 1.6 2.5 3.6 6.7 Potentilla fruticosa 1.3 1.2 1.8 3.6 6.7 Total 100.0 64.4 100.0 100.0 300.0

8. Hillspring Park Elaeagnus commutata 64.9 7.8 67.8 41. 7 174.4 S~phoricarpos occidentalis 26.0 3.2 27.8 33.3 87.1 Rosa woodsii 7.8 0.4 3.5 16.7 28.0 Amelanchier alnifolia 1.3 0.1 0.9 8.3 10.5 Total 100.0 11.5 100.0 100.0 300.0 56 Table 9 (continued)

Stand Rel. % Rel. Rel. Imp. Species Dens. Cover Dom. Freq. Val.

9. Glenwood Bridge woodsii 28.1 26.1 43.8 22.7 94.6 Elaeagnus commutata 28.7 13.2 22.1 22.7 73.5 S:zi::!phoricarpos occidentalis 29.2 12.8 21.5 22.7 73.4 A.melanchier alnifolia 11.8 6.8 11.4 18.2 41.4 Prunus virginiana 1.1 0.3 0.5 9.1 10.7 Salix interior 1.1 0.4 0.7 4.6 6.4 Total 100.0 59.6 100.0 100.0 30(;,Q

10. Standoff S~phorica!EoS occidentalis 57.8 6.6 49.5 32.3 139.6 Rosa woodsii 25.8 3.1 23.6 29.0 78.4 A.melanchier alnifolia 6.9 1.6 11.8 16.1 34.8 Elaeagnus commutata 6.5 1.0 7.8 9.7 24.0 Shepherdia argentea 3.0 0.9 7.3 12.9 23.2 Total 100.0 13.2 100.0 100.0 300.0 Average all stands Elaeagnus commutata 29.6 10.4 31.0 19.9 80.5 Symphoricarpos occidentalis 26.1 4.9 14.6 18.3 59.0 woodsii 20.4 5.9 17.6 17.3 55.3 Juniperus horizontalis 1.9 2.4 7.2 5.2 14.3 Arctostaphylos uva-ursi 3.0 2.9 8.7 5.4 17.1 Amelanchier alnifolia 9.0 2.4 7.2 14.7 30.9 Prunus virginiana 2.1 0.6 1.8 5.9 9.8 Potentilla fruticosa 5.5 3.0 8.9 7.5 21.9 Shepherdia argentea 0.6 0.2 0.6 1.6 2.8 Juniperus communis 0.3 0.2 0.6 0.8 1.7 Rubus strigosus 0.1 trace trace 0.3 0.4 Clematis ligusticifolia 0.5 trace trace 0.5 1.0 Shepherdia canadensis 0.6 0.4 1.2 1.6 3.4 Salix interior 0.3 0.2 0.6 1.0 1.9 Total 100.0 33.5 100.0 100.0 300.0 57

Table 10. Herbaceous vegetation data from 10 mature stands of riverbottom forest in southwest Alberta. Stand dominants have an importance value of 7.5 or more.

Stand Plants/ Rel. Rel. Rel. Imp. Species sq. m Dens. Dom. Freq. Val. 1. Cook's Ranch Agropyron inerme 10.4 15.6 11.0 14.0 40.6 Stipa columbiana 5.8 8.7 7.8 5.4 21.9 Solidago mollis 4.2 6.3 4.8 7.0 18.1 Selaginella densa 0.4 0.6 14.6 1.6 16.8 0xytt'opi~ viscida 3.0 4.5 6.4 3.9 14.8 Smilacina stellata 3.4 5.1 4.3 4.6 14.0 Senecio canus 3.4 5.1 3.2 5.4 13.7 Agrostis alba 3.6 5.4 2.7 5.4 13.5 Poa pratensis 4.4 6.6 3.7 3.1 13.4 Poa secunda 3.0 4.5 2.3 4.6 11.4 Agropyron trachycaulum 4.6 6.9 1.8 2.3 11.0 Linaria vulgaris 3.2 4.8 3.4 2.3 10.5 Erigeron compositus 2.8 4.2 3.7 2.3 10.2 Penstemon nitidus 1.2 1.8 3.0 3.9 8.7 Chrysopsis villosa 1.8 2.7 2.0 3.1 7.8 Taraxacum officinale 1.4 2.1 2.5 3.1 7.7 Achillea millefolium 1.8 2.7 2.3 1.6 6.6 Antennaria rosea 0.2 0.3 4.6 0.8 5.7 Stipa comata 0.4 0.6 2.7 1.5 4.9 Cirsium arveri.se 0.4 0.6 2.3 1.6 4.5 Glycyrrhiza lepidota 0.6 0.9 1.1 1.6 3.6 0ryzopsis hymenoides 0.6 0.9 0.9 1.6 3.4 Astragalus missouriensis 0.4 0.6 0.9 1.6 3~1 Koeleria cristata 0.4 0.6 0.9 1.6 3.1 Anemone multifida 0.4 0.6 0.9 1.5 3.0 Phleum pratense 0.6 0.9 0.9 0.8 2.6 Zizia aptera 0.4 0.6 0.5 1.5 2.6 Monarda fistulosa 0.4 0.6 0.5 1.5 2.6 Draba aurea 0.4 0.6 0.2 1.6 2.4 Fragaria virginiana 0.4 0.6 0.2 1.5 2.3 Hedysarum alpinum 0.2 0.3 0.9 0.8 2.0 Trifolium repens 0.4 0.6 0.5 0.8 1.9 Agropyron dasystachyum 0.4 0.6 0.5 0.8 1.9 Potentilla gracilis 0.4 0.6 0.5 0.8 1.9 Galium boreale 0.2 0.3 0.5 0.8 1.6 Castilleja miniata 0.2 0.3 0.5 0.8 1.6 Vicia americana 0.2 0.3 0.5 0.8 1.6 Linum lewisii 0.2 0.3 trace 0.8 1.1 Bromus inerme 0.2 0.3 trace 0.8 1.1 Campanula rotundifolia 0.2 0.3 trace 0.8 1.1 Total 66.6 100.0 100.0 100.0 300.0 58 Table 10 (continued) Stand Plants/ Rel. Rel. Rel. Imp. Species sq. m Dens. Dom. Freq. Val. 2. East of Aetna Medicago lupulina 31.6 36.0 44.6 22.9 103.5 Poa pratensis 9.2 10.5 6.2 10.2 26.9 Oxytropis viscida 5.6 6.4 10.8 9.0 26.2 Petalostemon candidum 2.8 3.2 8.2 5.4 16.8 Poa secunda 3.8 4.3 2.2 4.2 10.7 Erigeron compositus . 2.6 3.0 2.6 4.2 9.8 Bu_Eleu.r~ americanum 3.2 3.6 2.5 3.6 9.7 Taraxacum officinale 2.2 2.5 2.3 4.2 9.0 Thermopsis rhombifolia 1.8 2.1 2.2 3.6 7.9 Lupinus argenteus 1.4 1.6 2.2 3.6 7.4 Chrysopsis villosa 1.8 2.1 2.2 3.0 7.3 Solidago mollis 2.2 2.5 1.7 3.0 7.2 Bromus tectorum 4.2 4.8 0.3 1.8 6.9 Achillea millefolium 2.0 2.2 0.8 2.4 5.4 Monarda fistulosa 1.6 1.8 1.9 1.2 4.9 Glycyrrhiza lepidota 0.8 0.9 3.1 0.6 4.6 Poa compressa 1.6 1.8 0.9 1.8 4.5 Agropyron smithii 1.0 1.1 0.2 1.8 3.1 Agropyron trachycaulum 0.8 0.9 0.3 1.8 3.0 Senecio canus 0.8 0.9 0.6 1.2 2.7 Vicia americana 0.6 0.7 0.5 1.2 2.4 Hedysarum boreale 0.2 0.2 1.5 0.6 2.3 Melilotus officinalis 1.4 1.6 0.1 0.6 2.3 Melilotus alba 0.2 0.2 0.3 1.2 1. 7 Linum lewisii 0.8 0.9 0.2 0.6 1. 7 Phleum pratense 1.0 1.1 trace 0.6 1.7 Comandra pallida 0.6 0.7 0.3 0.6 1.6 Bouteloua gracilis 0.4 0.4 0.3 0.6 1.3 Penstemon nitidus 0.4 0.4 0.1 0.6 1.1 Allium textile 0.2 0.2 0.2 0.6 1.0 Smilacina stellata 0.2 0.2 0.2 0.6 1.0 Fragaria virginiana 0.2 0.2 0.2 0.6 1.0 Equisetum arvense 0.2 0.2 0.1 0.6 0.9 Tragopogon dubius 0.2 0.2 0.1 0.6 0.9 Potentilla anserina 0.2 0.2 0.1 0.6 0.9 Total 87.8 100.0 100.0 100.0 300.0

3. Cardwell's Island Poa pratensis 41.4 32.6 23.6 14.7 70.9 Medicago lupulina 11.6 9.1 7.2 7.8 24.1 Monarda fistulosa 6.4 5.0 8.5 6.4 19.9 Antennaria rosea 5.2 4.1 6.6 3.9 14.6 Solidago mollis 6.6 5.2 ' 3.9 5.4 14.5 Poa compressa 8.2 6.5 3.9 3.4 13.8 59

Table 10 (continued)

Stand Plants/ Rel. Rel. Rel. Imp. Species sq. m Dens. Dom. Freq. Val.

Taraxacum officinale 3.6 2.8 3.2 4.9 10.9 Glycyrrhiza lepidota 1.6 1.3 6.0 2.9 10.2 Phleum pratense 3.6 2.8 2.8 4.4 10.0 Oxytropis viscida 3.2 2.S 4.5 2.9 9.9 Fragaria virginiana 3.8 3.0 3.3 3.4 9.7 Viola adunca 2.6 2.1 2.4 3.9 8.4 Anemone multifida 2.4 1.9 2.7 2.9 7.5 Thermopsis rhombifolia 2.2 1. 7 2.2 2.9 6.8 Agropyron inerme 3.6 2.8 1.3 2.4 6.5 Agropyron dasystachyum 3.2 2.S 1.0 2.4 5.9 Zizia aptera 1.6 1.3 1.5 2.4 5.2 Erigeron compositus 1.8 1.4 1. 7 2.0 5.1 Thalictrum venulosum 2.2 1.7 1.7 1.5 4.9 Senecio canus 1.2 0.9 1.3 1.5 3.7 Stipa comata 1.2 0.9 1.2 1.5 3.6 Poa secunda 1.0 0.8 0.8 LS 3.1 Chrysopsis villosa 0.6 0.5 0.9 1.5 2.9 Achillea millefolium 0.8 0.6 0.4 1.5 2.5 Hedysarum alpinum 0.6 0.5 1.0 1.0 2.5 Galium boreale 0.8 0.6 1.3 o.s 2.4. Linum lewisii 0.8 0.6 0.8 1.0 2.4 Smilacina stellata 0.6 o.s 0.4 1.5 2.4 Stipa columbiana 0.8 0.6 0.5 1.0 2.1 Vicia americana 0.6 0.5 0.5 1.0 2.0 Lilium philadelphicum 0.4 0.3 0.5 1.0 1.8 Melilotus officinalis 0.6 0.5 0.3 1.0 1.8 Agrostis alba 0.6 o.s 0.3 0.5 1.3 Lupinus argenteus 0.2 0.2 0.5 o.s 1.2 Bromus ciliatus 0.2 0.2 0.3 0.5 1.0 Campanula rotundifolia 0.2 0.2 0.3 0.5 1.0 Allium textile 0.2 0.2 0.3 0.5 1.0 Erigeron acris 0.2 0.2 0.3 0.5 1.0 Cirsium arvense 0.2 0.2 0.3 0.5 1.0 Tragopogon dubius 0.2 0.2 0.1 o.s 0.8 Total 126.8 100.0 100.0 100.0 300.0

4. Woolford Park Poa pratensis 45.5 34.1 2.2 15.3 51.6 Medicago lupulina 20.3 15.2 12.6 11.8 39.6 Solidago mollis 8.8 6.6 11.5 9.7 27.8 Fragaria virginiana 5.8 4.3 14.8 7.6 26.7 Agrostis alba 11.0 8.2 7.5 4.2 19.9 compressa 10.8 8.1 4.0 6.3 18.4 Glycyrrhiza lepidota 1.8 1.3 10.1 2.8 14.2 Oxytropis viscida 3.5 2.6 6.6 4.9 14.1 60

Table 10 (continued)

Stand Plants/ Rel. Rel. Rel. Imp. Species sq. m Dens. Dom. Freq. Val.

Taraxacum officinale 2.8 2.1 3.7 5.6 11.4 Thermopsis rhombifolia 2.5 1.9 5.8 2.8 10.5 Viola adunca 3.5 2.6 3.0 2.8 8.4 Monarda fistulosa 1.3 1.0 1.8 2.8 5.6 Achillea millefolium 1.5 1.1 1.3 2.8 5.2 Poa secunda 1.5 1.1 1.6 2.1 4.8 Smilacina stellata 1.3 1.0 1.6 2.1 4.7 Agropyron dasystachyum 2.3 1.7 0.8 1.4 ,3.9 Stipa columbiana 1.0 0.7 1.0 2.1 3.3 Antennaria rosea 0.3 0.2 2.6 0.7 3.5 Gaillardia aristata 0.8 0.6 1.3 1.4 3.3 Ranunculus acris 1.0 0.7 0.5 2.1 3.3 Erigeron compositus 0.8 0.6 0.5 2.1 3.2 Galium boreale 0.5 0.4 0.9 1.4 2.7 Petalostemon candidum 0.8 0.6 1.3 0.7 2.6 Equisetum arvense 1.0 0.7 0.6 0.7 2.0 Phleum pratense 1.0 0.7 0.6 0.7 2.0 Agropyron inerme 0.8 0.6 0.6 0.7 1.9 Bromus inermis 0.5 0.4 0.6 0.7 1.7 Linum lewisii 0.3 0.2 0.3 0.7 1.2 Vicia americana 0.3 0.2 0.1 0.7 1.0 Chrysopsis villosa 0.3 0.2 0.1 0.7 1.0 Total 133.6 100.0 100.0 100.0 300.0

5. Town Dam Bromus ·inermis 41.6 32.9 35.1 12.9 80.9 Aster laevis 10.4 8.2 10.7 10.6 29.5 Phleum pratense 13.2 10.4 6.6 5.9 22.9 Smilacina stellata 7.2 5.7 6.0 7.1 18.8 Medicago lupulina 6.4 5.1 3.8 4.7 13.6 Monarda fistulosa 3.2 2.5 3.6 4.7 10.8 Galium boreale 4.8 3.8 2.2 4.7 10.7 Vicia americana 3.6 2.8 2.7 4.7 10.2 Achillea millefolium 4.0 3.2 1.6 4.7 9.5 Poapratensis 6.0 4.7 2.7 1.2 8.6 Linum lewisii 4.0 3.2 1.6 3.5 8.3 Solidago gigantea 2.0 1.6 1.9 4.7 8.2 Poa secunda 4.4 3.5 0.5 3.5 7.5 Lupinus argenteus 1.6 1.3 3.0 2.4 6.7 Agropyron smithii 3.6 2.8 1.4 2.4 6.6 Viola adunca 1.6 1.3 1.1 3.5 5.9 Glycvrrhiza lepidota 1.6 1.3 3.3 1.2 5.8 Fragaria virginiana 1.6 1.3 1.4 2.4 5.1 Oxytropis splendens 0.4 0.3 3.3 1.2 4.8 Medicago sativa 0.4 0.3 2.2 1.2 3.7 Oxytropis viscida 0.4 0.3 2.2 1.2 3.7 Geranium richardsonii 0.8 0.6 0.5 2.4 3.5 61 Table 10 (continued)

Stand Plants/ Rel. Rel. Rel. Imp. ·Species sq. m Dens. Dom. Freq. Val.

Melilotus officinalis 0.8 0.6 0.3 1.2 2.1 Anemone multifida 0.4 0.3 0.5 1.2 2.0 Lithospermum ruderale 0.4 0.3 0.5 1.2 2.0 Hedysarum boreale 0.4 0.3 0.3 1.2 1.8 Taraxacum officinale 0.4 0.3 0.3 1.2 1.8 Vicia sparsifolia 0.4 0.3 0.3 1.2 1.8 Comandra pallida 0.4 0.3 0.1 1.2 1.6 Koeleria cristata 0.4 0.3 0.1 1.2 1.6 Total 126.4 . 100.0 100.0 100.0 300.0

6. Slaughter Hole Chrysopsis villosa 13.6 10.6 22.3 15.6 48.5 Medicago lupulina 22.8 17.8 13.1 16.7 47.6 Poa compressa 26.0 20.2 13.1 12.5 45.8 Bromus tectorum 24.0 18.7 1.0 1.0 20.7 Oxytropis viscida 4.8 3.7 5.8 8.3 17.8 Lupinus argenteus 2.4 1.9 8.7 5.2 15.8 Solidago mollis 4.8 3.7 6.3 3.1 13.1 Poa secunda 4.8 3.7 2.6 5.2 11.5 Melilotus officinalis 2.0 1.6 4.2 5.2 11.0 Aster laevis 4.4 3.4 3.4 3.1 9.9 Thlaspi arvensis 7.2 5.6 0.5 3.1 9.2 Artemisia campestris 1.6 1.2 2.6 4.2 8.0 Achillea millefolium 2.4 1.9 1.0 3.1 6.0 Bouteloua gracilis 0.4 0.3 4.2 1.0 5.5 Agropyron smithii 2.0 1.6 2.1 1.0 4.7 Artemisia biennis 1.2 0.9 1.6 2.0 4.5 Stipa columbiana 0.8 0.6 1.8 2.0 4.4 Euphorbia esula 0.4 0.3 3.1 1.0 4.4 Poa pratensis 0.8 0.6 0.3 1.0 1.9 Thermopsis rhombifolia 0.4 0.3 0.5 1.0 1.8 Anemone multifida 0~4 0.3 0.5 1.0 1.8 Tragopogon dubius 0.4 0.3 0.5 1.0 1.8 Aster pansus 0.4 0.3 0.3 1.0 1.6 Taraxacum officinale 0.4 0.3 0.3 LO 1.6 Total 128.4 100.0 100.0 100.0 300.0

7. Highway 5 Bridge Phleum pratense 18.0 14.2 14.0 13.3 41.5 pratensis 31.2 24.6 11.9 4.1 40.6 Aster laevis 10.8 8.5 10.8 11.2 30.5 Zizia aptera 9.6 7.8 14.0 8.2 30.0 Poa compressa 9.6 7.8 12.3 4.1 24.2 62

Table 10 (continued)

Stand Plants/ Rel. Rel. Rel. Imp. Species sq. m Dens. Dom. Freq. Val.

Achillea millefolium 7.2 5.7 5.3 8.2 19.2 Galium boreale 5.2 4.1 2.4 7.1 13.6 Agrostis alba 4.8 3.8 4.1 4.1 12.0 Monarda fistulosa 4.0 3.2 2.6 4.1 9.9 Fragaria virginiana 3.2 2.5 2.9 4.1 9.5 Chrysopsis villosa 3.2 2.5 1.5 5.1 9.1 Agropyron smithii 4.4 3.5 2.5 3.1 9.1 Lathyrus ochroleucus 2.4 1.9 1.8 5.1 8.8 Koeleria cristata 2.4 1.9 3.8 1.0 6.i Cirsium arvense 1.2 0.9 3.2 2.0 6.1 Medicago lupulina 1.6 1.3 0.8 3.1 5.2 Viola adunca 2.4 1.9 0.9 2.0 4.8 Lupinus argenteus 0.8 0.6 2.3 1.0 3.9 Taraxacum officinale 0.8 0.6 0.5 2.0 3.1 Potentilla gracilis 0.8 0.6 0.9 1.0 2.5 Glycyrrhiza lepidota 0.8 0.6 0.4 1.0 2.0 Camoanula rotundifolia 0.8 0.6 0.2 1.0 1.8 Linum lewisii 0.4 0.3 0.3 1.0 1.6 Comandra oallida 0.4 0.3 0.2 1.0 1.5 Oxytropis sericea 0.4 0.3 0.2 1.0 1.5 Poa secunda 0.4 0.3 0.2 1.0 1.5 Total 126.8 100.0 100.0 100.0 300.0

8. Hillspring Park Poa pratensis 40.8 36.2 25.5 12.4 74.1 Solidago mollis 10.0 8.9 14.4 9.0 32.3 Chrysopsis villosa 5.2 4.6 10.4 7.9 22.9 Agropyron trachycaulum 9.6 8.6 7.9 7.8 23.6 Erigeron compositus 7.2 6.4 5.0 10.l 21.5 Poa compressa 8.4 7.4 4.9 6.7 19.0 Poa secunda 4.4 3.9 2.4 9.0 15.3 Melilotus officinalis 2.4 2.1 5.6 5.6 13.3 Artemisia biennis 1.6 1.4 6.6 3.4 11.4 Achillea millefolium 4.8 4.3 2.2 4.5 11.0 Aster laevis 4.8 4.3 2.9 2.2 9.4 Chrysanthemum leucanthemum 4.8 4.3 2.0 2.2 8.5 Lesquerella alpina 1.6 1.4 1.0 2.2 4.6 Medicago sativa 1.2 1.1 0.7 2.2 4.0 Viola adunca 0.8 0.7 0.8 2.2 3.7 Potentilla gracilis 0.8 0.7 0.8 2.2 3.7 Hedysarum boreale 0.4 0.4 2.0 1.1 3.5 Anemone multifida 0.8 0.7 0.4 2.2 3.3 Fragaria virginiana 0.8 0.7 1.5 1.1 3.3 Artemisia campestris 0.8 0.7 1.0 1.1 2.8 63 Table 10 (continued)

Stand Plants/ Rel. Rel. Rel. Imp. Species sq. m Dens. Dom. Freq. Val.

Liatris punctata 0.4 0.4 1.0 1.1 2.5 Agropyron smithii 0.4 0.4 0.5 1.1 2.0 Draba aurea 0.4 0.4 0.5 1.1 2.0 Erigeron caespitosus 0.4 0.4 0.5 1.1 2.0 Total 112.8 100.0 100.0 100.0 300.0 9. Glenwood Bridge Poa prate~1sis 103.6 63.5 48.4 20.5 132.4 Fragaria virginiana 11.2 6.9 10.1 12.5 29.5 Taraxacum officinale 8.0 4.9 7.6 15.9 28.4 Cirsium arvense 4.8 2.9 9.6 6.8 19.3 Phleum pratense 10.4 6.4 5.1 6.8 18.3 Aster laevis 3.2 2.0 4.4 6.8 13.2 Viola adunca 4.8 2.9 2.0 5.7 10.6 Trifolium repens 5.6 3.4 2.9 2.3 8.6 Zizia aptera 2.8 1.7 1.7 3.4 6.8 Medicago lupulina 2.0 1.2 0.9 4.5 6.6 Cynoglossum officinale 1.2 0.7 2.9 2.3 5.9 Ranunculus acris 1.2 0.7 0.9 3.4 5.0 Chrysanthemum leucanthemum 0.8 0.5 0.7 2.3 3.5 Bromus inermis 1.6 LO 0.5 1.1 2.6 Hackelia americana 0.4 0.2 1.0 1.1 2.3 Vicia sparsifolia 0.4 0.2 0.5 1.1 1.8 Chrysopsis villosa 0.4 0.2 0.3 1.1 1.6 Prunella vulgaris 0.4 0.2 0.3 1.1 1.6 Equisetum arvense 0.4 0.2 0.2 1.1 1.5 Total 163.2 100.0 100.0 100.0 300.0

10. Standoff Stipa columbiana 22.5 18.0 13.3 12.6 43.9 Medicago lupulina 22.0 17.6 8.9 8.4 34.9 Chrysopsis villosa 5.5 4.4 10.3 8.4 23.1 Agropyron smithii 15.0 12.0 6.9 4.2 23.1 Thlaspi arvense 16.5 13.2 2.3 6.3 21.8 Artemisia campestris 3.5 2.8 10.0 7.4 20.2 Oxytropis viscida . 6.0 4.8 7.9 5.3 18.0 Potentilla hippiana 4.5 3.6 6.7 7.4 17.7 Linum lewisii 4.5 3.6 3.2 7.4 14.2 Medicago sativa 3.0 2.4 5.3 4.2 11.9 Phleum pratense 2.5 2.0 4.3 5.3 11.6 Thermopsis rhombifolia 3.5 2.8 1.9 4.2 8.9 Gutierrezia sarothrae 1.0 0.8 4.2 2.1 7.1 Koeleria cristata 2.5 2.0 I 1.1 2.1 5.2 Erigeron caespitosus 2.5 2.0 2.1 1.1 5.2 64

Table 10 (continued)

Stand Plants/ Rel. Rel. Rel. Imp. Species sq. m Dens. Dom. Freq. Val.

Artemisia frigida 2.5 2.0 2.1 1.1 5.2 Hedysarum boreale 0.5 0.4 2.6 1.1 4.1 Monarda fistulosa 1.0 0.8 2.1 1.1 4.0 Comandra pallida 1.5 1.2 0.5 1.1 2.8 Solidago mollis 0.5 0.4 1.1 1.1 2.6 Liatris punctata 0.5 0.4 0.5 1.1 2.0 Astragalus missouriensis 0.5 0.4 0.5 1.1 2.0 Luoinus sericea 0.5 0.4 0.5 1.1 2.0 Townsendia parryi 0.5 0.4 0.5 1.1 2.0 Bouteloua gracilis 0.5 0.4 0.3 1.1 1.8 Achillea millefolium 0.5 0.4 0.3 1.1 1.8 Allium textile 0.5 0.4 0.2 1.1 1. 7 Arabis holboellii 0.5 0.4 0.2 ·1.1 1.7 Total 125.0 100.0 100.0 100.0 300.0

Table 11. Summary of herbaceous species stand dominants based on a minimum importance value of 7.5 or more in at least one stand. Community dominants, designated "CD" in the table, have an average importance value of not less than 7.5 and are dominant in at least four of the ten stands.

Av. No. Stands Comm. Species Imp. Val. Dominant Dom.

Poa pratensis 41.9 8 CD Medicago lupulina 26.3 6 CD Poa compressa 12.1 5 CD Chrysopsis villosa 11.1 5 CD Solidago mollis 10.6 5 CD Phleum pratense 10.4 5 CD Oxytropis viscida 10.1 6 CD Aster laevis 9.3 5 CD Fragaria virginiana 7.5 4 CD B:romus inermis 8.1 1 Taraxacum officinale 6.7 5 Stipa columbiana 6.6 2 Poa secunda 5.6 5 Agrostis alba 4.5 3 Erigeron compositus 4.2 3 Agropvron inerme 4.1 1 Monarda fistulosa 4.1 3 65 Table 11 (continued)

Av. No. Stands Comm. Species Imp. Val. Dominant Dom.

Achillea millefolium 4.0 3 Agropyron trachycaulum 3.5 2 Smilacina stellata 3.3 2 Agropyron smithii 3.2 2 Thlaspi arvense 3.1 2 Zizia aptera 3.0 1 Artemisia campestris 2.8 2 Thermopsis rhombifolia 2.7 3 Viola adunca 2.7 3 Glycyrrhiza lepidota 2.4 2 Galium boreale 2.4 2 Melilotus officinalis 2.4 2 Cirsium arvense 1.9 1 Potentilla hippiana 1.8 1 Petalostemon candidum 1.7 1 Selaginella densa 1.7 1 Lupinus argenteus 1.6 1 Antennaria rosea 1.5 1 Senecio canus 1.4 1 Medicago sativa 1.2 1 Linaria vulgaris 1.1 1 Artemisia biennis 1.1 1 Bupleurum americanum 1.0 1 Vicia americana 1.0 1 Penstemon nitidus 0.9 l Lathyrus ochroleucus 0.9 1 Chrysanthemum leucanthemum 0.9 1 Trifolium repens 0.9 1 Anemone multifida 0.8 1 Solidago gigantea 0.8 1 66 Table 12. Unoccupied space (rock, litter, bare soil) in 10 stands of mature riverbottom forest measured at the herb stratum level.

% Stand U. Sp.

1. Cook's Ranch 65.4 2. East of Aetna 69.8 3. Cardwell's Island 57.0 4. Woolford Park 78.0 5. Town Dam 62.1 6. Slaughter Hole 69.2 7. Highway 5 Bridge 50.6 8. Hillspring Park 79.3 9. Glenwood Bridge 56.8 10. Standoff 65.2

Average 66.2

community. Pursuant to this, to typify the riverbottom forest community on the three streams, characteristics of typical riverbottom forest dominants were derived from the individual stand dominance values based on importance value, plus a somewhat arbitrary judgment that a community dominant must also be a stand dominant in no fewer than four of the ten stands.

In the riverbottom forest of St. Mary River, Lee Creek and

Belly River the most important mature tree was the AB hybrid poplar

(Populus X balsamifera), a dominant in nine of the ten stands and with the highest average importance value for tree species, 110.8. A close second was narrow-leaf cottonwood (f. angustifolia), a dominant in nine of ten stands and with an average importance value 67

Dissimilarity Stands 2 3 4 5 6 7 8 9 10 X • 25 .23 .17 .31 .27 .21 .22 .30 .31 1 9 .so X .17 .26 .39 .32 .33 .20 .38 .43 2 8 .56 .58 X .17 .31 .23 .25 .13 .26 .35 3 s i 7 .45 .66 .58 X .30 .15 .25 .22 .27 .25 4 m 6 .64 .60 .65 .57 X .21 .22 .26 .18 .29 s i 1 5 .56 .67 .59 .63 .64 X .28 .20 .25 .21 6 a 4 .60 .58 .63 .60 .70 .55 X .27 .19 .40 7 r i 3 .50 .59 .72 .60 .62 .54 .68 X .27 .29 8 t 2 .42 .47 .65 .52 .53 .46 .59 .68 X .35 9 y 1 .54 .55 .63 .64 .58 .54 .68 • 62 .60 X 10 9 8 7 6 5 4 3 2 Stands

Stands

1. Cook's Ranch 6. Slaughter Hole 2. East of Aetna 7. Highway 5 Bridge 3. Cardwell's Island 8. Hillspring Park 4. Woolford Park 9. Glenwood Bridge 5. Town Dam 10. Standoff

Figure 14. Similarity and dissimilarity coefficients between ten stands in the riverbottom forest community of southwest Alberta. The maximum probable coefficient of similarity is .85. 68

Table 13. Community similarity and dissimilarity totals for the 10 stands in the riverbottom forest community of southwest Alberta, Canada.

Total Total Stand Diss. Vals. Sim. Vals.

1. Cook's Ranch 2.27 5.38 2. East of Aetna 2.73 4.92 3. Cardwell's Island 2.10 5.5S 4. Woolford Park 2.04 5.61 5. Town Dam 2.47 5.18 6. Slaughter Hole 2.12 S.53 7. Highway 5 Bridge ·2.40 5.25 8. Hillspring Park 2.06 5.59 9. Glenwood Bridge 2.45 5.20 10. Standoff 2.88 4. 77

of 94.5. Third was balsam poplar (P. balsamifera), a dominant in seven of ten stands and with an average importance value of 89.9.

These three trees, a hybrid and its two parent species, identify the tree canopy stratum of the riverbottom forest community on these three streams. Quaking aspen (P. tremuloides) and white spruce

(Picea glauca) are relatively unimportant species in spite of their very high importance in the aspen parkland and montane forest biomes nearby. No distinctive trends or patterns were noted in dominant species change from upstream to downstream stands.

For the tree reproduction stratum within the climax forest stands similar results were obtained. The most important species was narrow-leaf cottonwood, a dominant in eight of ten stands with an average importance value of 118.9. Balsam poplar was second, a 69 dominant in six of ten stands with an av~rage importance value of

90.7. Third was the AB hybrid poplar, a dominant in six of ten stands with an average importance value of 79.1. The three dominant species

in the tree reproduction stratum are the same as the dominant species in the mature forest tree stratum with closely grouped average

importance values and stand-dominant values.

The minor tree species, quaking aspen and white spruce, were also the minor species in the tree reproduction stratum~ Absolute density of tree species ranged from a low density of

122.6 trees per hectare at Site 1 - Cook's Ranch, to a high density of 517.8 trees per hectare at Site 7 - Highway 5 Bridge. Average density of all stands was 283.4 trees per hectare.

Of the six species of clumped shrubs encountered in sampling,

only two occurred in four or more of the ten stands and none in ten of ten. River birch (Betula occidentalis) was the number one dominant

clumped shrub for the riverbottom forest community of this study. It

occurred as a dominant in nine of ten stands and had an average

importance value of 171.8. The other community dominant was red-osier dogwood (Cornus stolonifera), a dominant in seven of ten stands and with an average importance value of 72.1. Yellow willow (Salix lutea) was a dominant in three of ten stands but its average importance value

of 44.5 was too low for consideration as a community dominant. Of the 14 species of thicket shrubs encountered in sampling,

eight were dominants in at least one stand. Only four were judged

community dominants. First was silverberry (Elaeagnus commutata), a

dominant in eight of ten stands and with an average importance value

of 80.5. Second was snowberry (Symphoricarpos occidentalis) occuring 70 in eight of ten stands as a dominant and with an average importance value of 59.0. Third was wood rose {Rosa woodsii), dominant in seven of ten stands, average importance value 55.3. Fourth was serviceberry {Amelanchier alnifolia), a dominant in four of ten stands and with an ave.rage importance value of 30.9.

Nine community dominants were found among the herbaceous species in the ten stands. Forty-nine species. were dominants in at least one stand. The community dominants in descending order followed by frequency of dominance and average importance value are: Poa pratensis, eight of ten, 41.9; Medicago lupulina, six of ten, 26.3;

compressa, five of ten, 12.1; Chrysopsis villosa, five of ten,

11.1; Solidago mollis, five of ten, 10.6; Phleum pratense, five of ten, 10.4; Oxytropis viscida, six of ten, 10.1; Aster laevis, five of ten, 9.3; and Fragaria virginiana, four of ten, 7.5.

All of the dominant tree species and all of the dominant shrub species are native to Alberta. Five of the herbaceous species community dominants are native and four are exotics.

Unoccupied space, measured at the herb stratum level, ranged from a low of 50.6% at Site 7 - Highway 5 Bridge to a high of

79.3% at Site 8 - Hillspring Park. Average unoccupied ground area for all ten sites was 66.2%_{Table 12).

Penetrometer readings throughout the forest stands tended to reflect the sand and silt deposition brought about by earlier over- bank flooding {Table 14). The litter layer, even under the highest density forest at Site 7 - Highway 5 Bridge {517.8 trees per hectare) did not exceed five centimeters. The minimum penetrometer reading at most stands was 0.0 dm and maximum readings_ of 9.0 dm were not 71

Table 14. Penetrometer readings from ten mature stands of riverbottom forest in southwest Alberta, Canada.

Decimeters Site Maximum Minimum Average 1. Cook's Ranch 8.0 o.o 2.3 2. East of Aetna 9.0 o.o 2.1 3. Cardwell's Island 8.0 o.o 2.8 4. Woolford Park 8.0 0.0 3.6 5. Town Dam 7.0 0.0 2.1 6. Slaughter Hole 9.0 o.o 2.2 7. Highway 5 Bridge 9.0 1.0 3.4 8. Hillspring Park 4.0 o.o 1.5 9. Glenwood Bridge 7.0 1.0 3.6 10. Standoff 4.0 o.o 1.4 Average all sites 7.3 0.2 2.5

uncommon. Mean penetration of soil under mature forest was 2.5 dm, in considerable contrast to the 0.4 dm mean obtained from pioneer gravel bar sites.

Soils analysis data from gravel bar, forest and.adjacent grassland sites are summarized in Table 15. The pH of gravel bar soil was very close to 8.0 at all sites with a moderation toward a slightly less alkaline reaction in the forest sites where pH values averaged

7.6 at the surface and 7.8 at a depth of two decimeters. Neighboring grassland soils on terrace three were still more moderate with an average surface pH of 7.5 and a two-decimeter depth pH of 7.7. A decrease in sand and an increase in silt and cl~y fractions occured from gravel bar to forest to grassland, these data complementing penetrometer data. Parts per millio~ of soluble salts increased Table 15. Sunnnary of soils analyses {Bouyoucus, 1936) for 10 mature stands of riverbottom forest, adjacent gravel bars and fescue prairie grasslands in southwest Alberta. 1. = loam, s. = sand

River or stream % sand % silt % clay Type pH ppm salts Site surface 2 dm surface 2 dm surface 2 dm surface 2 dm surface 2 dm surf. 2 dm St. Mary River (1 - 4) Gravel bar 86.9 7.7 5.5 1. s. 8.1 153 Riverbottom forest 67.8 68.5 24.0 22.6 8.3 8.9 s. 1. s. 1. 7.7 7.8 365 337 Fescue prairie 54.6 60.1 35.4 30.0 10.0 9.9 1. s. 1. 7.7 8.0 397 406 Lee Creek {5 - 6) Gravel bar 89.7 5.8 4.5 s. 8.1 174 Riverbottom forest 72.8 70.8 21.5 20.5 5.8 8.8 s. 1. s. 1. 7.6 7.8 464 198 Fescue prairie 58.5 52.0 32.3 38.5 9.3 9.5 s. 1. s. 1. 7.7 7.5 306 334 Belly River {7 - 10) Gravel bar 77.5 13.9 8.6 1. s. 7.9 200 Riverbottom forest 50.4 61.6 35.4 26.8 14.3 11.6 s. 1. 1. s. 7.5 7.9 545 269 Fescue prairie 55.0 62.8 31.3 26.6 13.8 10.6 1. s. 1. 7.1 7.7 524 244 Average all stands Gravel bar 84.7 9.1 6.6 1. s. 8.0 176 Riverbottom forest 63.7 70.0 27.0 23.3 9.5 9.8 s. 1. s. 1. 7.6 7.8 458 268 Fescue prairie 56.0 58.3 33.0 31.7 11.0 10.0 1. s. 1. 7.5 7.7 409 328

...., N 73 markedly, from the gravel bar surface average of 176 ppm, to 458 ppm in forest surface soils, to 409 ppm in grassland surface soils. No analyses were undertaken for organic carbon, total nitrogen or tota1 phosphorous.

An age determination formula was devised to facilitate approximating average tree age and age of largest tree in each stand. (d - bd) The basic formula was: Age in years= r 5; where .!!_equals 2 + the diameter in centimeters of the tree trunk at 1.4 meters: above ground, b equals the fraction of the diameter that is bark,!:. the average number of annual rings per centimeter of xylem, and "plus 5" is an approximation of the number of years the tree took to reach a height of 1.4 meters. Values for band r were constructed through the use of an increment borer, with no fewer than 20 samples being taken for each tree species throughout the range of the ten study sites.

For narrow-leaf cottonwood b equals 0.2 and!:. equals 3.74; for balsam poplar b equals 0.184 and!:. equals 3.70; for the AB hybrid poplar b equals 0.193 and.!. equals 3.78; and for quaking aspen b equals 0.073 and.!. equals 5.5. Values for band r were not determined for white spruce. Bark thickness for the AB hybrid poplar was intermediate between those of its parent species and growth rate of the AB hybrid was slowest of the three. Average diameter and approximate age of tree species in the ten stands sampled, plus the approximate ag~ of the largest sampled tree per stand are given in Table 16.

Smallest average diameter and lowest average age species was narrow-leaf cottonwood whose average diameter was 20.8 cm and average age was 36 years for all stands.· Second oldest species was balsam poplar with an average diameter of 21.8 cm and average age of 38 74

Table 16. Average diameter and age, and largest diameter and age, of mature trees in 10 stands of riverbottom forest in southwest Alberta.

Stand Cm Largest tree Species Diam. Age Cm Diam. Age

1. Cook's Ranch Po2ulus angustifolia 15.0 27 36 58 P. balsamifera 15.2 28 P. X balsamifera 15.5 29

2. East of Aetna P. angustifolia 12.0 23 P. balsamifera 13.5 25 P. X balsamifera 17.8 32 31 51

3. Cardwell's Island P. an~stifolia 29.0 48 P. balsamifera 19.1 34 P. X balsamifera 28.2 48 46 75 P. tremuloides 10.7 32

4. Woolford Park P. an~stifolia 23.9 41 51 81 P. balsamifera 9.7 20 P. X balsamifera 24.6 43 51 82

5. Town Dam P. angustifolia 23.4 40 P. balsamifera 22.6 39 P. X balsamif era 34.3 57 76 121

6. Slaughter Hole P. angus tifolia 15.5 28 P. balsamifera 21.8 38 P. X balsamifera 23.4 41 38 63 7. Highway 5 Bridge P. angustifolia 26.2 44 P. balsamif era 22.4 39 48 78 P. X balsamifera 18.0 32 P. tremuloides 13.2 38 8. Hillspring Park P. angustifolia 26.4 45 P. balsamifera 35.3 58 7S Table 16 (continued)

Stand Cm Largest tree Species Diam. Age Cm Diam. Age

P. X balsamifera 44.7 73 89 141

9. Glenwood Bridge P. angustifolia 14.0 23 P. balsamifera 31.2 52 P. X balsamifera 29.0 49 56 90 10. Standoff P. angustifolia 22.4 38 P. balsamifera 27.9 47 P. X balsamifera 26.7 47 36 59 Average all stands P. angustifolia 20.8 36 43 69 P. balsamifera 21.8 38 48 78 P. X balsamifera 26.2 45 53 85 P. tremuloides 12.0 35

years. The AB hybrid poplar had the largest average diameter, 26.2 cm, and the highest average age, 45 years.

Narrow-leaf cottonwood was the largest tree sampled in two stands. Largest diameters of 36 and 43 cm for this species were found in two stands. Corresponding ages were 58 and 69 years.

Balsam poplar was the largest tree sampled in one stand. This tree,

48 cm in diameter, was 78 years old. The AB hybrid poplar was the largest tree sampled in eight stands. The average diameter of these large poplars was 53 cm and av~rage age 85 years. The largest tree in any sample, an AB hybrid, was 89 cm in diameter with an age of

141 years. The average age of the largest trees sampled in the stands was 40 years.

A search was conducted on each of the three streams for very 76 large, and presumably, very old trees. These would provide some indication of the possible age attainment of dominant tree species.

Through actual increment boring the oldest tree found was an AB hybrid poplar on Lee Creek three kilometers below Beazer that was, in 1973, 250 years old. Another large AB hybrid, with a diameter of 129 cm and approximate age of 200 years, was found at the Kearl Ranch on Lee Creek, five kilometers southwest of Cardston (Figure 15). Other large trees in Kearl's private picnic ground (Figure 12) were a narrow-leaf cottonwood 160 years old, and a balsam poplar 100 years old.

The largest tree found on St. Mary River, near Woolford Park, was an AB hybrid poplar with a 102 cm diameter at 1.4 m height above ground and an approximate age of 160 years (Figure 16). Nearby was a balsam poplar 97 cm in diameter and approximately 155 years old.

Height of the large trees ranged from 13 to 22 meters. At no site were trees tall enough to project much above the valley rim.

A composite climatogram of mean temperatures and precipitation from the weather station at Cardston, a central point in the study area, and streamflow rates for St. Mary River near the International

Boundary is .correlated with important riverbottom forest events

(Figure 17). Time of any event may vary from year to year, but plant activity along the three streams has evolved to conform to an average frost-free period of 100 days at Cardston, 95 days at Sites 1 and 7, and 102 days at Site 10 (Hardy, 1967).

First leaf-out of tree species began at Site 10 - Standoff on May 13 in 1972. One week later tree leaf-out was beginning on the upper St. Mary River at Site 2 - East of Aetna, on Lee Creek at Site

5 - Town Dam, and at Site 8 - Hillspring Park on Belly River. 77

Figure 15. Populus angustifolia X balsamifera, dbh 129 cm and approximate age 200 years. Lee Creek at Kearl Ranch, SW Cardston, Aug., 1972. 78

Figure 16. Populus angustifolia X balsamifera at Woodgrove Park, St. Mary River. Stem at the left has dbh 102 cm and approximate age of 160 years, November, 1973. 79

Flow Temp Cu. m/ cm precip. c. sec. 36 36 108 34 32 102 32 28 96 30 24 90 28 20 84 26 16 78 24 12 72 22 8 66 20 4 60 18 0 54 16 -4 48 14 -8 42 12 -12 36 10 -16 30 8 -20 24 6 -24 18 4 -28 12 2 -32 6 0 -36 0

JFMAMJJA SOND

Figure 17. Composite of mean monthly precipitation, temperature and streamflow correlated with important riverbottom forest events. Precipitation and temperature are from the Cardston weather station; streamflow is for St. Mary River near the International Boundary. Bar graph= precipitation; solid line= temperature; broken line= streamflow. 80

Leaf-out was not simultaneous at any one site for all poplar species. For example, on May 14 of 1972 balsam poplar and pre-vernal aspen were leafing out at Site 10 - Standoff. By May 18 the same species were beginning leaf-out at Site 4 - Woolford Park. The AB hybrids were just beginning leaf-out at Site 10 - Standoff on May 21, and at Site 4 - Woolford Park on May 28. By May 21 narrow-leaf cottonwoods were leafing out at Site 10 - Standoff, but had not yet begun to do so at Site 4 - Woolford Park nor at any sites upstream from there. Leaf-out sequence of community tree dominants at any given site if first, balsam poplar; second, the AB hybrids; and third, narrow-leaf cottonwood (Figure 18).

The shrub species followed a leaf-out sequence that began, in

1972, on May 21 at Site 10 - Standoff and worked from there upstream and toward the mountains on all stream sites. Woody plant leaf-out progressed upstream at the rate of five river kilometers per day under mild weather conditions.

The importance of riverbottom forest to man in the early days of the Canadian west was variable. Certainly use of the forest for shelter and firewood was made by aboriginal man. Prior to 1877 this part of the northern great plains was controlled by Indian tribes of the Blackfeet Confederacy. Ewers (1958) reported that Indian use of riverbottom forest was principally limited to the winter season when:

In late October or early November the band chief selected a winter campsite in a broad valley sheltered from winds and snow by the high natural walls of the valley itself. The valley floor afforded grass for the horses. The river itself offered clear, cold drinking water, and the cottonwood groves bordering the stream provided firewood. As colder weather arrived in late November or early December men and women cut out the underbrush and some of the trees and moved their lodges into the timber. The standing trees served as wind- 81

break and snow fence. Unless food became scarce or the wild grass for the horses was exhausted they remained in this locality throughout the winter.

Evidence of such encampments, in the form of "tepee rings,"

rocks of four to fourteen kilograms weight used to hold down the

lower edge of the lodge cover and left in their circular formation,

was found at or near Site 1 - Cook's Ranch, Site 2 - East of Aetna,

and Site 7 - Highway 5 Bridge (Figurt 19).

Ewers (1958) also reported the feeding on the inner bark of

cottonwood trees to horses when snow was too deep for grassland

feeding.

Walter McClintock (1910), who lived with the Blackfeet

Indians from 1896 to 1900 wrote that the Indian name for St. Mary

River meant "Green Banks" because of its gallery forests of poplars.

He also reported riding through groves of large cottonwoods along

Belly River.

Between 1870 and 1900 many settlers arrived from eastern

Canada and the United States to take up homesteads offered by the

Canadian Government. Many of these people came from forested

regions and to feel more at home they settled in the river valleys,

occasionally in the riverbottom forest itself. The fates of the

first North West Mounted Police detachments at Fort Macleod and St.

Mary Crossing have been mentioned in the introduction.

The town of Cardston, founded in 1887 by Charles Ora Card

from Cache Valley in Utah, was built in part of the riverbottom

forest of Lee Creek. Phqtographs, too faded for reproduction here,

taken of Cardston during the period 1887 to 1900 show the riverbottom forest in much the same position and with the same general 82

Figure 18. Tree leaf-out at Site 4 - Woolford Park in May, 1972. Leafed-out tree to the right is a balsam poplar; half leafed-out trees in the background are AB hybrids; the unleafed-out trees to the left are narrow-leaf cottonwoods.

Figure 19. Faintly visible in the grass are several large stones set in the form of a circle, the "tepee ring" of the plains Indians. Site 1 - Cook's Ranch, St. Mary River. August, 1972. 83 appearance as today (Macleod, 1900). Major floods of 1889, 1903 and 1964 taught the residents about the hazards of living in riverbottom forest.

Settlers in southwest Alberta reported that cottonwood logs made poor building material, being crooked and subject to early decay. Lumber of quality could not be cut from them. Cottonwood made poor firewood; the logs tended to smoulder rather than burn and smaller branches burned too quickly. Building logs, lumber, and shingles came from the forests of spruce and pine on lower mountain slopes twenty miles to the southwest. Coal was found in abundance, further reducing the need for trees as fuel (Hudson, 1963).

A cottonwood log cabin built in 1885 on Lee Creek by E. N.

Barker has long since rotted away and no trace of its logs remains.

Cabins built of pine and spruce logs at the same time still stand

(Barker, 1937).

In 1896 Collector of Customs Frederick D. Shaw, an immigrant from wooded Nova Scotia, built his beautiful home "Woodgrove Park" in a mature stand of riverbottom forest on a second terrace of St.

Mary River east of Cardston (Figure 13). Within ten years the home had to be abandoned and was ultimately destroyed by the river, which had initially seemed far enough away for safety (P.C. Shaw, personal communication).

The writer's grandfather, Vernon S. Shaw, remarked in the early 1950's that the huge (AB hybrid) cottonwood at the Kearl

Ranch on Lee Creek (Figure 15) seemed just as large to him when he was a boy in 1885 as it did at present. This tree, estimated to be

200 years old in 1973, would have been about 114 years old in 1885 84 and a very large tree even then.

Today, of thirteen ranch homes in the Lee Creek valley, only one is built in riverbottom forest on a second terrace and that one is protected from flood damage by a road serving as a dike. Of the fourteen ranch homes on St. Mary River between the International

Boundary and St. Mary Reservoir not one is built in riverbottom forest. Along Belly River three out of ten ranch homes and several homes on the Blood Indian Reservation at Standoff are in riverbottom forest and are annually in danger of flood damage.

During the years from 1950 to 1970 provincial and municipal boards established picnic and camp grounds at four riverbottom forest sites. On St. Mary River parks were established at Kimball and Woolford, on Belly River at a site near Hillspring, and on Lee

Creek at Cardston. Woolford Park has been subjected to frequent and serious flood damage with over half of the original acreage on the second terrace lost to river erosion in spite of attempts made to divert the river. Streambank stabilization using broken concrete sidewalk slabs has been necessary at the Cardston park to prevent erosional loss. Hillspring Park is protected from flood damage by the United Irrigation District diversion dam.

Preservation of intact riverbottom forest has been fortuitous.

Throughout the years of this study, 1970 to 1973, observations of a general nature were made on common bird and mammal species of the riverbottom forest. The most frequently sighted birds, in the order in which they appear in Salt and Wilk (1958), were great blue heron, red-tailed hawk, killdeer, spotted sandpiper, California gull, ring- 85 billed gull, mourning dove, great horned owl, common nighthawk, kingfisher, red-shafted flicker, black-billed magpie, connnon crow, house wren, catbird, robin, starling, yellow warbler, house sparrow and

American goldfinch. The black-billed magpie is the most typical bird of the riverbottom forest.

The most frequently sighted native mammals, in the order in which they appear in Soper (1964), were white-tailed prairie hare,

American varying hare, Black Hills cottontail rabbit, pale striped ground squirrel, buff-bellied chipmunk, Canada beaver, white-footed mouse, meadow vole, jumping mouse, porcupine, northern plains skunk, mule deer and white-tailed deer.

The past importance of the bison on the northern great plains has been described by many authors. At present no natural populations of bison are found in southwest Alberta. Evidence of the former occupancy of riverbottom forest by bison is now found in bone piles beneath steep banks. These were the "buffalo jumps" of the plains Indians. Buffalo were driven over the steep banks to their death below and the meat was used to feed the band of Indians for as long as it would last. Such bone piles were found at Site 2

- East of Aetna, Site 5 - Town Dam, and at three other locations on the study streams.

A personal observation is that beaver and both species of deer have effected a strong population increase during the past 30 years in southwest Alberta. Many stands of riverbottom forest were found to be utilized to some extent by beaver populations unknown on the streams prior to the 1950's (Figure 20). Throughout the course of vegetational surveys in this study small herds of deer, usually 86

Figure 20. Beaver utilization of the riverbottom forest at Site 5 - Town Dam on Lee Creek. All of this cutting was done during 1972. By summer, 1973, many of the stumps had multiple sucker re-growth. 87 one to five animals, were observed in each of the major riverbottom forest stands. Equal numbers of mule and white-tailed deer were seen~ though the two species did not herd together. Taxonomic Treatment

Vascular plants were collected at the ten major study sites, and at nine minor sites on St. Mary River, Lee Creek and Belly River during the growing seasons of 1970, 1971, 1972 and 1973. Plants included as riverbottom forest species were collected from pioneer forest sites on gravel bars and from the riverbottom forest - fescue prairie grassland transition as well as from the area of major interest the mature riverbottom forest.

The southwest Alberta riverbottom forest community contained

294 species of vascular plants in 165 genera representing 50 plant families. Of these, 44 are woody plant species and the remaining 250 are herbaceous plant species.

Voucher specimens of all species are deposited in the Brigham

Young University Herbarium (BRY).

The most important plant families represented were:

Compositae, 30 genera, 61 species; Leguminosae, 12 genera, 39 species;

Gramineae, 16 genera, 28 species; Rosaceae, 8 genera, 16 species;

Salicaceae, 2 genera, 16 species or species hybrids; and Umbelliferae,

8 genera, 12 species.

One species new to the province of Alberta was found. Prunus nigra Ait. was collected in 1971 from a small population on Lee Creek at Site 6 - Slaughter Hole (Shaw 1218). In the fourth (1949), fifth

(1956) and sixth (1961) editions· of Native Trees of Canada, Canada

Plum (Prunus nigra) was reported from New Brunswick west into Manitoba. 89

It was also reported from" ••• fords of several rivers in southern

Alberta." The seventh edition (Hosie, 1969) made no mention of the

Alberta report. This, according to T.C. Brayshaw (personal communi-

cation), was deleted because no specimens could be found to substantiate the report. This report of Prunus nigra in southwes~.

Alberta is now verified (Cody and Shaw, 1973). Range extensions for 13 species were obtained from the

collection data of this study, these being noted in the species list.

The families, genera and species of plants collected on riverbottom forest sites during the study years are included in the key.

Following each species name a statement, after Moss (1959).

of the Alberta distributional status of the species is given. A

second statement gives one site per study stream where the species was collected, and this is followed by a collection number citation. in the same order as the stream citations, for the species.

Plants listed as coming from the Standoff site on Belly River may have actually been collected on the Waterton River. The Standoff

site at the confluence of these two rivers was a very large site with

an area of five square kilometers. The riverbottom forest cited as

Site 10 - Standoff was continuous for three kilometers upstream on each

river from the confluence.

The Divisions, Classes and Sub-Classes are in phylogenetic

sequence after Moss (1959). Families, genera and species follow in

the order in which they appear in the key. KEYSAND DISTRIBUTIONS

Key to the Families of Plants

1. Plants without flowers and seeds, reproducing by spores in

sporangia • • • • • ••• DIVISION I. PTERIDOPHYTA,p. 90

1. Plants reproducing by flowers and seeds

DIVISION II. SPERMATOPHYTA,p. 91 . . 2

2. Seeds borne on open bracts or scales; stigma

wanting ••• CLASS I. GYMNOSPERMAE~p. 91

2. Seeds borne in a closed ovary; stigma present

CLASS2. ANGIOSPERMAE,p. 91 ••• 3

3. Cotyledons usually 1; stems endogenous; veins of the

leaves mostly parallel; floral parts usually in

threes SUBCLASSI. MONOCOTYLEDONEAE,p. 91

3. Cotyledons usually 2; stems exogenous; leaves usually

net veined; floral parts commonly in fours or

fives SUBCLASS2. DICOTYLEDONEAE,p. 92

DIVISION I. PTERIDOPHYTA

1. Leaves br?ad, usually more than 2 cm long, often quite

large, variously incised or dissected

1. Polypodiaceae, p. 100

1. Leaves slender, often scale-like, simple, sessile, mostly small • • • • • • ·• • • ...... • • 2 2. Stems conspicuously jointed and hollow; leaves scale-like 91

in sheath-like whorls at the nodes; spore cases on

the scales of terminal cone-like spikes

2. Equisetaceae, p. 100

2. Stems not as above; leaves mostly imbricated;

spore-cases in cone-like spikes or otherwise

3 •. Selaginellaceae, p. 101

DIVISION II. SPERMATOPHYTA

CLASSI. GYMNOSPERMAK

Only one family represented 4. Pinaceae, p. 101

CLASS2. ANGIOSPERMAE

SUBCLASS1. MONOCOTYLEDONEAE

1. Perianth lacking, or inconspicuous, often of bristles or scales, not petal-like ...... • • • 2 1. Perianth of 2 distinct whorls, the inner often petal-like and conspicuous •• ...... • • • 4 2. Flowers not enclosed in scales; plants not grass-like 5. Typhaceae, p. 103

2. Flowers enclosed or subtended by scales (glumes);

plants grass-like with jointed stems; sheathing leaves and 1-seeded fruit . . . . . • • 3 3. Stems usually hollow, terete or flattened; leaves 2-ranked;

leaf-sheaths usually spl·it; anthers attached at the

middle • • • • • • • • • • • • • • • • • 6. Gramineae, p. 103 92

3. Stems solid, usually more or. less 3-sided; leaves usually

3-ranked; leaf-sheaths not split; anthers attached

at the base •••••••••••••• 7. Cyperaceae, p. 112

4. Perianth relatively inconspicuous, green or brownish;

plants rush-like. • • ••••• 8. Juncaceae, p. 113

4. Perianth conspicuous, at least the inner whorl brightly colored •• . . . . • • • 5 5. Carpels numerous, in a ring or cluster, becoming achenes;

plant of marshes and bogs ••••• 9. Alismaceae, p. 114

5. Carpels 3, their ovaries united; fruit a capsule or

berry •••• ...... • • • • • • 6 6. Ovary superior (rarely partly inferior) 10. Liliaceae, p. 114 6. Ovary inferior •••••• ...... • • 7 7. Flowers regular; stamens 3 . . . . . 11. Iridaceae, p. 116 7. Flowers very irregular; stamens 1 or 2

12. Orchidaceae, p. 117

SUBCLASS2. DICOTYLEDONEAE 1. Corolla none; calyx present or lacking •• . . . . • • • 2 1. Corolla and calyx both present ••••• • 3 2. Plants monoecious or dioecious; staminate and pistillate

flowers, one or both kinds in catkins or dense

heads • • • • • • • • • • • Group I, p. 93

2. Plants mostly with perfect flowers and these not in

catkins (often in dense clusters) •••• Group II, p. 93 3. Corolla of separate petals ...... • • • • • • • • 4 93 3. Corolla with petals more or less united •••• . . . . • • • 5 4. Stamens usually numerous, at least more than 10, and

more than twice as many as the sepals or calyx-

lobes • • • • • • • • • • • • • Group III, p. 94

4. Stamens not more than twice as many as the petals

Group IV, p. 95

5. Stamens more numerous than the corolla-lobes ••• Group V, p. 98

5. Stamens not more numerous than the corolla-lobes

Group VI, p. 98

Group I 1. Staminate or pistillate flowers (not both) in catkins or

catkins-like heads; herbs ••••••• 13. Urticaceae, p. 118

1. Staminate and pistillate flowers both in catkins or catkin-like heads; trees or shrubs . . . . • • 2 2. Ovary becoming a many-seeded capsule; seeds hairy-tufted

14. Salicaceae, p. 118

2. Ovary becoming a 1-seeded nut or winged nutlet

15. Betulaceae, p. 123

Group II

1. Ovary or its locules with many ovules 2

1. Ovary or its locules with only 1 or 2 ovules • 4

2. Ovaries 2 or more, separate 16. Ranunculaceae, p. 123 2. Ovary single . . • • 3 3. Leaves compound 16. Ranunculaceae, p. 123 3. Leaves simple...... 17. Caryophyllaceae, p. 126 94 4. Pistil of more than one carpel; carpels separate or

nearly so ••••••••••• 16. Ranunculaceae, p. 123

4. Pistil solitary, simple or compound •••••••••••• 5

5. Ovary superior; flower hypogynous •••••••••••••• 6

5. Ovary inferior or partly so, or so closely enclosed by the calyx as to appear so ••• ...... • 9 6. Stipules (ocreae) sheathing the stem at the nodes

18. Polygonaceae, p. 127

6. Stipules, if present, not sheathing the stem •••••••• 7

7. Trees or shrubs. • • • • • • • • • • 19. Aceraceae, p. 128

7. Herbs • • • • • • • • • • • • • • • • . • . . • • • • • 8

8. Style (if any) 1 and stigma 1 13. Urticaceae, p. 118 8. Styles 2-3 or of 2-3 branches 20. Euphorbiaceae, p. 128

9. Shrubs or small trees; leaves scurfy; calyx not

corolla-like • • • • • 21. Elaeagnaceae, p. 128

9. Herbs; calyx corolla-like. • • • • 22. Santalaceae, p. 129

Group III l. Ovary superior; flowers hypogynous or epigynous • • • 2 1. Ovary inferior; flowers epigynous ••••••• . . . • 8 2. Carpels few-numerous, entirely separate or united

only at the base • • • • • • • • • • • • • • • • • • • • 3

2. Carpels solitary, or few-several with their ovaries completely united ...... • • • • 5 3. Ovaries cohe~ing in a ring around a central axis;

filaments united into a tube ••••• 23. Malvaceae, p. 129 3. Ovaries and filaments not as above ...... • • 4 95

4. Stamens inserted below the ovaries; leaves without

stipules •••••••••••• 16. Ranunculaceae, p. 123

4. Stamens inserted on a hypanthium or on a disk;

leaves commonly stipulate •••••• 24. Rosaceae, p. 129 5. Ovary simple, 1-loculed • • • • • • • • • • • . . . • • 6 5. Ovary compound as shown by the number of its locules,

placentae, styles or stigmas • • • • • 7

6. OVules 2; seed solitary; fruit a drupe

Prunus in: 24. Rosaceae, p. 129

6. Ovules numerous; leaves compound •• 16. Ranunculaceae, p. 123

7. Ovary several-loculed ••••••••• 23. Malvaceae, p. 129

7. Ovary 1-loculed; placenta parietal 25. Capparidaceae, p. 135 8. Coarse herbs, rough-hairy . . . . . 26. Loasaceae, p. 135 8. Shrubs or trees, not rough-hairy; stems sometimes

with stout spines •••••••••• 24. Rosaceae, p. 129

Group IV

1. Stamens of the same number as the petals and opposite

them 27. Primulaceae, p. 135 1. Stamens not of the same number as the petals, or if of the same number alternate with them ...... • • • 2 2. Ovary superior; flowers hypogynous or perigynous. • 3 2. Ovary inferior; flowers epigynous ...... 22 3. Ovaries 2 or more, wholly separate or somewhat united. • • 4

3. Ovary 1 (simple or compound) • • • • • • • • • • • • • • • 9 4. Stamens inserted at the base of the ovary on the

receptacle. • • • • • • 5 96

4. Stamens inserted on the perianth or on a hypanthium...... • • • • • • • 7 5. Carpels more or less united, with a common style; ovary 5-lobed •••• . . . . . 28. Geraniaceae, p. 136 5. Carpels quite separate or united only at the base, each several-seeded. . . . • • 6 6. Leaves fleshy, entire ...... • 29. Crassulaceae, p. 137 6. Leaves not fleshy, usually lobed or compound 16. Ranunculaceae, p. 123

7. Plants fleshy; stamens just twice as many as

the carpels •••••• 29. Crassulaceae, p. 137

7. Plants not fleshy; stamens not just twice as many as the carpels ...... • • 8 8. Stipules present...... • 24. Rosaceae, p. 129 8. Stipules absent ...... 30. Saxifragaceae, p. 137 9. Ovary simple, with 1 parietal placenta and 1 style. . . . . 31. Leguminosae, p. 138 9. Ovary compound as shown by the number of its locules, placentae, styles or stigmas ...... 10 10. Ovary 1-loculed. 11 10. Ovary 2-several-locµled...... 17 11. Corolla quite irregular 32. Violaceae, p. 149 11. Corolla regular or nearly so ...... 12 12. Fruit 1-seeded ...... 13 12. Fruit with more than 1 seed ...... 14 13. Shrubs or herb with woody base . . 33. Anacardiaceae, p • 149 1~. Herbs . . . . . • ...... 34. Cruciferae, P• 149 97 14. Placentation central ...... 17. Caryophyllaceae, p. 126 14. Placentation parietal...... 15 15. Stamens 4, 5, 8 or 10; petals 4 or 5

30 Saxifragaceae, p. 137

15. Stamens 6; petals 4 16

16. Stamens essentially equal; pod stipitate

25. Capparidaceae, p. 135

16. Stamens unequal, 2 shorter than the other 4; pod sessile ...... •• 34. Cruciferae, p. 149 17. Stamens 6; petals 4; ovary 2-loculed ••• 34. Cruciferae, p. 149 17. Plants not as above ...... 18 18. Ovules and seeds 1 or 2 in each locule ...... 19 18. Ovules and usually the seeds several-many in each locule ...... 21 19. Flowers unisexual, borne in a calyx-like involucre;

plants with milky juice •••••• 20 Euphorbiaceae, p. 128

19. Flowers perfect; plants with watery juice 20

20. Capsule rounded, splitting from the top, 10-seeded

35. Linaceae, p. 153

20. Capsule long-beaked, splitting from below upward

into 5 parts, each I-seeded 28. Geraniaceae, p. 136 21. Styles 2-5; leaves opposite . . 17. Caryophyllaceae, p • 126 21. Style 1 ...... 36. Pyrolaceae, P• 153 22. Ovules and seeds 1 in each locule ...... • . . . . 23 22. Ovules and seeds more than 1 in each locule 26 23. Stamens 5 or 10 ...... 24 23. Stamens 4 or 8 ...... • . . . . . • . . . . . 25 98 24. Shrubs or small trees . . • Crataegus in: 24. Rosaceae, p • 129 24. Herbs . • ...... 37. Umbelliferae, p • 153 25. Fruit a drupe; style and stigma l; large shrub or small herb ...... 38. Cornaceae, p • 157 25. Fruit a capsule or nut-like; herbs . . 39. Onagraceae, p • 157 26. Ovary 1-loculed . . Ribes in: 30. Saxifragaceae, p • 137 26. Ovary 2-many-loculed ...... 27 27. Style 1; stamens 4 or 8 ...... 39. Onagraceae, p • 157 27. Styles 2-3; stamens 5 or 10 . . . . . 30. Saxifragaceae, p. 137

Group V

1. Ovary 1-loculed; corolla irregular; placentae

parietal 31. Leguminosae, p. 138

1. Ovary 3-several-loculed • • 2

2. Filaments united into a tube. 23. Malvaceae, p. 129

2. Filaments free from each other. 40. Ericaceae, p. 159

Group VI

1. Stamens opposite the corolla-lobes and of the same number ...... 27. Primulaceae, p. 135 1. Stamens alternate with the corolla-lobes and of the

same number, or fewer. 2

2. Ovary superior. • • • 3

2. Ovary inferior; flowers epigynous •••••••••••• 14 3. Corolla irregular (zygomorphic) • ...... • 4 3. Corolla regular. . . • 5 4. Ovules solitary in the locules; ovary separating at 99

maturity into 2 or 4 nutlets ••••• 41. Labiatae, p. 160

4. Ovules 2-many in each locule; ovary not separating

into nutlets ••••••••• 42. Scrophulariaceae, p. 161

5. Stamens fewer than the lobes of the corolla 42. Scrophulariaceae, p. 161

5. Stamens as many as the corolla lobes • • 6

6. Carpels 2, separate except sometimes at the apex; herbs with milky juice ...... 43. Apocynaceae, p. 163 6. Carpels united; plants without milky juice ••• . . . • • • 7 7. Ovary deeply 4-lobed, at maturity separating into 2 or 4

nutlets ••••• • 8 7. Ovary not deeply 4-lobed ...... 9 8. Leaves alternate; stem usually rounded; flowers

mostly regular •••••••••• 44. Boraginaceae, p. 163

8. Leaves opposite; stem usually 4-sided; flowers

mostly irregular. • • • • • • • 41. Labiatae, p. 160

9. Ovary 1-loculed • • • • • • 45. Gentianaceae, p. 166

9. Ovary 2-10-loculed • • • • • ••••••••••••• 10

10. Stamens free from the corolla or nearly so 40. Ericaceae, p. 159 10. Stamens inserted on the corolla-tube ...... 11 11. Stamens 4 ...... 12 11. Stamens 5 ...... 13 12. Fruit a capsule, many-seeded •• 42. Scrophulariaceae, p. 161

12. Fruit of 2 or 4 nutlets. • • • • 41. Labiatae, p. 160

13. Fruit of 2 or 4 nutlets; somewhat 4-lobed . . . . . • 44. Boraginaceae, p. 163 100 13. Fruit a capsule or berry; ovary not 4-lobed

46. Polemoniaceae, p. 167

14. Stamens free from the corolla. 47. Campanulaceae, p. 167 14. Stamens inserted on the corolla...... 15 15. Ovary with 1 fertile locule; calyx often modified as

a pappus; flowers in involucrate heads

48. Compositae, p. 167

15. Ovary with 2-many fertile locules and 2-many ovules;

calyx not modified as a pappus or other special structure; flowers not in an involucrate head...... 16 16. Shrubs (erect or climbing), or trailing plants;

stems rounded; leaves opposite, not stipulate

49. Caprifoliaceae, p. 189

16. Herbs; stems mostly 4-sided; leaves opposite

or appearing whorled (the stipules often large

and leaf-like) ••••••••••• 50 Rubiaceae, p. 190

DIVISION I. PTERIDOPHYTA

1. POLYPODIACEAE-FERN FAMILY

1. Cystopteris Bernh. Bladder Fern 1. Cystopteris fragilis (L.) Bernh. Moist ledges and slopes; throughout Alberta. Coalmine Coulee on St. Mary River. (Shaw 1432).

2. EQUISETACEAE-HORSETAIL FAMILY

1. Equisetum L. Horsetail

1. Stems annual; often with many whorls of branches; cones

rounded or acute at apex, without a rigid point 101

1. Equisetum pratense

1. Stems evergreen, unbranched or sparingly so; cones

with a rigid apical point •• 2. Equisetum laevigatum

1. Equisetum pratense Ehrh. Stream banks, thickets and moist woods throughout Alberta. Highway 5 Bridge on Belly River. (Shaw

1854).

2. Equisetun laevigatum A. Br. Meadows, banks and low prairie grassland. Cardwell's Island on St. Mary River. (Shaw 194S).

3. SELAGINELLACEAE-CLUB-MOSS FAMILY

1. Selaginella Beauvois Little Club-moss

1. Selaginella densa Rydb. Commonon dry prairie. Cook's

Ranch on St. Mary River.

DIVISION II. SPEBMATOPHYTA

CLASSI. GYMNOSPERMAE 4. PINACEAE-PINE FAMILY

1. Leaves scale-like or awl-shaped, usually much less than

1 cm long, opposite or whorled, often overlapping; shrubs or small trees •• ...... 1. Juniperus 1. Leaves needle-like or linear, usually more than 1 cm

long, alternate or clustered; trees • • • • 2 2. Leaves in groups of 2 or more ...... • • 2. Pinus

2. Leaves borne singly on the branches e dt e e • • • 3

J. Leaves 4-sided, sharp-pointed; branches (from which the

needles have fallen) ver.y rough with peg-like structures ...... •••• 3. Picea 102

3. Leaves flat, blunt or acutish; branches not roughened •••• ...... • ••• 4. Pseudotsuga

1. Juniperus L. Juniper 1. Small trees or erect shrubs. • • 1. Juniperus scopulorum.

1. Low, spreading or creeping shrubs...... • • • • 2 2. Leaves mostly scale-like, opposite, appressed to

the stem, 1-1.5 mm long •••• 2. Juniperus horizontalis 2. Leaves awl-shaped, in whorls of 3, spreading, 5-10 mm long...... 3. Juniperus communis

1. Juniperus scopulorum Sarg. Open rocky places; southwestern

Alberta. Now known from gravel soil in riverbottom forest on Belly

River, 1.5 km southwest of Glenwood, Alberta. (Shaw 2360).

2. Juniperus horizontalis Moench. Commonon rocky and sandy

areas. St. Mary River at Cook's Ranch, Town Dam on Lee Creek, and

Highway 5 B~idge on Belly River. (Shaw 530, 1867, 604).

3. Juniperus communis L. W~de-ranging in open slopes and woods. East of Aetna on St. Mary River, Town Dam on Lee Creek, and

Highway 5 Bridge on Belly River. (Shaw 1307, 1831, 608).

2. Pinus L. Pine 1. Pinus flexilis James. Exposed rocky slopes and hill-tops

in southwest Alberta. Town Dam on Lee Creek. (Shaw 1057).

3. Picea Link Spruce

1. Picea glauca (Moench) Voss var. albertiana (S. Brown) Sarg. 103

Widespread in western Alberta. Occasional on St. Mary River, Belly

River and Lee Creek. (Shaw 570, 518).

4. Pseudotsuga Carr. Douglas-fir

1. Pseudotsuga menziesii (Mirb.) Franco. Rocky and gravelly sites in southwest Alberta. Sandstone banks on Lee Creek at Town Dam and The Narrows. (Shaw.1058).

CLASS2. ANGIOSPERMAE

SUBCLASS1. MONOCOTYLEDONEAE

5. TYPHACEAE- CATTAILFAMILY

1. Typha L. Cattail

1. Typha latifolia L. Marshes or shallow water; common in Alberta. St. Mary River at the mouth of Snake Creek. (Shaw 1941).

6. GRAMINEAE- GRASSFAMILY

Key to the Tribes

1. Spikelets with 2 staminate, neuter, or rudimentary lemmas

unlike and below the fertile lemma; no sterile or rudimentary floret above • • • • • • 1. Phalarideae

1. Spikelets without sterile lemmas below the perfect florets •• 2

2. Spikelets sessile or subsessile in spikes or spike-like racemes ...... • • . 3 2. Spikelets pedicellate in open or contracted, sometimes spike-like, panicles ...... • • • 4 I 3. Spikelets on opposite sides of the rachis; spike terminal and solitary . . . . . ••••.•••..••.• 2. Hordeae 104

3. Spikelets on one side of the rachis; spikes usually more than one, digitate or racemose ...... 3. Chlorideae 4. Spikelets I-flowered...... • •• 4. Agrostideae 4. Spikelets 2-many-flowered • • • • 5 5. Glumes as long as the lowest floret, usually as long as the spikelet; lemmas awned from the back . . . . • 5. Aveneae 5. Glumes shorter than the first floret; lemmas awnless

or awned from the tip or from a bifid apex 6. Festuceae

TRIBE 1. PHALARIDEAE

1. Phalaris L. Canary Grass

1. Phalaris arundinacea L. Shores and marshes throughout

Alberta. Snake Creek on St. Mary River. (Shaw 1938).

TRIBE 2. HORDEAE

1. Spikelets solitary at each node of the rachis • 1. Agropyron 1. Spikelets more than one at each node of the rachis 2. Elymus

1. Agropyron Gaertn. Wheat grass 1. Culms from creeping rhizomes ...... • • 2 1. Culms caespitose; creeping rhizomes absent or very short • 4

2. Glumes not rigid, mostly 6-9 mm long, lanceolate,

broader at the middle than at the base, the first

often 5-nerved; spikelets 3-8-flowered

1. Agropyron dasystachyum

2. Glumes rigid, 10-12 mm long, tapering from near the

base into a short awn, the first glume usually 105

1-3-nerved; spikelets 6-10-flowered •••••••••• 3

3. Lemmas glabrous or nearly so •••••••• 2. Agropyron smithii

3. Lemmas pubescent ••••••••••• 3. Agropyron smithii molle

4. Spikelets long-awned • • • 4. Agropyron subsecundum

4. Spikelets awnless or merely awn-tipped ••••••••••• 5

5. Glumes 2-2.5 mmwide, nearly as long as the spikelet;

rachilla villose; blades nea~ly flat

5. Agropyron trachycaulum

5. Glumes narrower, much shorter than the spikelet; rachilla

scaberulous; blades involute •••••• 6. Agropyron inerme

1. Agropyron dasystachyum (Hook.) Scribn. A wide-ranging species of prairie and other dry open places. Commonalong gravel flats of St. Mary River. (Shaw 2361).

2. Agropyron smithii Rydb. Commonin prairie grassland. Gravel flats on St. Mary River and Lee Creek. (Shaw 567, 1705).

3. Agropyron smithii Rydb. var. molle (Scribn. & Smith) Jones.

Commonin prairie grassland, especially on.heavier soils. East of

Aetna on St. Mary River. (Shaw 865).

4. Agropyron subsecundum (Link) Hitchc. Commonin parkland prairie and open woods of Alberta. St. Mary River at Cook's Ranch and Lee Creek at Town Dam. (Shaw 1014, 1738).

5. Agropyron trachycaulum (Link) Malte. Meadows and woodlands throughout Alberta. Riverbottom at Cook's Ranch on St. Mary River.

(Shaw 1034).

6. Agropyron inerme (Scribn. & Smith) Rydb. Throughout southern Alberta. St. Mary River at Cook's Ranch, East of Aetna 106

and Cardwell's Island. (Shaw 894, 1010, 970).

2. Elymus L. Wild-rye 1. Lemmas awn.less; spike 1-2.5 dm long, thick and dense

1. Elymus cinereus

1. Lemmas awned; spike usually shorter, slender or fairly

thick, often open or lax ••••••••• 2. Elymus glaucus

1. Elymus cinereus Scribn. & Merr. River banks, ravines, moist slopes; occasional in southern Alberta. River bank grassland associated with riverbottom forest, Cook's Ranch on St. Mary River.

(Shaw 1045).

2. Elymus glaucus Buckl. Woods and thickets. Commonin

southwestern Alberta. Cook's Ranch on St. Mary River. (Shaw 1026).

TRIBE 3. CHLORIDEAE

1. Spikelets with one perfect flower and 1 or more unlike

rudiments above; spikes comb-like, racemose along

the main axis. • • • • • • • • • • • • • • • 1. Bouteloua

1. Spikelets without additional modified florets • 2. Beckmannia

1. Bouteloua Lag. Grama Grass

1. Bouteloua gracilis (HBK.) Lag. Abundant in prairie grass-

land of southern Alberta. Occasionally in grassland adjacent to

riverbottom forest. Christensen Farm on St. Mary River. (Shaw 1643).

2. Beckmannia Host. Sloughgrass 107

1. Beckmannia syzigachne (Steud.) Fern. Marshes and ditches throughout Alberta. Muddy banks at mouth of Snake Creek, St. Mary River. (Shaw 1935).

TRIBE 4. AGROSTIDEAE

1. Fruit hardened, terete, awned, the nerves obscure; callus well developed, obliqu~, bearded...... • 2 1. Fruit thin or firm; callus not well developed • • • • 3

2. Awn persistent, twisted and bent, several to many times

as long as the fruit; callus sharp-pointed •••• 1. Stipa

2. Awn deciduous, not twisted, sometimes bent, rarely more than 3-4 times as long as the plump fruit;

callus short, usually obtuse ••••••••• 2. Oryzopsis

3. Glumes compressed-carinate; panicle dense, spike-like. 3. Phleum

3. Glumes not compressed-carinate; panicle not spike-like . . 4

4. Floret bearded at base; palea present .• 4. Calamagrostis 4. Floret not bearded, or only minutely hairy at base;

palea small or wanting •••••••• 5. Agrostis

1. Stipa L. Needlegrass

1. Stipa columbiana Macoun. Prairie grassland and open woods; western Alberta. Cardwell's Island on St. Mary River.

(Shaw 531).

2. Oryzopsis Michx. Ricegrass

1. Oryzopsis hymenoides (R. & S.) Ricker. Sand-dunes, dry banks, rocky slopes throughout Alberta. East of Aetna on St. Mary 108 River. (Shaw 714).

3. Phleum L. Timothy

1. Phleum pratense L. Meadows, roadsides, and along trails

in the mountains of Alberta. Highway 5 Bridge on Belly River.

(Shaw 1870).

4. Calamagrostis Adans. Reed Grass 1. Calamagrostis inexpansa A. Gray. Commonin marshy places and low meadows. Cardwell's Island on St. Mary River. (Shaw 1949).

5. Agrostis L. Bentgrass 1. Palea evident, at least half as long as the lemma,

2-nerved; often rhizomatous ••••••••• 1. Agrostis alba

1. Palea lacking, or minute and nerveless, not over

one-third as long as the lemma 2. Agrostis variabilis

1. Agrostis alba L. As an escape from cultivation, usually in damp places such as stream banks. Cook's Ranch on St. Mary River and Town Dam on Lee Creek. (Shaw 969, 1943).

2. Agrostis variabilis Rydb. Rocky places in the mountains.

Cook's Ranch on St. Mary River. (Shaw 1033).

TRIBE 5. AVENEAE

1. Lemma convex, awned from below the middle, truncate and

erose-dentate at sunnnit ••••••••• • 1. Deschampsia

1. Lennna keeled, the awn when present from above the 109 middle ...... 2. Koeleria

1. Deschampsia Beauv. Hairgrass

1. Culms 2-12 dm tall; basal leaves 1.5-4 mmwide; spikelets

3-5 mm long •••••••••••• 1. Deschampsia caespitosa

1. Culms less than 3 dm tall; basal leaves filiform, less

than 1.5 mmwide; spikelets less than 3 mm long

2. Deschampsia caespitosa glauca

1. Deschampsia caespitosa (L.) Beauv. A common species, often

prominent in wet places of prairie and mountain regions. Highway 5

Bridge on Belly River and Kimball Park on St. Mary River. (Shaw

1887, 2109).

2. Deschampsia caespitosa (L.) Beauv. var. glauca {Hartm.)

Sam. Belly River at Highway 5 Bridge. {Shaw 1889).

2. Koeleria Pers. Junegrass

1. Koeleria cristata (L.) Pers. Very_common in prairie grassland. East of Aetna on St. Mary River. (Shaw 862).

TRIBE 6. FESTUCEAE

1. Lemmas awned, the awn 1 mm or more long •• 1. Bromus

1. Lemmas awnless or awn-pointed, the point less than 1 mm long •• ...... • • 2 2. Spikelets in dense, rather 1-sided clusters towards the

ends of the panicle branches • • • • • 2. Dactylis 2. Spikelets not as above •••••• . . . . . • • • 3 110 3. Lemmas 8 mm long or more ...... 1. Bromus 3. Lemmas less than 8 mm long ...... 4 4. Lemmas with parallel nerves, these not converging towards the tip 3. Glyceria 4. Lemmas with nerves converging towards the tip,

compressed-keeled or rounded on the back •••••• 4. Poa

1. Bromus L. Bromegrass

1. Weedy annual; mostly rather small slender plants with pubescent sheaths and blades . . . 1. Bromus tectorum 1. Perennials; relatively large grasses, pubescent or

glabrous • • • • • • 2

2. Creeping rhizomes present; panicle with ascending branches; lemmas glabrous . . . . . 2. Bromus inermis 2. Creeping rhizomes absent; panicle with spreading or

drooping branches; lemmas hairy along the

margin. ••••••••••• 3. Bromus ciliatus

1. Bromus tectorum L. Locally abundant on roadsides and waste places, especially in southwestern Alberta. East of Aetna on

St. Mary River. (Shaw 696).

2. Bromus inermis Leyss. Introduced for hay and pasture; persisting as a weed. East of Aetna on St. Mary River, Slaughter Hole on Lee Creek and Highway 5 Bridge on Belly River. (Shaw 710, 1707,

1851).

3.· Bromus ciliatus L. Commonin open woods and clearings.

Highway 5 Bridge on Belly River. (Shaw 1841). 111

2. Dactylis L. Orchard Grass

1. Dactylis glomerata L. Occasionally found as an escape

from cultivation. Cook's Ranch on St. Mary River. (Shaw 1025).

3. Glyceria R. Br. Manna Grass

1. Panicles narrow, erect; spikelets linear, nearly terete, over 7 mm long ••••••••••••• 1. Glyceria borealis

1. Panicles usually broad, open, nodding; spikelets ovate

or oblong, somewhat flattened, 2-7 mm long

2. Glyceria grandis

I. Glyceria borealis (Nash) Batchelder. Shallow water and wet meadows. Muddy banks at mouth of Snake Creek, St. Mary River. (Shaw 1942). 2. Glyceria grandis S. Wats. Common·in marshy places. Wet sandy area at Town Dam on Lee Creek. (Shaw 1734).

4. Poa L. Bluegrass

1. Creeping rhizomes present • 2

1. Creeping rhizomes lacking. • • 3 2. Culms conspicuously flattened ••• 1. Poa compressa

2. Culms terete or slightly flattened. • •• 2. Poa pratensis

3. Lemmas webbed at base (a cluster of long crinkly hairs)

3. Poa interior

3. Lemmas not webbed at base ••••••• 4. Poa cusickii

1. Poa compressa L. Introduced grass of meadows and wet 112 places. East of Aetna on St. Mary River. (Shaw 635).

2. pratensis L. Introduced leading grass of meadows and lawns. East of Aetna on St. Mary River and Slaughter Hole on Lee

Creek. (Shaw 893, 1704). 3. Poa interior Rydb. Widespread and common in parkland prairies. Cardwell's Island on St. Mary River. (Shaw 973).

4. Poa cusickii Vasey. Prairie region and dry mountain slopes. East of Aetna on St. Mary River. (Shaw 701).

7. CYPERACEAE-SEDGE FAMILY

1. Flowers imperfect; plants monoecious or dioecious •••• 1. Carex

1. Flowers all perfect, or at least one in each

spikelet perfect ••••••••••••• • • • • 2 2. Achenes crowned with a tibercle 2. Eleocharis

2. Achenes without a persistent tubercle 3. Scirpus

1. Carex (Rupp.) L. Sedge

1. Carex flava L. Banks and wet meadows. Highway 5 Bridge on Belly River. (Shaw 1891).

2. Eleocharis R. Br. Spikerusb

1. Eleocharis palustris (L.) R. & S. Very common in wet places. Mouth of Snake Creek on St. Mary River. (Shaw 1944).

3. Scirpus L. Bullrush

1. Involucral bract solitary, not leaf-like; cauline leaves usually much reduced ...... 1. Scirpus acutus 113 1. Involucral bracts 2 or more, leaf-like; cauline leaves

usually well developed ••••••••• 2. Scirpus paludosus

1. Scirpus acutus Muhl. Marshes and shores. Mouth of Snake

Creek on St. Mary River. (Shaw 1946).

2. Scirpus paludosus A. Nels. Low wet ground, especially saline flats. Rather common in the prairie region. Seepage channel in riverbottom forest, East of Aetna on St. Mary River. (Shaw 883).

8. JUNCACEAE-RUSH FAMILY

1. Juncus L. Rush 1. Leaves neither septate nor nodulose . . . . 1. Juncus longistylis 1. Leaves septate or nodulose, rather thick and spongy •••••• 2

2. Inflorescence with short branches; heads appearing

prickly with the spreading flowers; capsules

narrowly lanceolate 2. Juncus torreyi

2. Inflorescence with elongated branches; flowers erect-ascending; capsules oblong or broadly

lanceolate ••••••••••••••• 3. Juncus alpinus

1. Juncus longistylis Torr. Moist meadows and shores. Wet sandy drainage channels, East of Aetna on St. Mary River and Town Dam on Lee Creek. (Shaw 872, 1747).

2. Juncus torreyi Coville. Wet ground; occasional in the prairie region. Wet muddy bank, Highway 5 Bridge on Belly River.

(Shaw 1882).

3. Juncus alpinus Vill. var. rariflorus Hartm. Wet meadows 114 and shores. Town Dam on Lee Creek. (Sha~ 1745).

9. ALISMACEAE-WATER-PLANTAIN FAMILY

1. Sagittaria L. Arrowhead 1. Sagittaria cuneata Sheld. In mud and shallow water throughout Alberta. Mud banks at mouth of Snake Creek on St. Mary River. (Shaw 1933).

10. LILIACEAE - LILY FAMILY

1. Leaves linear or linear-lanceolate, usually many times longer

than wide; fruit dry • • • • • • • • • • • • • • • • • 2

1. Leaves lanceolate or broader, not more than 5 times as long

as wide; fruit often juicy •••• • • 4

2. Flowers 1-3 (rarely as many as 3) ...• 1. Lillium 2. Flowers more than 3, often very numerous...... • • 3 3. Flowers in umbels; plants with onion odor. 2. Allium 3. Flowers in dense or slender racemes. • • 3. Zygadenus

4. Flowers one to each stem 4. Fritillaria

4. Flowers several or numerous on each stem • • • 5

5. Flowers in racemes or panicles at the ends of the stems,

white; stems not branched. • • ••••••• 5. Smilacina

5. Flowers 1-4 at the ends of the branches, or solitary or clustered in the leaf-axils; stems nearly always branched ...... 6. Disporum

1. Lilium L. Lily

1. Lilium philadelphicum L. var. andinum (Nutt.) Ker. 115

Prairies and open woods. East of Aetna and Cardwell's Island on St.

Mary River. (Shaw 875, 954).

2. Alliunt L. Onion

1. Leaves terete or nearly so, hollow at least towards the

base; inflorescence subcapitate. 1. Allium schoenoprasum 1. Leaves flat or channeled, not hollow; inflorescence umbellate ...... • 2 2. Outer bulb coats without fibers, or with parallel fibers,

not fibrous-reticulate; umbel nodding

2. Allium cernuum

2. Outer bulb coats fibrous-reticulate; umbel erect

or nearly so 3. Allium textile

1. Allium schoenoprasum L. var. sibiricum (L.) Hartm. Wet meadows, banks and shores. Cook's Ranch on St. Mary River and

Slaughter Hole on Lee Creek. (Shaw 746, 1890). 2. Allium cernuum Roth. Parkland prairies, open slopes, thickets, rock slides. East of Aetna on St. Mary River, Slaughter

Hole on Lee Creek and Highway 5 Bridge on Belly River. (Shaw 1006,

1685, 1884). 3. Allium textile Nels. & Macbr. Commonon dry plains and hills. East of Aetna on St. Mary River, Cardston on Lee Creek, and

Standoff on Belly River. (Shaw 631,.655, 469).

3. zxgadenus·Michx. Death Camas

1. Zygadenus gramineus Rydb. Connnonin southern Alberta. 116 Cook's Ranch on St. Mary River. (Shaw 774).

4. Fritillaria L. Yellow Bells

1. Fritillaria pudica (Pursh) Spreng. Mountain and foothill slopes; southwestern Alberta. Woolford Park on St. Mary River and

Town Dam on Lee Creek. (Shaw 1229).

5. Smilacina Desf. False Solomon's Seal 1. Flowers in a panicle; large plant . . 1. Smilacina racemosa 1. Flowers in a raceme. . . 2. Smilacina stellata

1. Smilacina racemosa (L.) Desf. var. amplexicaulis (Nutt.)

S. Wats. Damp woods and thickets. Cook's Ranch on St. Mary River,

Slaughter Hole on Lee Creek, and Highway 5 Bridge on Belly River.

(Shaw 737, 1484, 512).

2. Smilacina stellata (L.) Desf. Moist shores, open woods and prairies. Woolford Park on St. Mary River, Town Dam on Lee Creek and Standoff on Belly River. (Shaw 552, 1265, 465).

6. Disporum Salisb. Fairy Bells 1. Disporum oreganum (A. Wats.) B. & H. Moist woods in southwestern Alberta. Town Dam on Lee Creek and Highway 5 Bridge on Belly

River. (Shaw 517, 1259).

11. IRIDACEAE- IRIS FAMILY

1. Sisyrinchium L.

1. Sisyrinchium montanum Greene. Low meadows. Grassland 117 associated with riverbottom forest at Woolford Park on St. Mary River. (Shaw S33).

12. ORCHIDACEAE- ORCHID FAMILY 1. Plants saprophytic, with reduced non-green leaves;

rhizome coralloid •••••••••••••• 1. Corallorhiza 1. Plants not saprophytic; leaves with well developed blades ...... • • • • 2 2. Flower 1 on a naked scape; leaf solitary, basal 2. Calypso

2. Flowers 2-many, in racemes or spikes •••••• 3. Habenaria

l. Corallorhiza (Hall.) Chat. Coral-root

1. Corallorhiza striata Lindl. Woods in southern Alberta.

Deep woods at Slaughter Hole on Lee Creek. (Shaw 1448).

2. Calypso Salish. Venus'-slipper

1. Calypso bulbosa (L.) Oakes. Coniferous forests; western and northern Alberta; Cypress Hills. Now known from gravel soil in deciduous riverbottom forest at Kimball Park on St. Mary River,

Kimball, Alberta. Known from two plants positively identified but uncollected because of the. rarity of the species, June of 1967.

3. Habenaria Willd. Bog Orchid

1. Lip 2-3-toothed, oblong; spur pouch-like, 2-3 mm long,

almost concealed 1. Habenaria viridis

1. Lip entire, variously shaped 2. Habenaria hyperborea 118

1. Habenaria viridis (L.) R. Br. var. bracteata (Muhl.)

A. Gray. Moist meadows and woods. Damp soil, East of Aetna on St.

Mary River, Slaughter Hole on Lee Creek, and Highway 5 Bridge on

Belly River. (Sha,1 879, 1445, 1833). 2. Habenaria hyperborea (L.) R. Br. Bogs, wet meadows and woods. Highway 5 Bridge on Belly River. (Shaw 1833a).

13. URTICACEAE-NETTLE FAMILY

1. Urtica lyallii S. Wats. Low ground in the mountains; southwestern Alberta. Now known from loam soil in riverbottom forest

- fescue grassland transition, Cook's Ranch on St. Mary River, 3 km north of the International Boundary, Alberta. (Shaw 1043).

14. SALICACEAE-WILLOW FAMILY

1. Winter buds covered by several scales; catkins soon drooping;

bracts of catkins mostly lacerate; flowers with a broad

or cup-shaped disk; stamens usually more than 10; trees 1. Populus

1. Winter buds covered by a single scale; catkins erect or

divergent, rarely drooping; bracts entire or merely

toothed; disk none; stamens few, often 2; mostly shrubs ...... • 2. Salix

1. Populus L. Cottonwood, Poplar

1. Petioles strongly flattened laterally ...... • • • • • 2 1. Petioles circular or semi-circular in cross-section, not flattened ...... • • • • • 3 119 2. Leaf blades small, suborbicular, crenulate or nearly

entire; bark of trunk (well above base) smoothish,

light green to whitish ••••••• 1. Populus tremuloides

2. Leaf blades large, broadly deltoid to cordate, coarsely toothed, often crenate; bark of trunk deeply

furrowed, usually gray ••••• 2. Populus sargentii 3. Petioles one-third the length of the blade or shorter;

blades 3-7 times as long as broad, gradually

tapered to the apex 3. Populus angustifolia

3. Petioles longer and blades broader than above...... 4

4. Blades green on both sides, abruptly acuminate, rhombic-

lanceolate to ovate •• 4. Populus X acuminata

4. Blades paler beneath, acute or somewhat acWllinate,

not at all rhombic •••• • • 5

5. Blade olive-green above, slightly glaucous, slightly brown

resinous, blade width-to-length ratio 0.4-0.6 and

base to widest point-to-length ratio 0.33-0.4,

2-year old twigs ivory-gray

5. Populus angustifolia X balsamifera

5. Blade green above, strongly flaucous, decidedly brown

resinous, blade width-to-length ratio over 0.6 and

base to widest point-to-length ratio 0.33; 2-year

old twigs dull gray

6. Populus balsamifera subsp. trichocarpa

1. Populus tremuloides Michx. Very common throughout the forested ragions and parklands. Scattered along the river valleys: 120

Cardwell's Island on St. Mary River, Town Dam on Lee Creek, and

Standoff on Belly River. (Shaw 848, 815).

2. Populus sargentii Dode

= P. deltoides Marsh var. occidentalis Rydb. River banks

and moist sand-dunes; southern Alberta. Lee Creek at Cardston and

Belly River at Monarch. (Shaw 1190, 482). (The Cardston specimen is

probably P. sargentii X angustifolia).

3. Populus angustifolia James. Commonin stream valleys of

southern Alberta. Cardwell's Island on St. Mary River, Slaughter

Hole on Lee Creek, and Standoff on Belly River. (Shaw 942, 1184,

462).

4. Populus X acuminata Rydb. River valleys of southern

Alberta. Lee Creek at Cardston and St. Mary River at Christensen

Farm. (Shaw 484, 1324).

5. Populus angustifolia James X balsamifera L. Common

throughout the riverbottom forest of southern Alberta where the

ranges of the parent species overlap. St. Mary River at Cardwell's

Island, Lee Creek at Slaughter Hole, and Belly River at Standoff.

(Shaw 939, 1192).

6. Populus balsarnifera L. subsp. trichocarpa (T. & G.) Brayshaw. Commonin forested regions throughout southern Alberta.

Cook's Ranch on St. Mary River, Slaughter Hole on Lee Creek, and

Standoff on Belly River. (Shaw 577, 1204, 822).

2. Salix L. Willow

1. Trees, having one main trunk at base, usually 1 dm in

diameter or larger; 3-12 m tall •••• 1. Salix amygdaloides 121 1. Shrubs, with multiple stems ...... • • • 2 2. Leaves linear, 6 or more times as long as broad, less than 1 cm wide ...... • 3 2. Leaves less than 6 times as long as broad • 4

3~ Mature leaves gray-puberulent on both surfaces, entire

or remotely denticulate. 2. Salix exigua

3. Mature leaves glabrous or nearly so on both sides,

denticulate or subentire 3. Salix interior 4. Mature leaves glabrous •••• . . . . . • s 4. Mature leaves hairy (lens needed) 11

S. Leaf margins entire •• • 6 S. Leaf margins toothed or at least partly toothed. . . • • • 7 6. Shrubs 2-10 m tall; leaves dull green above 4. Salix bebbiana

6. Shrubs less than 1 m tall; branchlets bright

red 5. Salix farrae

7. Leaves usually with 2 or more glands or processes at base

of blade on upper surface, leaves gradually tapered to

tip, 3-5 times longer than wide. • 8 7. Leaves without prominant glands •• . . . • • 9 8. Leaves short-acuminate, glaucous beneath; pedicels

about 2 mm long •••••• 6. Salix lasiandra

8. Leaves long-acuminate, scarcely paler beneath;

pedicels about 1-1.5 mm long ••••••• 7. Salix caudata

9. Leaf blades mostly widest well above the middle and I abruptly tapering to tip . . . . . ••• 8. Salix scouleriana 9. Leaf blades widest at about the middle; branchlets 122 finely hairy ...... 10 10. Capsule (if present) glabrous; leaves lanceolate,

shallowly serrulate to entire, yellowish green;

stipules absent •••••••••••••• 9. Salix lutea

10. Capsule (if present) hairy; leaves linear-lanceolate

or narrowly oblanceolate, entire or sharply

serrulate, lustrous green and glabrous above,

glaucous and glabrous beneath 10. Salix petiolaris 11. Leaves permanently densely white hairy beneath; green

and sparingly hairy or glabrous above •• 8. Salix scouleriana

11. Leaves either white woolly-hairy on both surfaces or

sparingly hairy on one or both surfaces •••• 12

12. Leaves toothed, glaucous beneath, not tomentose on both sides...... 4. Salix bebbiana 12. Leaves entire, glaucous or pale green beneath •••••• 13

13. Leaves broader toward tip than middle ••• 8. Salix scouleriana

13. Leaves generally widest toward middle 4. Salix bebbiana

1. Salix amygdaloides Anderss. Along streams in southern

Alberta. East of Aetna on St. Mary River, Highway 5 Bridge on Belly

River. (Shaw 867, 1052).

2. Salix exigua Nutt. Along streams, ditches and other wet places in southern Alberta. Woolford Park on St. Mary River. (Shaw

526).

3. Salix interior Rowlee. Moist alluvial soil and sand bars.

Comm.onalong streams and ditches. Cardwell's Island on St. Mary

River and Town Dam on Lee Creek. (Shaw 938, 1164). 123

4. Salix bebbiana Sarg. Woods, thickets, borders of sloughs; very common. Cardwell's Island on St. Mary River. (Shaw 855).

5. Salix farrae Ball. Bogs and wet mountain meadows; Rocky

Mountains, southwestern Alberta. Now known from riverbottom forest on Cardwell's Island, St. Mary River, 7 km southeast of Cardston, Alberta. (Shaw 851). . 6. Salix lasiandra Benth. Stream banks and moist valley slopes. Cook's Ranch on St. Mary River. (Shaw 575).

7. Salix caudata (Nutt.) Heller. Wet places; southwestern

Alberta and Cypress Hills. Woolford Park on St. Mary River. (Shaw

1151). 8. Salix scouleriana Barrat. Hillsides and along streams; western and northern Alberta and Cypress Hills. Cook's Ranch on St.

Mary River and Highway 5 Bridge on Belly River. (Shaw 509, 576).

9. Salix lutea Nutt. Commonon river banks, along ditches and in other wet places. Kimball Park on St. Mary River and Standoff on Belly River. (Shaw 1272, 1216).

10. Salix petiolaris J.E. Sm. Moist meadows, banks and shores. Cardwell's Island on St. Mary River. (Shaw 523).

15. BETULACEAE-BIRCH FAMILY

1. Betula L. Birch 1. Betula occidentalis Hook. Along streams and in other wet places; common in southern Alberta. Cook's Ranch on St. Mary River and Slaughter Hole on Lee Creek. (Shaw 574, 1203).

16. RANUNCULACEAE-BUTTERCUP FAMILY 124 1. Carpels with several ovules; fruit a berry ...... 1. Actaea 1. Carpels 1-ovuled, ripening into achenes ••• • • 2

2. Petals usually present, yellow or whitish 2. Ranunculus

2. Petals lacking; sepals often petal-like • • • • 3

3. Stem leaves forming a pronounced involucre; basal leaves

simple, long-petioled •••• 3. Anemone

3. Stem leaves not forming a pronounced involucre, compound ...... 4 4. Leaves alternate, large and ternately compound;

herbs; mostly dioecious 4. Thalictrum

4. Leaves opposite, with 3-7 leaflets; climbing

shrubs • • • 5. Clematis

1. Actaea L. Baneberry

1. Berries red. 1. Actaea rubra 1. Berries white...... 2. Actaea rubra neglecta

1. Actaea rubra (Ait.) Willd. Commonin forest through the region. Coalmine Coulee on St. Mary River, Slaughter Hole on Lee

Creek, and Highway 5 Bridge on Belly River. (Shaw 1420, 1446, 1844).

2. Actaea rubra (Ait.) Willd. forma neglecta (Gillman) Robins.

Highway 5 Bridge on Belly River. (Shaw 1845).

2. Ranunculus (Tourn.) L. Buttercup

1. Leaves entire or merely toothed; plants with stolons I or runners . • ...... 1. Ranunculus cymbalaria 1. Leaves all, or in part, deeply lobed to compound ...... 2 12S

2. Terminal segment of the larger leaves stalked; stem.

creeping, rarely erect •••••••• 2. Ranunculus repens

2. Terminal segment of the larger leaves sessile, usually

joined with the lateral by thin tissue, or the leaves digitately divided and incised . . . . . • • • • 3 3. Achenes plump, without wing-like margins; basal leaves

ternately divided to digitately cleft

3. Ranunculus oedatifidus 3. Achenes flattened with distinct margins; basal leaves

palmately 3-5-lobed ••••••••••• 4. Ranunculus acris

1. Ranunculus cymbalaria Pursh. Wet saline areas, border of

ponds and lakes, stream banks; common. Muddy banks east of Aetna and

Coalmine Coulee on St. Mary River. (Shaw 871, 1433). 2. Ranunculus repens L. Native of Europe; expected in

Alberta, but no plants seen. Now known from mud banks of St. Mary

River, 7 km southeast of Cardston, Alberta. (Shaw 1948).

3. Ranunculus pedatifidus J.E. Smith var. affinis (R. Br.)

L. Benson. Meadows in the mountains and elsewhere. Belly River at

Monarch. (Shaw 485).

4. Ranunculus acris L. Commonweed in our region, generally

on roadsides, damp meadows and clearings. East of Aetna on St. Mary

River, Slaughter Hole on Lee Creek, and Hillspring Park on Belly

River. (Shaw 703, 1435, 837).

3. Anemone-L. Pasque Flower

1. Anemone multifida Poir. Very common in prairie grassland 126

and dry open woods. Woolford Park on St. Mary River and Slaughter

Hole on Lee Creek. (Shaw 534, 1715).

4. Thalictrum L. Meadow-rue

1. Thalictrum venulosum. Trel. Woods, thickets and moist

places in prairie; very connnon. Highway 5 Bridge on Belly River. (Shaw 1837).

5. Clematis L. Virgin's Bower

1. Flowers white and clustered, unisexual; leaflets 5 or 7,

toothed •••••••••••••• 1. Clematis ligusticifolia

1. Flowers purple, large, borne singly, perfect;

leaflets 3, entire 2. Clematis verticellaris

1. Clematis ligusticifolia Nutt. Commonin coulees and river valleys of southern Alberta. Slaughter Hole on Lee Creek. (Shaw 1208).

2. Clematis verticellaris DC. var. columbiana (Nutt.) A. Gray.

Thickets and woods, widely distributed but sporadic in Alberta. East

of Cardston on St. Mary River, Town Dam on Lee Creek, and Highway 5

Bridge on Belly River. (Shaw 681, 1267, 514).

17. CARYOPHYLLACEAE-PINK FAMILY 1. Petals entire or emarginate ••• . . . 1. Arenaria 1. Petals deeply notched or 2-cleft . . . . . • 2. Cerastium

1. Arenaria L. Sandwort 127

1. Arenaria lateriflora Poir. Moist meadows, gravelly shores, thickets and woods. Coalmine Coulee on St. Mary River. (Shaw 1417).

2. Cerastium L. Mouse-ear Chickweed 1. Cerastium arvense L. Dry ground of plains, hills and mountains; common in prairie parkland. Woolford Park on St. Mary

River. (Shaw 547).

18. POLYGONACEAE-BUCKWHEAT FAMILY

1. Leaves without stipules; flowers in small clusters, each

cluster surrounded by a toothed or lobed involucre;

stamens 9 ••• • • • • • • • • • 1. Eriogonum:

1. Leaves with ocreae; flowers not in involucrate clusters;

stamens 8 or fewer 2. Rumex

1. Eriogonum Michx. Umbrella-plant

1. Eriogonum flavum Nutt. Dry exposed places; connnon in southern Alberta. Cook's Ranch on St. Mary River and Highway 5

Bridge on Belly River. (Shaw 794, 1780).

2. Rumex L. Sorrel

1. Leaves crisped on the margins; plants without axillary

shoots; tubercles plump, nearly globose. 1. Rumex crispus

1. Leaves not crisped on margins; plants often with

axillary shoots; tubercles half as wide as long

or narrower •••••• ••• •• 2. Rumex mexicanus 128 1. Rumex crispus L. Introduced weed of moist ground; not common. Town Dam on Lee Creek. (Shaw 1746).

2. Rumex mexicanus Meisn. Commonin wet open ground or thickets. Cardwell's Island on St. Mary River. (Shaw 1940).

19. ACERACEAE-MAPLE FAMILY

1. L. Maple

1. Acer negundo L. var. interius (Britt.) Sarg. Along streams of southern Alberta as an escape from cultivation. Slaughter Hole on Lee Creek. (Shaw 2192).

20. EUPHORBIACEAE-SPURGE F.AMILY

1. Euphorbia L. Spurge

1. Euphorbia esula L. A noxious weed, firmly established in several fields, roadsides and river flats of Alberta. Woolford Park on St. Mary River and Cardston on Lee Creek. (Shaw 549, 662).

21. ELAEAGNACEAE-OLEASTER FAMILY 1. Leaves alternate; stamens 4 ...... ••• 1. Elaeagnus 1. Leaves opposite; stamens 8 . . . . 2. Shepherdia

1. Elaeagnus L. Oleaster 1. Elaeagnus commutata Bernh. Commonon lighter soils of parkland regions and valley slopes. Cardwell's Island on St. Mary

River, Slaughter Hole on Lee Creek, and Standoff on Belly River.

(Shaw 945, 1209, 479). 129

2. Shepherdia Nutt. Buffalo-berry

1. Leaves silvery on both sides; plants thorny

1. Shepherdia argentea

1. Leaves green and nearly glabrous above, silvery and brown-scurfy beneath; plants unarmed

2. Shepherdia canadensis

1. Shepherdia argentea Nutt. Coulees and river valleys of southern Alberta. Woolford Park on St. Mary River, Slaughter Hole on

Lee Creek, and Standoff on Belly River. (Shaw 1225, 1202, 464).

2. Shepherdia canadensis (L.) Nutt. Slopes and thin woods, throughout forested regions of Alberta. East of Cardston on St. Mary

River and Highway 5 Bridge on Belly River. (Shaw 683, 511).

22. SANTALACEAE-SANDALWOOD FAMILY 1. Comandra Nutt.

L Comandra pallida A. DC. Prairie grassland, gravelly slopes and dry open pine woods. East of Aetna on St. Mary River and

Standoff on Belly River. (Shaw 647, 463).

23. MALVACEAE-MALLOW FAMILY

1. Sphaeralcea St. Hil. Scarlet Mallow

1. Sphaeralcea coccinea (Pursh) Rydb. Commonon prairie grassland. The Narrows on Lee Creek. (Shaw 1061).

24. ROSACEAE-ROSE FAMILY

1. Herbs, or with a woody base and otherwise herbaceous ••••• 2 130 1. Shrubs or trees ••• ...... • . . . s 2. Stamens 5; carpels 5-20; petals small, little if any longer than the sepals ...... 1. Chamaerhodos 2. Stamens 10 or more; carpels 10-many; petals usually longer than the sepals ...... 3 3. Basal leaves with more than 3 leaflets 2. Potentilla 3. Basal leaves with only 3 leaflets •• . . . . . • • • • 4 4. Petals white; plants with stolons; receptacle fleshy

in fruit (strawberry type) • 3. Fragaria 4. Petals yellow; fruit dry ...... 2. Potentilla 5. Ovary or ovaries superior; hypanthium shaped like a saucer, cup or urn and free from the ovary; fruit

not a pome •••••••• • • • • • 6

5. Ovary (compound) inferior, enclosed in and adnate to the hypanthium; fruit a pome but often berry-like. . . . 10 6. Carpel l; fruit a drupe; leaves simple •••• 4. Prunus

6. Carpels 2 or more; leaves simple or compound • • 7

7. Leaves simple. •• 5. Rubus

7. Leaves compound •• • 8

8. Fruit fleshy; bractlets none in flower. . . 9

8. Fruit dry (achenes); bractlets alternating with the sepals ••• . . . . 2. Potentilla 9. Carpels becoming drupelets (raspberry type) • • 5. Rubus

9. Carpels becoming achenes, enclosed in a fleshy receptacle ...... 6. Rosa I 10. Leaves mostly incised-toothed or lobed; stems with stout spines ...... • ...... 7. Crataegus 131 10. Leaves entire to toothed; stems not thorny •• 8. Amelanchier

1. Chamaerhodos Bunge

1. Chamaerhodos erecta (L.) Bunge ssp. nuttallii (Pickering)

Hulten. Dry sopes and plains; often on sandy or gravelly soils.

East of Aetna on St. Mary River. (Shaw 860).

2. Potentilla L. Cinquefoil

1. Shrub; flowers yellow; leaves pinnate 1. Potentilla fruticosa

1. Herbs (or, merely woody at the base) • • • • 2

2. Flowers solitary on naked peduncles, mostly from the

nodes of stolons; leaves pinnate, with many

leaflets. 2. Potentilla anserina

2. Flowers few to many, cymose, if solitary the plant

dwarf and caespitose •••••• • 3

3. Principal leaves digitately 5-9-foliolate. • • • 4 3. Principal leaves pinnate ...... • • 5 4. Lower surface of leaf without tomentum, often hirsute

or pilose • 3. Potentilla gracilis

4. Lower surface of leaf densely white or gray tomentose;

depressed, spreading plants • 4. Potentilla concinna 5. Leaflets green above, very close together; leaf

nearly digitate. 3. Potentilla gracilis

5. Leaflets whitish to silvery-gray above leaf

distinctly pinnate 5. Potentilla hippiana

1. Potentilla fruticosa L. Foothills prairie region of 132 southern Alberta; open areas in the Rocky Mountains; boggy thickets of northern Alberta. Woolford Park on St. Mary River, Slaughter Hole on Lee Creek, and Highway 5 Bridge on Belly River. (Shaw 520, 1694, 1868).

2. Potentilla anserina L. Low meadows, lake-shores, stream- banks. Woolford Park on St. Mary River. (Shaw 525).

3. Potentilla gracilis Dougl.

= !_. nuttallii Lehm. Commonon prairie grassland. Cook's

Ranch on St. Mary River and Highway 5 Bridge on Belly River. (Shaw

1040, 1853).

4. Potentilla concinna Richards. Dry prairies and hills; common in southern Alberta. Woolford Park on St. Mary River. (Shaw

1231).

5. Potentilla hippiana Lehm. Commonspecies of prairies and mountain slopes in southern Alberta. Cook's Ranch on St. Mary River.

(Shaw 756).

3. Fragaria L. Strawberry

1. Leaflets narrowly obovate, elliptic or oblong-cuneate,

usually glaucous above; pubescence of petioles and scapes commonly appressed or ascending; petals

usually exceeding the sepals by about half

1. Fragaria virginiana glauca

1. Leaflets broadly ovate or cuneate, not usually so

markedly glaucous; pubescence of petioles and

scapes spreading or somewhat reflexed; petals

broad and usually twice as long as the sepals 133

2. Fragaria virginiana platypetala

1. Fragaria virginiana Duchesne var. glauca S. Wats. Wide

ranging in moist forests and dry prairie grassland. East of Aetna on

St. Mary River, Town Dam on Lee Creek, and Standoff on Belly River.

(Shaw 1235, 1257, 467).

2. Fragaria virginiana Duchesne var. platypetala (Rydb.) Hall.

Alpine areas; southwestern Alberta. Now known from riverbottom

forest on St. }fary River, 0.5 km upstream from Woolford Park, 1.5 1an southwest of Woolford, Alberta. (Shaw 538).

4. Prunus L. Cherry, Plum

1. Leaf margin sharply serrate, teeth not glandular;

branching alternate; stems not spinescent

1. Prunus virginiana melanocarpa

1. Leaf margins with rounded teeth, each tooth ending in a

large gland; branching tending to be opposite; stems spines cent ...... 2. Prunus nigra

1. Prunus virginiana L. var. melanocarpa (A. Nels.) Sarg.

Thickets and open woods; c9mmon. Woolford Park on St. Mary River,

Town Dam on Lee Creek, and Highway 5 Bridge on Belly River. (Shaw

521, 1162, 1832).

2. Prunus nigra Ait. Previously unreported from Alberta.

Now known from a small population on Lee Creek, 0.5 km southwest of

Cardston, Alberta. (Shaw 1218). 134

5. Rubus L. Raspberry

1. Rubus strigosus Michx. Widespread and prevalent in

forested parts of Alberta. Town Dam on Lee Creek.

6. Rosa L. Rose

1. Leaflets oval to obovate, mostly 1-3 cm long, regularly

serrate, the teeth often ac~inate; stems with

scattered bristles or bristly at the base only;

thorns commonly present at the base of the stipules; leaflets usually 5-9 ...... 1. Rosa woodsii 1. Leaflets oblong-elliptic, often 3-4 cm long, irregularly

dentate-serrate, the teeth acute; stems bristly to

tips; thorns directly·below the stipules none or

not different from the internodal ones; leaflets

commonly 5-7 ••••••••••••••• 2. Rosa acicularis

1. Rosa woodsii Lindl. Prairies, woods, ravines, sandhills;

the most widespread and prevalent rose in Alberta. East of Aetna on

St. Mary River, Town Dam on Lee Creek, and Highway 5 Bridge on Belly

River. (Shaw 573, 1161, 1846).

2. Rosa acicularis Lindl. Woods. banks, roadsides; common,

especially in forested regions. Cook's Ranch on St. Mary River and

Slaughter Hole on Lee Creek. (Shaw 795, 1207).

7. Crataegus L. Hawthorn

1. Crataegus chrysocarpa Ashe. Slopes of coulees and river valleys; open woods; common. East of Aetna on St. Mary River and 135

Slaughter Hole on Lee Creek. (Shaw 649, 1201).

8. Amelanchier Medic. Service-berry

1. Amelanchier alnifolia Nutt. Very common in open woodlands.

Cook's Ranch on St. Mary River, Town Dam on Lee Creek, and Highway 5

Bridge on Belly River. (Shaw 736, 1166, 1860).

25. CAPPARIDACEAE-CAPER FAMILY

1. Cleome L. 1. Cleome serrulata Pursh. Waste places, roadsides and disturbed prairie areas; southern Alberta. Slaughter Hole on Lee

Creek. (Shaw 1998).

26. LOASACEAE- LOASA FAMILY

1. Mentzelia L. Blazing Star

1. Mentzelia decapetala (Pursh) Urban & Gilg. Dry eroded hillsides and banks; southern Alberta. Cardwell's Island on St. Mary

River. (Shaw 1133).

27. PRnrutACEAE- PRIMROSEFAMILY

1. Leaves all or chiefly cauline; flowers rarely in definite

umbels • • • • • • • • • • • • 1. Lysimachia

1. Leaves in a basal rosette or clustered at the ends of

short branches of the caudex; flowers commonly in

terminal umbels • 2. Androsace

1. Lysimachia L. Loosestrife 136

1. Lysimachia ciliata L. Moist thickets, woods and shores.

Woolford Park on St. Mary River, Slaughter Hole on Lee Creek, and

Highway 5 Bridge on Belly River. (Shaw 974, 1700, 1892).

2. Androsace L. 1. Androsace septentrionalis L. var. subumbellata A. Nels.

Very common on the prairie and in dry open places elsewhere. East of

Aetna on St. Mary River. (Shaw 1236).

28. GERANIACEAE-GERANIUM FAMILY

1. Geranium L. Geranium

1. Petals white or purple-tinged, pilose on the inner

surface one-third to one-half their length; pedicels

in pairs, commonly glandular-hairy, the glands

purplish, occasionally non-glandular

1. Geranium richardsonii

1. Petals purple to pink, rarely white, pilose inside not

one-fourth their length; pedicels often in 3's or

4's, sometimes in pairs, if glandular-hairy not

purplish ••••••••••••• 2. Geranium viscosissimum

1. Geranium richardsonii Fisch. & Trautv. Moist thickets and open woods; widespread in forested regions. Highway 5 Bridge on Belly

River. (Shaw 1859).

2. Geranium viscosissimum Fisch. & Mey. Moist places in fescue grassland and in thickets; southern Alberta. Coalmine Coulee on St. Mary River. (Shaw 1419). 137

29. CRASSULACEAE-ORPINE FAMILY I. Sedum L. Stonecrop

I. Sedum stenopetalum Pursh. Slopes and ridges; common in western Alberta. Cook's Ranch on St. Mary River. (Shaw 742).

30. SAXIFRAGACEAE-SAXIFRAGE FAMILY 1. Shrubs . . . . ••• 1. Ribes I. Herbs •• ...... • 2. Parnassia

I. Ribes L. Gooseberry

I. Stamens longer than the petals and about equalling the

sepals; fruiting stems rarely with bristles on the

middle and upper internodes •• 1. Ribes inerme

1. Stamens about as long as the petals and shorter than

the sepals; fruiting stems usually bristly; leaf-

blades mostly truncate to subcordate

2. Ribes oxvacanthoides

1. Ribes inerme Rydb. Mountain forests; southwestern Alberta.

Now known from riverbottom forest on Waterton River, 1.5 km northeast of the Waterton Lakes National Park boundary, Alberta. Also from moist loam soil in an aspen grove at the mouth of Coalmine Coulee on

St. Mary River, 3 km southwest of Kimball, Alberta. (Shaw 1350,

1418).

2. Ribes oxyacanthoides L. Moist woods. Cook's Ranch on St.

Mary River. (Shaw 793). 138

2. Parnassia L. Grass-of-Parnassus

1. Parnassia palustris L. var. neogaea Fern. Wet places; widespread in region. Town Dam on Lee Creek. (Shaw 1741).

31. LEGUMINOSAE-PEA FAMILY

1. Climbing plants; tendrils at ends of leaves. • 2

1. Plants without tendrils ••••••••••• • 3

2. Style bearded only at the tip ••• 1. Vicia

2. Style bearded along the inner side. 2. Lathyrus

3. Pods (loments) breaking into 1-seeded segments; keel truncate ...... •• 3. Hedysarum 3. Pods not breaking thus; keel not truncate. • • 4 4. Leaves glandular-dotted ...... • 5 4. Leaves not glandular-dotted ...... • 6 5. Stems much branched upwards; flowers in racemes; pods large and prickly •••••• . . . 4. Glycyrrhiza 5. Stems single or branched basally; flowers in dense

cylindrical spikes; fruit small, I-seeded; stamens 5...... 5. Petalostemon 6. Leaflets mostly 5-25, pinnately arranged. • • • 7

6. Leaflets 3-9 (rarely 1), palmately arranged • • • • • • 8

7. Tip of keel with sharp point •••••••••••• 6. Oxytropis

7. Tip of keel rounded •• 7. Astragalus

8. Leaflets 5-9. • 8. Lupinus

8. Leaflets 3 (or 1) • • • • • • 9

9. Leaflets entire. 9. Thermopsis 9. Leaflets with fine teeth ...... 10 139 10. Flowers in slender racemes, 5-10 cm long . . . 10. Melilotus 10. Flowers in oblong clusters or rounded heads, 2-3 cm long . . • ...... 11 11. Pods coiled or curved 11. Medicago

11. Pods straight, covered by calyx 12. Trifolium

1. Vicia L. Vetch

1. Leaflets elliptic to oblong, with the lateral veins at

about 45 degrees to the midrib; flowers usually 5-7; tall plants •••• . . . . . •• 1. Vicia americana 1. Leaflets elongate, narrowly oblong to linear, with

the lateral veins at a very narrow angle to the

midrib; flowers usually 2-4; low plants

2. Vicia sparsifolia

1. Vicia americana Muhl. Open woods, thickets, low grassland.

Cook's Ranch on St. Mary River, Cardston on Lee Creek, and Hillspring

Park on Belly River. (Shaw 748, 661, 833).

2. Vicia sparsifolia Nutt. Commonin prairie grassland.

East of Aetna on St. Mary River. (Shaw 652).

2. Lathyrus L. Pea Vine

1. Flowers yellowish white; leaves glabrous; leaflets 3-4

pairs; stipules large, often half as long as the

leaflets • • • • • • • • • • • • 1. Lathyrus ochroleucus

1. Flowers purple; leaves finely pubescent beneath; leaflets

4-6 pairs; stipules small •••••••• 2. Lathvrus venosus 140

1. Lathyrus ochroleucus Hook. Very common among bushes, in open woods and in northern meadows. Cardwell' s Island on St., Mary

River. (Shaw 843). 2. Lathyrus venosus Muhl. var. intonsus Butters & St. John.

Open woods and moist meadows. Belly River at Monarch. (Shaw 487).

3. Hedys~ L.

1. Leaflets with obscure veins; calyx-lobes about equal,

longer than the tube, linear-subulate; auricles of

wings not united, blunt, much shorter than the claw;

segments of the loment wingless, the areolae trans-

versely elongated •••••••••••• 1. Hedysarum boreale

1. Leaflets conspicuously veined; calyx-lobes markedly unequal,

the upper triangular; auricles of wings united, linear,

about as long as the claw; segments of loment wing-

margined, the areolae about as long as broad ••••••• 2

2. Flowers pinkish or reddish purple; segment~ of loment

3.5-5 mm broad, narrowly wing-margined

2. Hedysarum alpinum

2. Flowers yellowish; segments of loment 6-8 mm broad,

conspicuously wing-margined •• 3. Hedysarum sulphurescens

1. Hedysarum boreale Nutt. Dry banks and hillsides. Cook's

Ranch on St. Mary River and Standoff on Belly River. (Shaw 698, 808).

2. Hedysarum alpinum L. var. americanum Michx. Prairies and open woods. Cardwell's Island on St. Mary River and Slaughter Hole on Lee Creek. (Shaw 960, 1434). 141

3. Hedysarum sulphurescens Rydb. Prairie grassland and mountain woods; southwestern Alberta. Cook's Ranch on St. Mary

River. (Shaw 791).

4. Glycyrrhiza L. Licorice

1. Glycyrrhiza lepidota Pursh. Moist prairie, slopes, shores. Woolford Park on St. Mary River and Slaughter Hole on Lee Creek.

(Shaw 976, 1674).

5. Petalostemon Uichx. Prairie Clover

1. Flowers white; calyx glabrous except the lobes;

leaflets 5-9 •••••• 1. Petalostemon candidum

1. Flowers rose or purple; calyx villose-tomentose;

leaflets 3-5 2. Petalostemon purpureum

1. Petalostemon candidum (Willd.) Michx. Prairie grassland, dry slopes, gravel flats. East of Aetna on St. Mary River. (Shaw

1008).

2. Petalostemon purpureum (Vent.) Rydb. Prairie grassland and eroded slopes. Cardwell's Island on St. Mary River and The

Narrows on Lee Creek. (Sh~w 1926, 1059).

6. Oxytropis DC.

1. Inflorescence and pod glandular-viscid ••• 1. Oxytropis viscida

1. Inflorescence and pod variously pubescent, but not glandular-viscid ...... • • 2 2. Leaves with verticillate leaflets 2. Oxytropis splendens 142

2. Leaves with leaflets opposite or scattered, but

not verticillate • • • • • • • • • • • • • • • • • • • • 3

3. Flowers mostly 12-15 mm long, yellowish; the keel usually

immaculate; foliage green. • • • 3. 0xytropis campestris

3. Flowers mostly 18-25 mm long, whitish (rarely p_urplish)

the keel-tip usually maculate; foliage sericeous

4. 0xytropis sericeus

1. 0xytropis viscida Nutt. Dry banks and hillsides; southern

Alberta. Commonon gravel flats. Woolford Park on St. Mary River,

Town Dam on Lee Creek, and Standoff on Belly River. (Shaw 536, 1268,

461).

2. 0xytropis splendens Dougl. Grassy slopes, open woods and gravelly banks. Cardwell's Island on St. Mary River and Slaughter

Hole on Lee Creek. (Shaw 853, 1436).

3. 0xytropis campestris (L.) DC. var. gracilis (A. Nels.)

Barneby. Conunonin prairie grassland and open woods. Woolford Park on St. Mary River and Town Dam on Lee Creek. (Shaw 979, 1756).

4. 0xytropis sericea Nutt. var. spicata (Hook.) Barneby.

Commonon dry prairie and hillsides. East of Aetna on St. Mary River and Monarch on Belly River_. (Shaw 634, 480).

7. Astragalus L. Milk Vetch

1. Plants with short stems, cushion-like, low-tufted or matted ...... • • 2 1. Plants with elongated stems, either prostrate or erect • 5

2. Flowers 15-20 mm long • • • • • • • • • • • • • • • . • 3 143 2. Flowers smaller, 6-12 mm long; pods reflexed •• . . . . • • 4 3. Plant with stout taproot and short caudex; leaflets mostly

oval, silky-hairy; pods spreading

1. Astragalus missouriensis 3. Plants with slender decumbent stems, forming mats; leaflets

linear-oblong, strigose; pods erect •• 2. Astragalus agrestis

4. Racemes 3-6-flowered; leaflets 7-11; pods sessile

3. Astragalus vexilliflexus

4. Racemes 5-15-flowered; leaflets 13-25; pods short-stipitate ...... 4. Astragalus alpinus 5. Main stems prostrate, or decumbent at base and ascending •••• ...... • 6 5. Main stems erect from the base and mostly tall 12

6. Plants prostrate, the stems wide-spreading. • 7

6. Main stems decumbent at base and ascending. • • • 8

7. Flowers yellowish white, the keel purple-tinged; fruits

globular, fleshy • • • • •• 5. Astragalus crassicarpus

7. Flowers purplish or bluish; pods slender, terete

6. Astragalus flexuosus

8. Low plants, often mat-forming; stems 5-30 cm long ••••• 9

8. Taller plants, often tufted or forming clumps •••• 10

9. Flowers 6-18 mm long in a dense spike-like raceme; pods erect; pubescence basifixed • . . . . • 2. Astragalus agrestis 9. Flowers 7-12 mm long, in a short, open or lax, raceme 4._ Astragalus alpinus

10. Flowers yellowish white (may be purplish); leaflets

linear or narrowly lanceolate 7. Astragalus miser 144 10. Flowers purplish or bluish; leaflets broader ...... 11 11. Raceme lax; flowers 8-11 mm long •••• 8. Astragalus bourgovii

11. Raceme dense, spike-like; flowers 15-18 unn long;

pubescence malpighian •••••••• 9. Astragalus adsurgens 12. Flowers yellowish or whitish (sometimes tipped with purple) • • • • • • • • • • • • • . . . 13 12. Flowers purplish (or pinkish white) • . . . 16 13. Leaflets linear, linear-lanceolate or narrowly oblong 10. Astragalus tenellus

13. Leaflets broader, lanceolate-oblong or elliptic •••••• 14

14. Plant densely and woolly hairy; pod slender-cylindric,

drooping, 2-locular •••• 11. Astragalus drummondii

14. Plant strigose or glabrous; or if woolly, having flat pods ...... • 15 15. Flowers in a spike-like, dense raceme; pods oblong, rather

woody, not stipitate ••••••• 12. Astragalus canadensis

15. Flowers in a more open raceme; pods not woody, on long

stipes 13. Astragalus aboriginum

16. Pod with 2 deep grooves on upper side; raceme dense

14. Astragalus bisulcatus

16. Pod not deeply furrowed on upper side; raceme lax or elongating ••••• ...... 17 17. Pods flattened; plant low and tufted 8. Astragalus bourgovii

17. Pods not markedly flattened; plant usually tall at

maturity 15. Astragalus robinsii

1. Astragalus missouriensis Nutt. Eroded banks, hillsides, 14S gravel-flats; southern Alberta. East of Aetna on St. Mary liver, and

Standoff on Belly River. (Shaw 654, 472).

2. Astragalus agrestis Dougl. Commonin moist grasslands.

Woolford Park on St. Mary River. (Shaw 542).

3. Astragalus vexilliflexus Sheld. Dry slopes, knolls, gravel banks and flats; prairie region of southern Alberta and in the Rocky

Mountains. Highway 5 Bridge on Belly River. (Shaw 1852).

4. Astragalus alpinus L. Moist banks and rocky slopes.

Cook's Ranch on St. Mary River. (Shaw 788).

5. Astragalus crassicarpus Nutt. var. paysoni (Kelso) Barneby.

Dry grassland; East of Aetna on St. Mary River, Slaughter Hole on Lee

Creek, and Standoff on Belly River. (Shaw 653, 1441, 806).

6. Astragalus flexuosus Dougl. Commonon the prairie and dry, gravelly areas. Cardwell's Island on St. Mary River and Standoff on

Belly River. (Shaw 839, 812).

7. Astragalus miser Doug!. var. serotinus (Gray) Barneby.

Dry slopes, thickets and meadows. Cook's Ranch on St. Mary River.

(Shaw 781). 8. Astragalus bourgovii A. Gray. Alpine meadows and elsewhere in the Rocky Mountains. Now known from gravel soil in riverbottom forest at Slaughter Hole on Lee Creek, 0.5 km southwest of

Cardston, Alberta. (Shaw 1688).

9. Astragalus adsurgens Pall. ssp. robustior (Hook.) Welsh.

Connnon on dry prairies, valley slopes, roadsides. Cook's Ranch on

St. Mary River, Town Dam on Lee Creek, and Standoff on Belly River.

(Shaw 804, 1732, 813). 10. Astragalus tenellus Pursh. Dry slopes, eroded banks, 146 river flats. Cardwell's Island on St. Mary River and Highway 5 Bridge on Belly River. (Shaw 852, 1781).

11. Astragalus drummondii Dougl. Open slopes and thickets; southern and central Alberta. East of Aetna on St. Mary River. (Shaw 717).

12. Astragalus canadensis L. Moist open woodlands, banks and shores. East of Aetna on St. Mary River and Town Dam on Lee Creek. (Shaw 874, 1739).

13. Astragalus aboriginum Richards.

= A. aboriginorum Richards. Open woods, stream banks, low meadows. Cardwell's Island on St. Mary River and Town Dam on Lee

Creek. (Shaw 541, 1263).

14. Astragalus bisulcatus (Hook.) A. Gray. Grassland, coulee slopes and valleys. Woolford Park on St. Mary River and Slaughter

Hole on Lee Creek. (Shaw 720, 1444).

15. Astragalus robinsii A. Gray var. minor (Hook.) Bameby.

= A. occidentalis (S. Wats.) M. E. Jones. Moist woodlands and stream banks. Cook's Ranch on St. Mary River and Town Dam on Lee

Creek. (Shaw 738, 1264).

8. Lupinus L.

1. Leaves glabrous or sparsely hairy above; stems and lower leaf surfaces silvery, mostly with short hairs;

standard glabrous or sparsely hairy on the back

1. Lupinus argenteus

1. Leaves densely hairy above; stems and lower leaf surfaces

densely pubescent, often with long silky hairs; 147 standard densely hairy on the back . . . 2. Lupinus sericeus

1. Lupinus argenteus Pursh. Commonon prairie; southern

Alberta. Cardwell's Island on St. Mary River, Slaughter Hole on Lee

Creek, and Highway 5 Bridge on Belly River. (Shaw 959, 1701, 1879).

2. Lupinus sericeus Pursh. Commonon grassland and open forests. East of Aetna on St. Mary River, Slaughter Hole on Lee

Creek, and Highway 5 Bridge on Belly River. (Shaw 492, 718, 1782).

9. Thermopsis R. Br. Buffalo-bean

1. Thermopsis rhombifolia (Nutt.) Richards. Very common in the prairie region, especially on sandy soils. Cook's Ranch on St.

Mary River and Standoff on Belly River. (Shaw 750, 457).

10. Melilotus Hill. Sweet Clover

1. Corolla white; standard somewhat longer than the wings; pod

not wrinkled, but inconspicuously reticulate; seeds

yellow (green when immature) ••••••• 1. Melilotus alba

1. Corolla yellow; standard about equalling the wings; pod

wrinkled; seeds often olive green or purple spotted • • • • • • • • • • • • 2. Melilotus officinalis

1. Melilotus alba Desr. Commonalong roadsides, in waste places and gravel bars. East of Aetna on St. Mary River and

Slaughter Hole on Lee Creek. (Shaw 891, 1718).

2. Melilotus officinalis (L.) Lam. Commonalong roadsides, in waste places and gravel bars. East of Aetna on St. Mary River and 148 Slaughter Hole on Lee Creek, (Shaw 873, 1711).

11. Medicago L.

1. Annual plant; prostrate; corolla yellow, about 3 mm long;

pod slightly curved, kidney-shaped, one-seeded,

becoming black ••••••••••••• 1. Medicago lupulina

1. Perennials; stems erect; corolla 6-10 mm long; pod several-seeded ...... • • • • • • • 2 2. Corolla yellow; pod curved or straight 2. Medicago falcata 2. Corolla violet or blue; pod spirally coiled

3. Medicago sativa

1. Medicago lupulina L. Weed of waste places, fields; sandy soil. East of Aetna on St. Mary River and Slaughter Hole on Lee

Creek. (Shaw 872, 1716). \ 2. Medicago falcata L. Roadsides and waste places. Town Dam

( on Lee Creek. (Shaw 1744).

3. Medicago sativa L. Fields, waste places and roadsides.

East of Aetna on St. Mary River and Town Dam on Lee Creek. (Shaw

869, 1752).

12. Trifolium L. Clover

1. Flowers 12-20 nun long, sessile in the head, usually

reddish; the head subtended by 1 or 2 short- petioled leaves...... 1. Trifoiium pratense 1. Flowers 7-11 mm long, distinctly pedicelled, white or pink;

the head without subtending leaves 2. Trifolium hybridum 149

1. Trifolium pratense L. Sandy soil, moist ground. East of

Aetna on St. Mary River and Town Dam on Lee Creek. (Shaw 1005, 1748).

2. Trifolium hybridum L. Roadsides and waste places. Town

Dam on Lee Creek. (Shaw 1750).

32. VIOLACEAE-VIOLET FAMILY

1. Viola L. Violet

1. Petals white to violet, with a yellow base; stipules

entire • • • • • • • • • • • • • 1. Viola rugulosa

1. Petals blue to violet; stipules often toothed at base ...... 2. Viola adunca

1. Viola rugulosa Greene. Commonin poplar and other woodlands, often forming extensive patches. East of Cardston on St. Mary

River and Highway 5 Bridge on Belly River. (Shaw 674, 515).

2. Viola adunca J.E. Smith. Moist prairie and semi-wooded areas. Woolford Park on St. Mary River and Highway 5 Bridge on Belly

River. (Shaw 535, 513).

33. ANACARDIACEAE-SUMACH FAMILY

1. Rhus L.

1. Rhus trilobata Nutt. Valley slopes and hills. Cook's

Ranch on St. Mary River. (Shaw 802).

34. CRUCIFERAE-MUSTARD FAMILY

1. Petals yellow. • • . . . . . • • • • • 2 1. Petals white or purplish ...... • • • 6 150

2. Pod short, not more than 4 times as long as broad . . . • • 3 2. Pod more than 4 times as long as broad...... • 5 3. Pod conspicuously flattened, elliptic to linear-oblong,

often twisted • 1. Draba 3. Pod not conspicuously flattened...... • • • • 4 4. Pod inflated and bladder-like, constricted in the . middle; basal leaves petiolate, broadly ovate, silvery-pubescent ...... 2. Physaria 4. Pod not inflated and bladder-like • 3. Lesquerella

5. Leaves simple, entire or slightly toothed; stem-hairs

attached by the middle, appressed •••••••• 4. Erysimum

5. Leaves mostly pinnately lobed or finely dissected; stem- hairs not as above ...... 5. Sisymbrium 6. Pod short, not more than 3 times as long as broad • 7 6. Pod more than 3 times as long as broad...... • 8 7. Pod flattened at right angles to the septum (the sutures evident on the broad face) ...... ••• 6. Thlaspi 7. Pod flattened (if at all) parallel to the septum (which is broad) ...... 1. Draba 8. Pod lanceolate to narrowly oblong, rarely over 1.2 cm

long ••• • 1. Draba

8. Pod linear, 1.5-12 cm long 7. Arabis

1. Draba L. Whitlow Grass

1. Draba aurea Vahl. Open forests and alpine areas; Rocky

Mountains. Now known from moist soil in aspen grove at the mouth of

Coalmine Coulee on St. Mary River, 3 km southwest of Kimball, 1S1

Alberta. (Shaw 1429).

2. Physaria (Nutt.) Gray Double Bladder-pod

1. Physaria didymocarpa (Hook.) A. Gray. Dry slopes and plains; western Alberta. East of Aetna on St. Mary River. (Shaw

858).

3. Lesquerella Watson Bladder-pod 1. Pods ovate, usually flattened at apex; pedicels doubly

curved in opposite directions ••••• 1. Lesquerella alpina

1. Pods globose or nearly so; pedicels uniformly recurved

or horizontal ••••••••••••• 2. Lesquerella arenosa

1. Lesquerella alpina (Nutt.) S. Wats. var. spathulata

(Rydb.) Payson. Dry plains and hills. Cook's Ranch on St. Mary

River. (Shaw 792). 2. Lesquerella arenosa (Richards.) Rydb. Hills and plains.

Standoff on Belly River. (Shaw 466).

4. Erysimum L. Wallflower

1. Erysimum cheiranthoides L. River flats and other moist places; also as a weed in fields and gardens. Coalmine Coulee on St.

Mary River. (Shaw 1428).

5. Sisymbrium L.

1. Sisymbrium loeselii •L. Occasional as a weed. Standoff on

Belly River. (Shaw 474). 152 6. Thlaspi L. Stinkweed

1. Thlaspi arvense L. Introduced weed in waste places and

fields. Slaughter Hole on Lee Creek and Standoff on Belly River.

7. Arabis L. Rock Cress

1. Mature fruiting pedicels erect to ascending, never horizontal or reflexed; siliques erect to

ascending •• 1. Arabis hirsuta ·

1. Mature fruiting pedicels diverging at right angles to

strictly reflexed; siliques strictly reflexed •• • • • 2

2. Cauline leaves usually flat, upper glabrous; siliques

2-2.5 mm wide; basal leaves sparsely hairy 2. Arabis holboellii

2. Cauline leaves usually revolute, upper puberulent;

siliques 1-2 mm wide; basal leaves densely

hairy ••••••• 3. Arabis holboellii retrofracta

1. Arabis hirsuta (L.) Scop. var. glabrata T. & G. Ledges, banks, and open woods, moist prairie. Town Dam on Lee Creek. (Shaw

1735).

2. Arabis holboellii Hornem. Relatively uncommon in region.

East of Aetna on St. Mary River and Slaughter Hole on Lee Creek.

(Shaw 1234, 1710).

3. Arabis holboellii Hornem. var. retrofracta (Graham) Rydb.

Prevalent on gravels, sands and rocky slopes. Town Dam on Lee Creek.

(Shaw 1261). 153

35. LINACEAE- FLAXFAMILY

1. Linum L. Flax

1. Linum lewisii Pursh. Plains and hills; comm.on. East of

Aetna on St. Mary River, Slaughter Hole on Lee Creek, and Highway S Bridge on Belly River. (Shaw 636, 1695, 1875).

36. PYROLACEAE-WINTERGREEN FAMILY

1. Pyrola L. Wintergreen

1. Leaves usually as broad as or broader than long, cordate

or truncate at base, dark green and shining above

1. Pyrola asarifolia

1. Leaves usually slightly longer than broad, rounded or

abruptly short-cuneate at base, dull green and

lustreless above 2. Pyrola asarifolia purpurea

1. Pyrola asarifolia Michx. Commonin moist woods. Highway-

5 Bridge on Belly River. (Shaw 1855).

2. Pyrola asarifolia Michx. var. purpurea (Bunge) Fern.

Boggy woods. Cardwell's Island on St. Mary River and Slaughter Hole on Lee Creek. (Shaw 950, 1447).

37. UMBELLIFERAE-CARROT FAMILY

1. Lowest (or all) leaves simple •••••• • 2 1. Lowest leaves (like the upper) compound. . . . • 3 2. Leaves all entire, oblong to linear-lanceolate •• 1. Bupleurum

2. Leaves not entire, the lowest cordate at base and

toothed, the upper ones commonly ternate ••••• 2. Zizia 154

3. Leaves palmate, of 5-7 large leaflets; fruit covered

with short hooked spines; flowers in head-like clusters ...... 3. Sanicula 3. Leaves pinnate or trifoliolate; fruit not as above • • • • 4

4. Fruit linear or nearly so (several times as long as

broad), usually bristly-hairy, glabrous in one species • • • • • • • • • • • • • • • • • • • 4. 0smorhiza

4. Fruit oblong to elliptical, less than 3 times as

long as broad • • • • 5 5. Fruit rounded in cross-section or flattened laterally,

the ribs not winged • • • • • • • • • • • • • • • • • 6

5. Fruit flattened dorsally, some of the ribs (at least the

lateral) or all of them winged •••••••••••••• 7

6. Leaflets or lobes of the leaves linear and entire;

leaves once pinnate • 5. Perideridia

6. Leaflets lanceolate to linear, toothed; leaves twice

pinnate or 2-3-ternate •• 6. Cicuta 7. Leaflets 10-30 cm wide, few; plants conspicuously pubescent

or tomentose; tall stout herb • •• 7. Heracleum

7. Leaflets smaller, less than 5 cm wide, usually numerous;

plant puberulent or _glabrous •••••••••• 8. Lomatium

1. Bupleurum L.

1. Bupleurum americanum Coult & Rose. Dry hillsides and meadows; southwestern Alberta. East of Aetna on St. Mary River.

(Shaw 1007). 155

2. Zizia Koch

1. Zizia aotera (A. Gray) Fern. Moist meadows. East of

Aetna on St. Mary River and Highway 5 Bridge on Belly River. (Shaw 702, 1856).

3. Sanicula L. Snake-root

1. Sanicula marilandica L. Moist thickets and woods. East

of Aetna on St. Mary River. (Shaw 882).

4. Osmorhiza Raf. Sweet Cicely

1. Fruit glabrous, obtuse at base, not caudate; rays ascending

or spreading-ascending; flowers pale yellow

1. Osmorhiza occidentalis 1. Fruit bristly-hispid, the base long-tapering, becoming

caudate with conspicuous tails; rays spreading-

ascending to divaricate; flowers whitish or purplish ••• 2

2. Bractlets of inflorescence present and persistent;

styles 2-3 mm long; fruit 18-22 mm long

2. Osmorhiza longistylis 2. Bractlets absent of very small and caducous; styles

less than 0.5 mm long; fruit 10-20 mm long 3. Osmorhiza depauperata

1. Osmorhiza occidentalis (Nutt.) Torr. Woods; mountains;

southwestern Alberta. Coalmine Coulee on St. Mary River. (Shaw 1431).

I 2. Osmorhiza longistylis (Torr.) DC. Damp woods; not common.

Cardwell's Island on St. Mary River. (Shaw 841a). 156 3. Osmorhiza depauperata Philippi. Wooded areas; frequent.

Cardwell's Island on St. Mary River. (Shaw 841b).

5. Perideridia Reichenb. Yampa 1. Perideridia gairdneri (Hook. & Arn.) Mathias. Meadows and

edges of woodlands; southern Alberta. Cook's Ranch on St. Mary River and The Narrows on Lee Creek. (Sha~ 1044, 2104).

6. Cicuta L. Water Hemlock

1. Cicuta douglasii (DC.) Coult. & Rose. Marshes, stream banks and other wet places; common. Cardwell's Island on St. Mary

River, Town Dam on Lee Creek, and Highway 5 Bridge on Belly River. (Shaw 1115, 1740, 1843).

7. Heracleum L. Cow Parsnip

1. Heracleum lanatum Michx. Rich damp soil; woodlands and

thickets. Slaughter Hole on Lee Creek. (Shaw 1437).

8. Lomatium Raf. Prairie Parsley

1. Leaves with mostly few divisions, ternate or pinnate, the

leaflets mostly remote; plants often caulescent,

tall and slender ••••••••• 1. Lomatium simplex

1. Leaves decompound, dissected into numerous small

divisions and mostly basal on short stems •• • • • • 2

2. Carpels and fruit glabrous, the lateral wings of the

fruit thick and corky; tall plants with large leaves •••••••• ...... 2. Lomatium dissectum 157 2. Carpels and fruit pubescent, glabrate; the lateral

wings thin, not corky; plants acaulescent

3. Lomatium foeniculaceum

1. Lomatium simplex (Nutt.) Macbr. var. leptophyllum (Hook.)

Mathias. Open areas; prairie and mountains. Town Dam on Lee Creek.

(Shaw 1266).

2. Lomatium dissectum (Nutt.) Mathias & Constance var. multifidum (Nutt.) M. & C. Thickets and open rocky slopes; Rocky

Mountains; southwestern Alberta. Coalmine Coulee on St. Mary River.

(Shaw 1421). 3. Lomatium foeniculaceum (Nutt.) Coult. & Rose. Dry prairie grassland and eroded slopes. Woolford Park on St. Mary River. (Shaw 1227).

38. CORNACEAE-DOGWOOD FAMILY

1. Cornus L. 1. Cornus stolonifera Michx. Commonin moist wood~ and on river banks. Woolford Park on St. Mary River, Slaughter Hole on Lee

Creek, and Highway 5 Bridge on Belly River. (Shaw 545, 1211, 1888).

39. ONAGRACEAE-EVENING PRIMROSE FAMILY

1. Fruit 1-seeded, nut-like, indehiscent; flowers somewhat

irregular, white to scarlet •••••••• • 1. Gaura

1. Fruit a many-seeded capsule, opening by valves •••••••• 2

2. Seeds with a tuft of hairs (coma) at one end ••• 2. Epilobium 2. Seeds lacking a coma ...... • 3. Oenothera 158

1. Gaura L.

1. Leaves puberulent ••••• 1. Gaura coccinea

1. Leaves and stems glabrous. • 2. Gaura coccinea glabra

1. Gaura coccinea Pursh. Commonon the prairie; southern

Alberta. Slaughter Hole on Lee Creek and Standoff on Belly River. (Shaw 1443, 809).

2. Gaura coccinea Pursh var. glabra (Lehm.) Torr. & Gray. Commonon the prairie; southern Alberta. The Narrows on Lee Creek.

(Shaw 1062).

2. Epilobium L. Willow-herb

1. Petals 3-8 mm long, usually notched; hypanthium somewhat

prolonged beyond the ovary; stigma not lobed

1. Epilobium glandulosum

1. Petals 10-25 mm long, not notched; hypanthium not

prolonged beyond the ovary; stigma 4-lobed • 2

2. Leaves lanceolate to linear-lanceolate, the lateral veins

conspicuous and looped; racemes many-flowered, not

leafy; style pubescent at base 2. Epilobium angustifolium

2. Leaves broader, the lateral veins obsolete and not

looped; racemes few-flowered, short, leafy;

style glabrous •••••••••• 3. Epilobium latifolium

1. Epilobium glandulosum Lehm. Wet places; common, Town Dam on Lee Creek. (Shaw 1743). 159

2. Epilobium angustifolium L. Open woods and rich disturbed soils, often abundant after fires. Cook's Ranch on St. Mary River. (Shaw 1046).

3. Epilobium latifolium L. Wet places, especially along mountain streams. Woolford Park on St. Mary River and Town Dam on

Lee Creek. (Shaw 975, 1730).

3. Oenothera L. Evening Primrose

I. Plants with elongated stems; flowers bright yellow

1. Oenothera biennis

1. Plants acaulescent or nearly so, the leaves forming a

rosette; flowers white, turning pink in age

2. Oenothera caespitosa

1. Oenothera biennis L. var. hirsutissima Gray. Roadsides, slopes and waste places, especially on lighter soils. Woolford Park on St. Mary River, Slaughter Hole on Lee Creek, and Highway 5 Bridge on Belly River. (Shaw 981, 1691, 1863).

2. Oenothera caespitosa Nutt. Frequent on clay slopes and gumbo flats. East of Aetna on St. Mary River. (Shaw 754).

40. ERICACEAE-HEATH FA..\fILY

1. Arctostaphylos Adams Bearberry

1. Arctostaphylos uva-ursi (L.) Spreng. Commonon sandy soil and rocky ground. Woolford Park on St. Mary River and Highway 5

Bridge on Belly River. (Shaw 5-28, 1861). 160 41. LABIATAE-MINT FAMILY 1. Anther-bearing stamens 2 ...... • 1. Monarda 1. Anther-bearing stamens 4 ...... • • • • • • 2 2. Corolla nearly regular, 4-lobed; stamens equal in

length ••••••••••••••••••••• 2. Mentha

2. Corolla 2-lipped; stamens didynamous • . . 3 3. Calyx deeply 2-lipped, 10-neTVed, the upper lip 3-toothed •••••••••• . . . . . 3. Prunella 3. Calyx not strongly 2-lipped, usually 5-toothed, distinctly nerved •••••••••••••••• 4. Galeopsis

1. Monarda L. Wild Bergamot

1. Monarda fistulosa L. var. menthaefolia (Graham) Fern. Dry

thickets and slopes of valleys. Cardwell's Island on St. Mary River,

Slaughter Hole on Lee Creek, and Highway 5 Bridge on Belly River.

(Shaw 958, 1680, 1871).

2. Mentha L. Mint

1. Mentha arvensis L. var. villosa (Benth.) S. R. Stewart.

Commonin sloughs and other wet places. Cardwell's Island on St.

Mary River, Town Dam on Lee Creek, and Highway 5 Bridge on Belly

River. (Shaw 965, 1742, 1886).

3. Prunella L. Heal-all

1. Prunella vulgaris L. Damp thickets, open woods and

fields. Town Dam on Lee Creek and Hillspring Park on Belly River.

(Shaw 1749, 835). 161

4. Galeopsis L. Hemp Nettle

1. Galeopsis tetrahit L. Weed of waste places, roadsides and fields. Cardwell's Island on St. Mary River. (Shaw 1939).

42. SCROPHULARIACEAE-FIGWORT FAMILY 1. Principal leaves alternate or basal...... • • • 2 1. Principal leaves opposite or whorled • 5

2. Stamens 5; corolla rotate, nearly regular; leaves often

decurrent • • • • • • • • • • • • • • 1. Verbascum

2. Stamens 4; corolla irregular. • • • • 3

3. Corolla spurred or gibbous at base •• 2. Linaria

3. Corolla not spurred or gibbous at base • • • • 4

4. Perennials; flowers large; bracts brightly colored

3. Castilleja

4. Annuals; flowers small; bracts not brightly colored

4. Orthocarpus

5. Calyx 4-toothed, much inflated in fruit; upper lip of corolla arching. • •••••••••••• 5. Rhinanthus

5. Calyx 5-parted; upper lip of corolla erect; sterile stamen present ...... • 6. Penstemon

1. Verbascum L. Mullein

1. Verbascum thapsus L. Roadsides and waste places.

Slaughter Hole on Lee Creek. (Shaw 1692).

2. Linaria (Bauhin) Mill. Toad-flax

1. Linaria vulgaris Hill. Weed of roadsides, fields and 162 waste places. Cook's Ranch on St. Mary River.

3. Castilleja Mutis. Indian Paint-brush

1. Galea usually at least two-thirds as long as the corolla- tube and several times the length of the very short

lip; bracts usually tinged with red or pink (some-

times yellowish) 1. Castilleja miniata

1. Galea less than half as long as the corolla-tube and less

than 3 times as long as the lip; bracts yellow or

yellowish. • • • • • • • • 2. Castilleja septentrionalis

1. Castilleja miniata Dougl. Woodlands, meadows and slopes; widespread and common in wooded regions. Cardwell's Island on St.

Mary River, Town Dam on Lee Creek, and Highway 5 Bridge on Belly

River. (Shaw 964, 17_59, 1881a).

2. Castilleja septentrionalis Lindl. Mountain slopes and fescue prairie grassland; southern Alberta. Cook's Ranch on St. Mary

River and Highway 5 Bridge on Belly River. (Shaw 759, 1835).

4. Orthocarpus Nutt. Owl-clover

1. Orthocarpus luteus Nutt. Commonon dry prairie grassland.

Cardwell's Island on St. Mary River and Town Dam on Lee Creek. (Shaw

1755, 1927).

5. Rhinanthus L. Yellow Rattle

1. Rhinanthus crista-ga-lli L. Meadows and open woodlands.

Highway 5 Bridge on Belly River. (Shaw 1834). 163

6. Penstemon Mitch. Beard-tongue

1. Flowers more than 1 cm long, usually not numerous or

crowded •••• • •••• 1. Penstemon nitidus

1. Flowers mostly less than 1 cm long, numerous in dense

terminal spikes or nodal clusters. • • • • • •••• 2

2. Flowers yellow. • • • ••• 2. Penstemon confertus 2. Flowers blue ••• ...... 3. Penstemon procc~

1. Penstemon nitidus Dougl. Dry hills, eroded areas and banks; southern Alberta. East of Aetna on St. Mary River, Town Dam on

Lee Creek, and Standoff on Belly River. (Shaw 646, 1258, 459).

2. Penstemon confertus Dougl. Grassland, thickets and open woodlands; southern Alberta. Cook's Ranch on St. Mary River. (Shaw 73S).

3. Penstemon procerus Dougl. Low meadows and open woodlands;

central and southern Alberta. Cardwell's Island on St. Mary River.

(Shaw 844).

43. APOCYNACEAE-DOGBANE FAMILY

1. Apocynum L. Dogbane

1. Apocynum cannabinum L. Moist open areas and thickets;

central and southern Alberta. Cardwell's Island on St. Mary River.

(Shaw 846).

44. BORAGINACEAE-BORAGE FAMILY 1. Nutlets with hooked or barbed prickles ...... • • 2 1. Nutlets without hooked or barbed prickles ...... • 4 164

2. Nutlets with prickles covering the dorsal face; flowers

dull red to reddish purple ••••••••• 1. Cynoglossum

2. Nutlets with prickles confined to the margins;

flowers blue or white • • • 3 3. Perennial or biennial; pedicels reflexed in fruit; style

often surpassed by the nutlets • • • • • • 2. Hackelia

3. Annual or winter annual; pedicels erect; style

surpassing the nutlets •••••••••• 3. Lappula

4. Stigma solitary; style not bifid •••••• 4. Cryptantha 4. Stigmas 2 or style bifid •• ...... • • • • 5 5. Flowers greenish white; corolla lobes acute, erect; style

long-exserted at flower opening; anther sagittate

5. Onosmodium

5. Flowers orange or yellowish, sometimes greenish yellow;

corolla-lobes obtuse or rounded; styles included or

finally short-exserted; anthers oblong 6. Lithospermum

1. Cynoglossum L. Hound's-tongue

1. Cynoglossum officinale L. Weed of waste places and past- ures. Cook's Ranch on St. Mary River and Standoff on Belly River.

(Shaw 745, 473).

. 2. Hackelia Opiz. Stick-seed

1. Cauline leaves lanceolate or elliptic-oblong, pointed at

both ends; corolla about 2 mmwide; marginal prickles

of nutlet subulate or slightly flattened

1. Hackelia americana 16S

1. Cauline leaves linear-oblong, broad at base; corolla 4-8

mmwide; marginal prickles of nutlet very flat

2. Hackelia floribunda

1. Hackelia americana (A. Gray) Fern. Thickets and woods; central and northern Alberta. Now known from gravel soil in riverbottom forest, Cook's Ranch on St. Mary River, 3 km north of the

International Boundary, Alberta. (Shaw 751).

2. Hackelia floribunda (Lehm.) I. M. Johnston. Thickets and wooded banks. East of Cardston on St. Mary River. (Shaw 679).

3. Lappula (Riv.) Moench Stick-tights

1. Lappula echinata Gilib. Waste places and fields. Town

Dam on Lee Creek and Hillspring Park on Belly River. (Shaw 838,

1736).

4. Cryptantha Lehm. 1. Cryptantha celosioides (Eastw.) Payson. Dry open areas; sandy soil. Cook's Ranch on St. Mary River and Highway 5 Bridge on

Belly River. (Shaw 755, 1779).

5. 0nosmodium Mx. False Gromwell

1. 0nosmodium occidentale Mackenzie. Sandy prairie, gravel banks and thickets. Standoff on Belly River. (Shaw 810).

6. Lithospermum L. Stone-seed

1. Corolla 10 mm or more long, the tube well surpassing the 166

calyx, bright yellow or orange; nutlets 3-4 mm long

1. Lithospermum incisum

1. Corolla less than 10 mm long, the tube seldom much longer

than the calyx, pale yellow or greenish; nutlets 4-6 mm long ••••••••••••• 2. Lithospermwn ruderale

1. Lithospermum incisum Lehm. Dry hills and plains. Standoff on Belly River. (Shaw 477).

2. Lithospermum ruderale Lehm. Conunonin fescue prairie grassland; southwestern Alberta and Cypress Hills. East of Aetna on

St. Mary River and Town Dam on Lee Creek. (Shaw 650, 1262).

45. GENTIANACEAE-GENTIAN FAMILY

1. Corolla with plaits or folds between the lobes, the lobes

3-veined; nectaries at the base of the ovary 1. Gentiana

1. Corolla without plaits between the lobes, the lobes 5-9-

veined; nectaries upon the base of the corolla-tube

alternate with the stamens •••••••••• 2. Gentianella

1. Gentiana L.

1. Gentiana affini~ Griseb. Moist woodlands and grasslands.

Woolford Park on St. Mary River. (Shaw 2177).

2. Gentianella

1. Gentianella amarella (L.) Borner ssp. acuta (Michx.) J.M.

Gillet. Commonon damp soil; grassy places, thickets, roadsides, wet rocks and banks. Cardwell's Island on St. Mary River. (Shaw 955). 167

46. POLEMONIACEAE- PHLOX FAMILY

1. Leaves simple and entire; plants forming dense tufts or mats...... • 1. Phlox 1. Leaves pinnate ...... 2. Polemonium

1. Phlox L.

1. Phlox hoodii Richards. Commonon dry prairie and hills.

Woolford Park on St. Mary River. (Shaw 1230).

2. Polemonium L.

1. Polemonium pulcherrimum Hook. Rocky slopes and gravelly areas; foothills and mountains; southwestern Alberta. Town Dam on

Lee Creek and Standoff on Belly River. (Shaw 460, 1260).

47. CAMPANULACEAE-BLUEBELL FAMILY

1. Campanula L.

1. Campanula rotundifolia L. Dry meadows, hillsides and open woods; throughout Alberta. East of Aetna on St. Mary River, Slaughter

Hole on Lee Creek, and Highway 5 Bridge on Belly River. (Shaw 868,

1679, 1877).

48. COMPOSITAE-COMPOSITE FAMILY

Key to Groups of Genera

1. Flowers all ligulate and perfect; juice milky Group I

1. Flowers not all ligulate; ray (ligulate) flowers when

present, either pistillate or neutral; juice watery ...... • • • • • • • 2 168 2. Heads radiate ...... • 3 2. Heads discoid (without rays) • • • • • 5

3. Rays yellow or orange (sometimes marked with purple or reddish brown at the base) . . • • • • 4 3. Rays white to pink, purple or blue, not yellow or orange

Group IV

4. Pappus chaffy, or of firm awns, or none; receptacle

chaffy, bristly or naked. • • • • • • Group II

4. Pappus partly or wholly of capillary bristles,

sometimes plumose; receptacle naked • • • Group III

5. Pappus of numerous capillary bristles, sometimes plumose

Group V

5. Pappus of scales, or awns, or very short chaffy bristles,

or a mere crown, or none Group VI

Keys to the Genera in Groups I - VI

Group I

1. Flowers pink, rarely purple or white; plant more or less

rush-like or spinescent, with the leaves mostly linear

or scale-like; principal involucral bracts 4-8

1. Lygodesmia

1. Flowers yellow, or less connnonly orange-red, blue,

purple or white; plants neither rush-like nor

spinescent; involucral bracts various, often more than 8 ...... • . 2 2. Pappus-bristles plumose, the plume-branches interwebbed;

involucre uniseriate •••••••••••• 2. Tragopogon 169 2. Pappus-bristles not plumose; involucre of more than one series...... • • • • 3 3. Plants scapose, the leaves all basal; heads solitary on erect scapes ...... 4 3. Plants more or less leafy-stemmed, though the leaves may

be reduced to_mere bracts, or the whole plant may be

much condensed; heads often more than one •• • • • 5

4. Achenes spinulose or muricate at least towards the

summit, 4-5-ribbed; involucre more or less

calyculate, the bracts in two unequal series

3. Taraxacum

4. Achenes not at all spinulose.or muricate, about 10-nerved; involucral bracts subequal or often

somewhat imbricate in several series. • 4. Agoseris

5. Achenes more or less strongly flattened; flowers yellow or bluish • ...... • • 6 5. Achenes not flattened; flowers yellow •• • 7

6. Achenes beakless, without an enlarged pappus-bearing

disk at the summit; flowers numerous (85-250) in

each head 5. Sonchus

6. Achenes beaked or beakless, in either case somewhat

enlarged at the summit where the pappus is attached;

flowers 10-60 in each head ••••••••••• 6. Lactuca

7. Pappus mostly sordid or brownish; plants fibrous-rooted

from a short rootstock or caudex •••••• 7. Hieracium

7. Pappus mostly white; plants ·tap-rooted or with several

strong roots ••••••••••••••••••• 8. Crepis 170 Group II

1. Plants with a woody caudex; leaves linear; involucre glandular-glutinous. . . . . • • 9. Gutierrezia 1. Plants not as above ••• ...... • • • • 2 2. Plants scapose or scapiform perennials, the cauline

leaves none, o.r few and reduced to mere bracts ••••• 3

2. Plants more or less leafy-stemmed • 4

3. Leaves oblanceolate, up to 1 cm wide; receptacle naked

10. Hymenoxys

3. Leaves long-petioled, the blades triangular, up to 15 cm

wide; receptacle chaffy. • 11. Balsamorhiza 4. Receptacle naked •• . . . • 5 4. Receptacle chaffy or bristly...... • 6 5. Pappus of a few firm deciduous awns; involucres strongly resinous ...... 12. Grindelia 5. Pappus of chaffy or scarious scales, or a mere crown,

or none; involucre not resinous, though sometimes

glandular-puberulent 10. Hymenoxys.

6. Receptacle merely bristly; leaves alternate •• 13. Gaillardia

6. Receptacle chaffy • • • • 7

7. Receptacle flat or convex; at least the lower leaves opposite ...... 14. Helianthus 7. Receptacle conic or columnar; leaves all alternate • • • • 8

8. Rays subtended by receptacular bracts; achenes

flattened laterally and margined. 15. Ratibida I 8. Rays not subtended by receptacular bracts; achenes 4-sided, marginless ...... 16. Rudbeckia 171

Group III

1. Leaves opposite (except sometimes the reduced uppermost ones) • • • • ...... • 17. Arnica 1. Leaves alternate, or all basal . . • • 2 2. Pappus double, the outer inconspicuous and very much shorter than the inner •••••• . . . . . • • • • 3 2. Pappus simple, the bristles sometimes unequal, but not distinctly divided into two lengths ...... • • • 4 3. Low plants; cauline leaves few; heads solitary • 18. Erigeron

3. Taller plants; cauline leaves many; heads several

19. Chrysopsis

4. Involucral bracts uniseriate, equal, narrow, commonly

with a few very much shorter outer ones at the base • . . . . 20. Senecio 4. Involucral bracts either imbricate in several series,

or broad and somewhat leafy, or both; fibrous-

rooted herbs ••••••••••••••••• 21. Solidago

Group IV

1. Pappus at least in part, of capillary bristles; receptacle naked ...... • • • 2 1. Pappus of scales, or awns, or flattened, chaffy bristles, or a mere crown or none...... • • • 3 2. Involucral bracts subequal or more or less imbricate,

often green in part, but neither definitely leafy

nor with chartaceous base and herbaceous green tip;

style-branches lanceolate or broader, acute to 172

obtuse, 0.5 mm long or less, or obsolete ••• 18. Erigeron

2. Involucral bracts either subequal and the outer leafy,

or more commonly evidently imbricate, with chart-

aceous base and evident green tip, sometimes

chartaceous throughout; style-branches lanceolate

or narrower, acute or acuminate, ordinarily more . than 0.5 mm long...... 22. Aster 3. Leaves entire; pappus of numerous bristle-like scales; rays purple, blue or pink; receptacle naked •• 23. Townsendia

3. Leaves conspicuously toothed to pinnately dissected

(or the upper sometimes entire) • • • • 4 4. Rays purple; receptacle chaffy ••• ...... • 15. Ratibida 4. Rays white (rarely pink in Achillea) • • • • 5

5. Leaves toothed, incised or pinnatifid. 24. Chrysanthemum

5. Leaves all pinnately dissected • •• 25. Achillea

Group V 1. Receptacle densely bristly ...... 26. Cirsium 1. Receptacle naked ...... • 2 2. Outer flowers, or all flowers of some heads, pistillate 27. Antennaria 2. Flowers all perfect . . . . • • • • 3 3. Flowers white to pink or purple, not yellow or orange 28. Liatris 3. Flowers yellow or orange ...... • • • • • 4 4. Leaves (except sometimes the reduced uppermost ones) opposite...... 17. Arnica 173

4. Leaves alternate (sometimes nearly all basal) • • • 5 5. Involucral bracts equal, in essentially a single series,

often with some much shorter ones as a calyculum at

the base •••••••••••••••••••• 20. Senecio 5. Involucral bracts in more than one series, sometimes

imbricate, but without a calyculum 18. Erigeron

Group VI

1. At least some of the involucres armed with short, hooked prickles ••••••••••••••••• 29. Arctium

1. None of the involucres armed with hooked prickles,

although they may have straight spines •••••••••• 2

2. Involucre strongly resinous; pappus of a few firm,

deciduous awns. • • • • • ••••••• 12. Grindelia

2. Involucre not st~ongly resinous, though sometimes

with glandular pubescence, pappus otherwise

30. Artemisia

1. Lygodesmia D. Don Skeleton-weed

1. Lygodesmia juncea (Pursh) D. Don. Dry open places, especially sandy soil. Cardwell's Island on St. Mary River. (Shaw

1136).

2. Tragopogon L. Goat's-beard

1. Tragopogon dubius Scop. A weed of roadsides and waste places; common; southern Alberta. Cook's Ranch on St. Mary River,

Slaughter Hole on Lee Creek, and Standoff on Belly River. (Shaw

820, 1042, 1697). 174 3. Taraxacum Hall Dandelion

1. Taraxacum officinale Weber. A cosmopolitan weed of lawns, fields and waste places. Cook's Ranch on St. Mary River. (Shaw 1041).

4. Agoseris Raf. False Dandelion 1. Agoseris glauca (Pursh) Raf. Prairies, meadows and mountain slopes. Cardwell's Island on St. Mary River, Slaughter Hole on Lee Creek, and Highway 5 Bridge on Belly River. (Shaw 961, 1687, 1869).

5. Sonchus L. Sow Thistle

1. Perennials, spreading by long horizontal roots; heads 3-S

cm wide in flower; fruiting involucre 14-24 mmhigh 1. Sonchus uliginosus

1. Annuals; heads 1.5-2.5 cm wide; fruiting involucre 9-13

mm high, glabrous •••••••••••••• 2. Sonchus asper

1. Sonchus uliginosus Bieb. A cosmopolitan weed; now very common in Alberta. Woolford Park on St. Mary River. (Shaw 977).

2. Sonchus asper (L.) Hill. A common weed of gardens and waste places. Cardwell's Island on St. Mary River. (Shaw 1937).

6. Lactuca L. Lettuce

1. Lactuca serriola L. Commonintroduced weed of roadsides and waste places. Town Dam on Lee Creek. (Shaw 1730). 175 7. Hieracium L. Hawkweed

1. Basal or lower cauline leaves much larger than the progressively

smaller middle and upper ones; involucral pubescence

glandular ••••••••••••• 1. Hieracium cynoglossoides 1. Basal and lowermost cauline leaves small and soon deciduous,

the middle leaves numerous, large, similar in size and

shape (the upper ones often markedly reduced) • • • 2 2. Leaves lanceolate to narrowly ovate, mostly rounded to

subcordate at base, usually toothed and without short

stout marginal hairs; inflorescence paniculate-

corymbose; involucres often with a few glandular hairs;

stem usually long-hairy near base

2. Hieracium canadense

2. Leaves linear to narrowly lanceolate, tapering to base,

the margins entire or distinctly toothed, scabrous

with short stout marginal hairs; inflorescence often

somewhat umbellate above; inflorescence without glands;

stem usually without long, spreading hairs

3. Hieracium umbellatum

1. Hieracium cynoglossoides Arv.-Touv. Dry open places in foothills and mountains; southwestern Alberta. Highway 5 Bridge on

Belly River. (Shaw 1836).

2. Hieracium canadense Michx. Thickets, open woods and clearings. Cardwell's Island on St. Mary River. (Shaw 1111).

3. Hieracium umbellatum L. Thickets, open woodlands and low meadows. Cook's Ranch on St. Mary River, Town Dam on Lee Creek, and 176 Highway 5 Bridge on Belly River. (Shaw 1036, 1757, 1783).

8. Crepis L. Hawksbeard

1. Crepis intermedia A. Gray. Dry ground; hills and mountains; southern Alberta. Highway 5 Bridge on Belly River. (Shaw 1847).

9. Gutierrezia Lag. Broomweed

1. Gutierrezia sarothrae (Pursh) Britt. & Rusby. Commonon dry prairies. Cook's Ranch on St. Mary River. (Shaw 560).

10. Hymenoxys Cass.

1. Leaves all basal, entire; heads solitary on unbranched stalks;

involucral bracts similar, in 2 or 3 indefinite series, none united. • ••••••••••• 1. Hymenoxys acaulis

1. Leaves both basal and cauline, 3-7-divided into linear

segments; heads 1-many, in flat-topped corymbs;

involucral bracts dissimilar, in 2 definite series,

the outer ones partly united 2. Hymenoxys richardsonii

1. Hymenoxys acaulis (Pursh) Parker. Eroded hillsides; southern Alberta. Coalmine Coulee on St. Mary River and Slaughter

Hole on Lee Creek. (Shaw 1422, 1719).

2. Hymenoxys richardsonii (Hook.) Cockerell. Commonon dry prairie; southern Alberta. Kimball Park on St. Mary River. (Shaw

2362). 177

11. Balsamorhiza Nutt.

1. Balsamorhiza sagittata (Pursh) Nutt. Prairie grassland and open woods; southwestern Alberta. Cook's Ranch on St. Mary River.

(Shaw 741).

12. Grindelia W. Gumweed

1. Grindelia squarrosa (Pursh) Dunal var. quasiperennis

Lunell. C~11lI!lonon dry prairie, especially somewhat saline flats and denuded areas. Cardwell's Island on St. Mary River. (Shaw 1108).

13. Gaillardia Foug.

1. Gaillardia aristata Pursh. Prairie grassland and other open dry places. Slaughter Hole on Lee Creek and Highway 5 Bridge on

Belly River. (Shaw 1673, 1876).

14. Helianthus L. Sunflower

1. Annuals; leaves mostly alternate; disk purple or dark brown;

receptacle flat or nearly so 1. Helianthus annuus

1. Perennials; leaves mostly opposite; disk various; receptacle

convex or low-conical. • • 2

2. Disk purple, red or dark brown; involucral bracts broad,

firm, appressed; larger leaves somewhat rhombic 2. Helianthus laetiflorus

2. Disk yellow or light brown; involucral bracts narrow,

mostly with loose acuminate tips; leaves generally lanceolate •••••••••••• 3. Helianthus nuttallii 178 1. Helianthus annuus L. ssp. lenticularis (Dougl.) Cockerell.

Quite common as a weed on roadsides and waste places, especially in southeastern Alberta. Cardwell's Island on St. Mary River. (Shaw

1932).

2. Helianthus laetiflorus Pers. var. subrhomboideus (Rydb.)

Fern. Valleys, moist prairies and roadsides. The Narrows on Lee Creek. (Shaw 2102).

3. Relianthus nuttallii T. & G. Commonin low meadows and other moist places. Woolford Park on St. Mary River. (Shaw 1149).

15. Ratibida Raf. Cone-flower 1. Ratibida columnifera (Nutt.) Wooton & Stand!. Dry prairie. East of Aetna on St. Mary River and Slaughter Hole on Lee Creek.

(Shaw 1011, 1671).

16. Rudbeckia L. Black-eyed Susan

1. Rudbeckia serotina Nutt. Low meadows and disturbed areas; not common in Alberta. East of Aetna on St. Mary River. (Shaw 866).

17. Arnica L.

1. Cauline leaves mostly 5-10 pairs; pappus straw-colored

or brownish, barbellate •••••••••• 1. Arnica fulgens

1. Cauline leaves mostly 2-4 pairs, not including those (if

any) of the basal cluster; pappus various (often white and plumose) ...... •• 2. Arnica cordifolia

1. Arnica fulgens Pursh. Open places; widespread in Alberta. 179

Highway 5 Bridge on Belly River. (Shaw 1881).

2. Amica cordifolia Hook. Connnonin woodlands; western

Alberta and Cypress Hills. Coalmine Coulee on St. Mary River. (Shaw

1426).

18. Erigeron L. Fleabane

1. Leaves, or some of them, more or less lobed, cleft or

coarsely toothed; stems scapose or subscapose

1. Erigeron compositus

1. Leaves not lobed, mostly entire, sometimes toothed at

apex • • • • • • • • • • • • • • • • • • • • • • • • . 2

2. Ligules absent or short, not over 4 mm long at

maturity . . • ...... • • • 3

2. Ligules present, generally conspicuous, over 4 mm long at maturity ...... • • • 4 3. Involucral bracts 2-6 mm long; plants annual or biennial;

leaves sparse • • • 2. Erigeron strigosus

3. Involucral bracts 4-10 mm long; plants biennial or

perennial; cauline leaves narrowly lanceolate or

broader, rarely linear •••••••••• 3. Erigeron acris

4. Long pappus bristle~ lacking on the outer pistillate

{usually ligulate) flowers; ligule~ often

inconspicuous ••••••••••• 2. Erigeron strigosus

4. Long pappus bristles present on all the flowers of the head; ligules usually conspicuous ...... • . . 5 5. Annual, biennial or short-lived perennial plants, without

rootstocks or well developed caudex

4. Erigeron philadelphicus 180 5. Perennials, usually with short rootstocks or well developed

caudex, this often woody or branching ••••••••••• 6

6. Cauline leaves little reduced in size and number upwards.

ample, usually lanceolate or broader; stems erect, often over 3.5 dm tall ••• ...... • • 7 6. Cauline leaves much reduced in size and number upwards, mostly linear, lanceolate or oblanceolate; stems often

spreading or decumbent at base, mostly less than 3.5

dm tall ...... 9

7. Ligules 2-4 mm wide; pappus not definitely double; achenes

4-7-nerved •••••••••••••• 5. Erigeron peregrinus

7. Ligules rarely over 2 mmwide; pappus double; achenes

2-4-nerved ...... 8

8. Leaf surfaces hairy (atleast on the main veins);

stems hairy throughout •••••• 6. Erigeron caespitosus

8. Leaf surfaces glabrous but the margins ciliate; stems

glabrous below, glandular or sparsely hairy above

7. Erigeron speciosus

9. Ligules often over 2.5 mmwide; pappus not definitely

double; achenes 4-7-nerved •••••• 5. Erigeron peregrinus

9. Ligules rarely over 2.5 mmwide; pappus double; achenes

usually 2-nerved • • • • •••••••••••••• 10

10. Plant without a taproot but with fibrous roots from a

well developed caudex; ligules often over 100 to a

head, about 1 mmwide • • • • 8. Erigeron glabellus

10. Plant with a taproot as well as a caudex and lacking

fibrous roots; ligules not over 100 to a head, 181

usually over 1 mmwide • ••••• 6. Erigeron caespitosus

1. Erigeron compositus Pursh var. glabrata Macoun. Common, mostly on rocky areas, in the Rocky Mountains; also eastward to the

Cypress Hills. East of Aetna on St. Mary River and Standoff on Belly

River. (Shaw 648, 471).

2. Erigeron strigosus Muhl. A weed of roadsides and waste places. Cardwell's Island on St. Mary River and Slaughter Hole on

Lee Creek. (Shaw 972, 1698).

3. Erigeron acris L. Woods and mountains. Cardwell's Island on St. Mary River.

4. Erigeron philadelphicus L. Moist places; open woodlands, stream banks. Woolford Park on St. Mary River. (Shaw 551).

5. Erigeron peregrinus (Pursh) Greene ssp. callianthemus

(Greene) Cronq. Moist banks, meadows and open woods in the mountains. Now known from riverbottom forest at Cook's Ranch on St.

Mary River, 3 km north of the International Boundary, Alberta. Also from gravel soil in riverbottom forest at Slaughter Hole on Lee Creek,

0.5 km southwest of Cardston, Alberta. (Shaw 1015, 1039, 1708).

6. Erigeron caespitosus Nutt. Dry open places; a common prairie species. Cardwell_'s Island on St. Mary River, Slaughter Hole on Lee Creek, and Highway 5 Bridge on Belly River. (Shaw 1~24, 1714,

1886).

7. Erigeron speciosus (Lindl.) DC. Moist meadows in mountains of southwestern Alberta. Now known from gravel soil in riverbottom forest at Town Dam on Lee Creek, 8 1cm southwest of Cardston, Alberta.

Also from gravel soil in riverbottom forest at Highway 5 Bridge on 182

Belly River, 8 km west of Mountain View, Alberta. (Shaw 1760, 1874).

8. Erigeron glabellus Nutt. var. pubescens (Hook.) Cronq.

Meadows and prairies. East of Aetna on St. Mary River. (Shaw 878).

19. Chr~sopsis Nutt.

1. Chrysopsis villosa (Pursh) Nutt. var. hispida (Hook.) Gray.

Commonin dry open places, especially on sandy soil. Cardwell's

Island on St. Mary River, Town Dam on Lee Creek, and Standoff on

Belly River. (Shaw 1137, 2178, 816).

20. Senecio L.

1. Plants more or less pubescent at flowering time •••••••• 2

1. Plants glabrous from the first; or, floccose-tomentose when

young and becoming glabrous except occasionally for some

tomentum in the leaf axils, or elsewhere • 3

2. Pubescence loosely villose, either crisp or arachnoid,

sometimes sparse by flowering time; robust plant

with large inflorescence of many heads 1. Senecio integerrimus

2. Pubescence very fine, tomentose or floccose-tomentose;

smaller plants; heads !-several ••••• 2. Senecio canus

3. Leaves entire, denticulate or sharply dentate, not at all

pinnatifid, lobed, undulate or crenate, often glaucescent;

plants tall but slender. • • • • • • • 3. Senecio lugens

3. Leaves, or some of them, pinnatifid, lyrate, undulate

or crenate • • • • • • .• • • • • • • • 4. Senecio pauperculus 183

1. Senecio integerrimus Nutt. var. exaltatus (Nutt.) Cronq.

Moist prairie and open places in the mountains. Slaughter Hole on

Lee Creek. (Shaw 1438).

2. Senecio canus Hook. Dry open places; prairie, foothills and mountains. Cook's Ranch on St. Mary River and Standoff on Belly

River. (Shaw 765, 470).

3. Senecio lugens Richards. Moist woodlands and boggy places.

Town Dam on Lee Creek and Highway 5 Bridge on Belly River. (Shaw

1751, 1873).

4. Senecio pauperculus Michx. Low meadows and boggy places.

Cook's Ranch on St. Mary River. (Shaw 1013).

21. Solidago L. Goldenrod

1. Heads in dense cymose clusters, these arranged in a flat-

topped or corymb-like inflorescence

1. Solidago graminifolia

1. Heads racemose, or panicled with racemose branches • • 2

2. Leaves 1-nerved; heads not at all secund; stems usually

glabrous, at least below ••••••• • • 3

2. Leaves 3-nerved; {1 pair of lateral nerves fairly

prominent); heads usually secund ••• • • • 4

3. Involucral bracts linear-lanceolate or lanceolate, acute

or acuminate; inflorescence often with rather long

peduncles; leaves villose-ciliate, at least near their bases • ...... 2. Solidago multiradiata I 3. Involucral bracts oblong to linear-oblong, obtuse;

inflorescence congested, often cylindrical; leaves 184

not ciliate ••••••••• 3. Solidago decumbens oreophila

4. Plants 2-4 dm tall, the cauline leaves rather few;

leaves oblanceolate to spatulate, entire or sometimes toothed • • • • • 4. Solidago missouriensis 4. Plants 5-20 dm tall, the cauline leaves numerous;

leaves lanceolate, usually serrate •• 5. Solidago gigantea

1. Solidago graminifolia (L.) Salish. var. major (Michx.)

Fern. Low meadows and shores. Cardwell's Island on St. Mary River.

(Shaw 194 7) •

2. Solidago multiradiata Ait. Alpine slopes and peaty a1:eas; western and northern Alberta. Now known from riverbottom forest on

Cardwell's Island, St. Mary River, 8 km southeast of Cardston,

Alberta. Also from sandy soil of banks and slopes, St. Mary River,

11 km. northwest of Magrath, Alberta, and gravel bar on Lee Creek, 0.5 km west of old ranger station, Poll Haven Community Pasture, southwest Alberta. (Shaw 940, 1642, 1534).

3. Solidago decumbens Greene var. oreophila (Rydb.) Fern.

= !• spathulata DC. Commonin prairie grassland and open woods. Cook's Ranch on St. Mary River and The Narrows on Lee Creek.

(Shaw 787, 2100).

4. Solidago missouriensis Nutt. Commonin prairie grassland and open woods. Cardwell's Island on St. Mary River and Slaughter

Hole on Lee Creek. (Shaw 1112, 1676).

5. Solidago gigantea Ait. Thickets, open woods, alluvial flats and shores. Cook's Ranch on St. Mary River and Highway 5

Bridge on Belly River. (Shaw 1030, 1885). 18S

22. Aster L.

1. Bracts usually very pubescent on back, bristle-tipped. squarrose •••••••••• ...... 1. Aster pansus 1. Bracts mostly glabrous except the ciliate margins . • 2

2. Lower leaves long-petioled; blades ovate to lanceolate,

often cordate, more or less serrate; bracts attenuate,

with green midrib and scarious margins

2. Aster ciliolatus

2. Lower leaves oblanceolate, linear or lanceolate, mostly sessile or nearly so...... • • 3 3. Plants glabrous throughout; upper leaves clasping, the

lower wing-petioled; bracts white-coriaceous below

3. Aster laevis

3. Plants with at least some pubescence on upper parts of

the stems, uniformly distributed; leaves linear to

oblong • • • • • • • • • • • • • 4. Aster occidentalis

1. Aster pansus (Blake) Cronq. Prairie grassland and other

open places. Cardwell's Island on St. Mary River and Town Dam on Lee

Creek. (Shaw 1114, 2175).

2. Aster ciliolatus Lindl. Woods and thickets. Cook's Ranch

on St. Mary River. (Shaw 1028).

3. Aster laevis L. var. geyeri A. Gray. Open places; a common

and showy plant. Cardwell's Island on St. Mary River and The Narrows

on Lee Creek. (Shaw 1113, 2097).

4. Aster occidentalis (Nutt.) T. & G. Meadows, hillsides and banks; not common. Woolford Park on St. Mary River and Slaughter 186 Hole on Lee Creek. (Shaw 2178, 1702).

23. Townsendia Hooker

1. Townsendia parryi D. C. Eat. Dry hills and banks; southwestern Alberta. East of Aetna on St. Mary River. (Shaw 632).

24. Chrysanthemum L. Ox-eye Daisy

1. Chrysanthemum leucanthemum L. Weed of meadows, roadsides and waste places; reported for a few localities in Alberta.

Cardwell's Island on St. Mary River, Slaughter Hole on Lee Creek. and

Hillspring Park on Belly River. (Shaw 952, 1696, 836).

25. Achillea L. Yarrow

1. Achillea millefolium L. var. lanulosa (Nutt.) Piper.

Commonplant of the prairie and roadsides. Cook's Ranch on St. Mary

River, Slaughter Hole on Lee Creek, and Highway 5 Bridge on Belly

River. (Shaw 757, 1672, 1878).

26. Cirsium Miller Thistle

1. Perennial with deep-seated and widely creeping roots;

heads unisexual, relatively small, the involucre

1-2 cm high •••••••• ••••• 1. Cirsium arvense

1. Biennial or perennial, mostly without creeping roots,

the flowering stem arising from last year's basal

rosette; heads with perfect flowers, usually larger •••• 2

2. Stem conspicuously winged by prickly, pinnatifid or

undulate leaf bases, the wings about as long as 187

the internodes; leaves scabrous-hispid and green

above ••••••••••••••••• 2. Cirsium vulgare

2. Stem without decurrent leaf bases, or very short

winged; leaves arachnoid-villose, tomentose or glabrate above, not scabrous-hispid

3. Cirsium undulatum

1. Cirsium arvense (L.) Scop. A noxious weed of fields and roadsides. Cardwell's Island on St. Mary River. (Shaw 1922).

2. Cirsium vs:are (Savi) Airy-Shaw. Introduced weed now established in many p ces. Cardwell's Island on St. Mary River.

(Shaw 1923) •

3. Cirsium undulatum (Nutt.) Spreng. Dry open places, mostly in southern Alberta. Cook's Ranch on St. Mary River and Slaughter

Hole on Lee Creek. (Shaw 1017, 1689).

27. Antennaria Gaertner Pussy-toes

1. Antennaria rosea Greene. Commonin open places. Cook's

Ranch on St. Mary River and Slaughter Hole on Lee Creek. (Shaw 753).

28. Liatris Schreber

1. Liatris punctata Hook. Commonon dry plains and hills; southern Alberta. Cardwell's Island on St. Mary River, Town Dam on

Lee Creek, and Highway 5 Bridge on Belly River. (Shaw 1135, 2174,

1848).

29. Arctium L. Burdock 188 1. Arctium minus (Hill) Bernh. Established as a weed locally in waste places. Cook's Ranch on St. Mary River. (Shaw 1021).

30. Artemisia L. Sagebrush

1. Central flowers sterile, with abortive ovary; receptacle naked ••• ...... 1. Artemisia campestris 1. Central flowers fertile, with normal ovary • • • • 2

2. Biennial or annual, with a taproot; leaves essentially

glabrous, the lower mostly bipinnatifid

2. Artemisia biennis

2. Perennials; leaves more or less tomentose, at least beneath ...... • • • • • 3 3. Stems commonly from creeping rootstocks; lower leaves

oblanceolate to linear-lanceolate; a common prairie

species •••• ••••• 3. Artemisia ludoviciana 3. Stems from a coarse woody base; leaves linear to lanceolate,

acuminate, often with rolled margins; badlands and

eroded slopes •••••••••••• 4. Artemisia longifolia

1. Artemisia campestris L. ssp. caudata (Michx.) H. & C.

Commonin sandy ground; plains, hills and mountain slopes. East of Aetna on St. Mary River and Slaughter Hole on Lee Creek. (Shaw 1009,

1717).

2. Artemisia biennis Willd. Moist places; native, but often weed-like on disturbed areas. Slaughter Hole on Lee Creek and

Highway 5 Bridge on Belly River. (Shaw 1713, 1864).

3. Artemisia ludoviciana Nutt. Gravel bar in riverbottom 189 forest; Town Dam on Lee Creek. (Shaw 1733).

4. Artemisia longifolia Nutt. Eroded slopes and dry saline areas. Cardwell's Island on St. Mary River. (Shaw 1929).

49. CAPRIFOLIACEAE-HONEYSUCKLE FA.~ILY

1. Corolla bell-shaped, regular; fruit a berry-like drupe, usually 2-seeded, whitish ...... 1. Symphoricarpos 1. Corolla tubular, more or less irregular; berry several-

seeded, not white . . • ...... • ...... 2. Lonicera

1. Symphoricarpos Juss. Snowberry

1. Symphoricarpos occidentalis Hook. Very common on the prairie, in thickets and on the borders of aspen groves. Cook's Ranch on St. Mary River, Town Dam on Lee Creek, and Standoff on

Belly River. (Shaw 578, 1159, 1199).

2. Lonicera L. Honeysuckle

1. Stems twining or reclining; flowers conspicuous, yellow to

reddish, in terminal clusters; fruit red; upper leaves connate •• • 1. Lonicera dioica

1. Stems erect; flowers in pairs on axillary peduncles; leaves all separate ...... • • 2 2. Bracts at base of flowers large and leaf-like, at least

in fruit; corolla almost regular; berries of the

paired flowers separate 2. Lonicera involucrata 2. Bracts small and inconspicuous; corolla 2-lipped; berries

of the paired flowers more or less united; introduced 190

ornamental; flowers pink or white; berry red or yellow

3. Lonicera tartarica

1. Lonicera dioica L. var. glaucescens (Rydb.) Butters. Open forest and bluffs. Coalmine Coulee on St. Mary River. (Shaw 1423).

2. Lonicera involucrata (Richards.) Banks. Low woods and moist banks. Highway 5 Bridge on Belly River. (Shaw 1839).

3. Lonicera tartarica L. Growing occasionally as an escape from cultivation. Slaughter Hole on Lee Creek. (Shaw 1449).

50. RUBIACEAE-MADDER FAMILY

1. Galium L. Bedstraw

1. Leaves mostly in whorls of 8; annual; flowers greenish-

white ••••••••••••••••••• 1. Galium aparine

1. Leaves mostly in whorls of 4 or 6; corolla whitish

2. Galium boreale

1. Galium aparine L. var. echinospermum (Wallr.) Farwell. River banks, moist woodlands and cultivated fields. Cardwell's

Island on St. Mary River. (Shaw 842). 2. Galium boreale L. Very common in woodlands, on moister parts of prairies and on roadsides. Cook's Ranch on St. Mary River,

Town Dam on Lee Creek, and Highway 5 Bridge on Belly River. (Shaw

798, 1758, 1880). DISCUSSION

The rather widely held belief that native cottonwood species have not populated the prairies of southwest Alberta because of lack of shelter from the wind is open to closer scrutiny. Native poplar and cottonwood species have been successfully transplanted from natural riverbottom forest populations to prairie grassland sites.

Furthermore, hybrid and exotic poplar species have been planted with excellent success on the prairies during the past 80 years. The barrier to native poplar invasion of the grasslands is partly a reproductive one. Mature trees in yard and shelterbelt plantings produce quantities of seeds but these observedly have failed to produce new plants. The seeds of native poplars are transported far and wide by the generous wind. If lack of shelter is the only factor responsible for the failure of poplar seedling survival then there must surely be evidence of seed germination and partial seedling growth on some parts of the prairie grassland. No such evidence was found.

However, seeds from southwest Alberta riverbottom forest poplar species will readily germinate and grow if they are provided with two essential environmental conditions in addition to the obvious ones of temperature, etc. First, there must be gravel beds or bars with a make-up of about 40% sand {particles less than 0.5 cm in diameter) and 60% rock; and ·second, these gravel beds or bars must be water saturated to the surface at frequent intervals during the 192 growing season and there must be a high water table, within four to ten decimeters of the surface, at other times.

The necessity for the gravel to be in streamside bars is not absolute since poplar seeds have readily germinated and developed into trees in abandoned high water table gravel pits on the prairies, for example, 1.5 km west of Fort Macleod and 1.5 km west of Cardston. These trees are poorly sheltered from the wind.

New gravel bars saturated with water on the streams of southwest Alberta are quickly populated by seedlings of riverbottom forest poplar species. These are capable of developing into mature forest trees if the gravel bar or terrace remains intact.

High quality loam soil with high soil moisture will not produce forest growth. Such sites on the sheltered high banks of rivers and coulees may have tangled thickets of serviceberry, choke- cherry, honeysuckle and hawthorn but rarely are there poplars growing with them.

In southwest Alberta, streams such as Rolph Creek, Snake Creek and Boundary Creek plus some sections of the north and south forks of

Milk River have high water tables in bankside sand-silt soils yet they are without riverbottom forest. They are well within the survival and seed dissemination ranges of native poplars.

Gravel banks and perched ancient river valley terraces, with gravel in abundance, having sub-surface drainage are without riverbottom forest. River valley gravel bars formed by unusually high flood waters and left too high for sub-surface water saturation will also fail to develop riverbottom forest stands. Herbaceous species may be quite successful on such sites, however. 193

Streams flowing in very shallow valleys, for example the

Little Bow River, or in very open coulees like Pinepound Coulee, are without rlverbottom forest not entirely because of exposure to the wind but because the necessary high water table streamside gravels are not available.

Stream systems also provide excellent seed dispersal mechanisms. Flowing water will bring mountain or sub-montane species to greater range extensions down the valleys. Wind borne seeds are readily dropped in the lee of sheltering banks and thickets where wind velocity decreases. Bird activities provide other transport mechanisms. Downstream species are able to extend their ranges upstream nearly as readily.

As a result of constant erosion, deposition and channel- shifting by ·the three southwest Alberta streams included in this study, stability of many of the gravel bars is not maintained for long. Fresh bars of material sorted into various textures and of varying depths annually become available for colonization. Older deposits may be removed or stripped of their vegetation at any time.

Gravel bars supporting pioneer stands of riverbottom forest may last but a year. Others are known to have supported riverbottom forest continuously for at least 250 years. In spite of this constancy of change the riverbottom forest floodplain is a very uniform habitat where macroclimate and substrate definitely determine the establishment of plant species, where soil moisture conditions are less rigorous than in the uplands and where the habitat can be quite uniform over wide geographical areas.

Riverbottom forest species are opportunists who take 194 advantage of pioneer sites offered, and survive for greater or lesser periods of time as successional trends and competition dictate. The number of plant species found in any stratum of the riverbottom forest community is a direct function of the number of species adapted to survive the climatic and soil regimes. For example, only three poplar species (Populus angustifolia, P. balsamifera and P. tremuloides) and their hybrid offspring can survive the edaphic- climatic conditions of the studied lengths of St. Mary River, Lee

Creek and Belly River and these are the tree stratum components.

There are many more species of herbaceous plants than woody ones on the northern great plains and a pioneer site such as a gravel bar is a prime target for colonization by many more herbaceous species than woody ones. In this study the riverbottom forest woody species to herbaceous species ratio was 44 to 250.

Plant survival in the floodplain habitat is considered from the standpoints of survival of the individual and survival of the species. The woody perennials survive as individuals for periods of time as short as one growing season or as long as 250 years. As species populations survival is insured because only small portions of the total riverbottom forest community area are destroyed each year and the annual re-establishment of species on pioneer sites off- sets population destruction.

The occurence of many perennial forbs, as well as annuals, on pioneer gravel bar sites is probably due as much to reseeding each year as to renewed growth from perennating buds. This is true on the many first terrace sites where annual high water results in erosion of the substrate and consequent removal of most overwintering organs 195 of herbaceous species, with the exception of more densely intertwined and matted root systems. Thus, abundant seed production is a principal species-survival mechanism, provided such seeds are not subject to damage by water. Abundant seed production is a characteristic of members of the most important plant families represented on pioneer gravel bar sites; Compositae, Leguminosae and Gramineae. While survival of the species population is of primary significance in terms of the vegetation, in terms of the survival of mature riverbottom forest stands, the life span of the individual is important. Hence the successional trend from gravel bar pioneer site to mature riverbottom forest stand has, as its parallel, a trend from herbaceous annuals or short-lived herbaceous perennials with high seed production toward longer-lived woody and herba~eous perennials.

The ephemeral nature of the riverbottom forest community is most favorable for establishment of any edaphically and climatically adapted species of plant capable of producing viable seed. Coloniz- ation of a new gravel bar by poplars may be dependent on the production and distribution of seed in the same year as gravel bar formation. Which poplar species or species hybrids that dominate the early stages in riverbottom forest development may be a function of which of them produced the. greatest or indeed any amount of seed during the year of colonization. Poplar species in southwest Alberta do not flower and produce seed every year. The viable period of cottonwood seeds in general may be inferred as being rather short.

This observation is based on the germination studies of Populus deltoides by Ware and Penfound (1949). Seeds of this species were produced in central Oklahoma about the first of May and seedlings 196 shortly thereafter. Experimental seeds from just-dehisced capsules had an 85% germination rate after one day in warm moist sand following two days of cold storage. A gradual and rapid fall-off in germination rate followed. No seeds germinated on or after the fourteenth day following collection. Seedlings of P. deltoides attained a height, in wild populations, of 50 cm or more by the end of the growing season and tap roots were 30 to 45 cm long.

Seeds of the southwest Alberta riverbottom forest community poplar dominants when produced are out of dehiscing capsules by mid-

June to mid-July just at the time when advantage can be taken of newly formed gravel bars, high water tables in gravels, and high precipitation rates. Survival is thus enhanced.

Poplar seedlings, having attained a height of 20 to 30 cm in two growing seasons, begin to assume a shrubby shape as the result of ground level lateral branching from the main stem. This shrubby shape persists for several years depending on the species and its exposure to sunlight and shade. Narrow-leaf cottonwood keeps the shrubby shape for as long as ten years. Balsam poplar and the AB hybrid tend toward cleaner lower trunks. When the lower lateral branches begin dying then usually one, occasionally two or three, i stems will assume apical dominance.

If poplars are to be successful in populating new gravel bars they must be able to survive complete inundation by flood waters several times during the years of advancement of the first terrace stage to the second. It is doubtful if seedling survival for all species of poplars under inundation is the same. If the 8-day survival with complete recovery reported for P. deltoides by Hosner 197

(1958) can be applied as a guideline, then forest species of southwest Alberta riverbottoms are reasonably safe from drowning since they are seldom continuously inundated for periods longer than four days. That native poplar species cannot endure long term flooding is evident in the headwaters of streams where beaver dams have caused flooding of stands of trees. Within a few weeks all poplars and spruces are dead. Willow species, however, seem able to survive under conditions of constant inundation of roots and lower stems.

While poplar species have an observed need for plentiful water supplies to their roots they are unable to tolerate long term root flooding. The rapid drainage and aeration of gravel soils prevents drowning.

Water availability to the roots of trees and shrubs in mature riverbottom forest is good to excellent throughout the growing season.

Spring flooding and rainfall re-charge of soil moisture are coincident with early season leaf-out and photosynthesis. Water seeping through the gravels from the upstream to downstream sides of a riverbottom forest stand, and high water tables, are evident from two observations:

(1) Seepage channels originating in low spots in the gravel (i.e.

"springs") were flowing or wet throughout most of the growing seasons of 1970, 1971 and 1972. During the summer of 1973 when precipitation and str~amflow were below normal these "springs" and seepage channels dried up by early August but no observable woody plant damage due to drouth was noticed. In the same summer many herbaceous species in the riverbottom forest failed to develop sufficiently to flower; (2)

During the course of obtaining tree trunk cores for age determinations it was commonly noted that as the stem core was removed from the 198 increment borer, varying amounts of tree sap would run out the end of the borer for varying lengths of time. This indicated plentiful supplies of water in these trees. Boring was done during 1971 and

1972 throughout the growing season and into autumn, even as late as mid-October after all leaves had dropped. At no time did sap fail to flow from the tree trunks. By autumn in the very dry year, 1973, sap flow from trees sampled with the inc~ement borer was very slow to nil.

Corings from the driest tree trunks were still wet enough to indicate that no extreme water stress had been placed on the trees.

The imperviousness of underlying bedrock formations allows water from the stre~ or from spring seepages to flow through and charge alluvial gravels without water draining into deeper underground reservoirs. A high water table is thereby promoted to the benefit of riverbottom forest species.

The river valleys originated during glacial and post-glacial times and the gravels supplied for riverbottom forest development are glacial in origin (Wyatt, 1939). The higher valley terraces are seldom influenced by the river and riverbottom forest does not develop on them. The deepening of the valley by stream erosion is a very slow process. River erosion destroys existing riverbottom communities and at the same time builds new sites available for connnunity colonization (Figure 21).

Quantitative data form the only adequate basis of any ecological study. That some species of trees are characteristically limited more or less to riverbottom floodplains (e.g. Populus spp.) is common knowledge, but the composition of a riverbottom forest is more complex than the superficial impression gained by casual observances 199

river erosion and deposition

prairie grassland / "third terrace"

new gravel bars

"first terrace" climax\ forest "second terrace" pioneer forest/ stand "first terrace"

Figure 21. Successional schema for the riverbottom forests of southwest Alberta, Canada.

indicates. It is only by such data as presented in density, dominance and frequency tables that any true conception can be reached regard- ing the relation of plants to their environment and the real composition of a forest stand. It was therefore deemed important to include in tree, shrub and herb strata analyses tables all of the species encountered in sampling. Generalizations based on data limited to dominants alone, or to selected strata only, may be incorrect or at least incomplete.

Investigators of floodplain forests in temperate North America

(Lee, 1945; Ware and Penfound, 1949; Shelford, 1954) have been in agreement that the pioneer stands of such forests include poplar species. Depending on the locale and the adaptability of the poplars to the environment, these are Populus deltoides, P. deltoides var. 200 occidentalis, !· balsamifera or!• angustifolia. Unlike the riverbottom forest of southwest Alberta, other riverbottom forests of more temperate climates are capable of successional development beyond the pioneer poplar stage to stages dominated by other species, such as maple, ash and elm. Maple, ash and elm species are not part of the native flora of southwest Alberta and riverbottom forests here go through a sere of poplar species only. These poplar-dominated stands are capable of self-perpetuation if the stability of the substrate permits. Therefore the successional pathway to the climax may be very short; the pioneer stage to a climatic-edaphic climax with the same species and perhaps even the same individuals as co-dominants.

Acer negundo, Fraxinus pennsylvanica, Lonicera tartarica,

Populus deltoides var. occidentalis (P. sargentii) and some exotic poplar hybrids have been introduced into southwest Alberta by man.

negundo and Lonicera tartarica have become established as small naturalized populations on Lee Creek near Cardston. In spite of these introductions and the success of the individuals no exotic species of woody plants have become important members of the southwest Alberta riverbottom forest community. This is true despite their importance in floodplain forests of other regions.

It is doubtful if any of the 294 species of plants found in this study are truly riverbottom forest endemics. Even the dominant species of the four different strata are not limited to the riverbottom forest community. Each of the poplar species can be found in some other habitat, from abandoned gravel pits to home shelterbelts.

River birch and dogwood can be found on moist sandy soil sites in other plant communities and snowberry, silverberry, rose and 201 serviceberry are likewise scattered across the plains and coulees of the grasslands and aspen parkland. Four of the nine herbaceous stratum dominants are introduced exotics found in a wide variety of other habitats. Of the five native herbaceous dominants not one is truly endemic to the southwest Alberta riverbottom forest conununity.

The riverbottom forest poplar dominants are derived partly from the adjacent forest regions and partly from the riverbottom forests on other streams to the south, east and north. Balsam poplar

(Populus balsamifera trichocarpa) has followed the streams down through the foothills from Rocky Mountain populations. Narrow-leaf cottonwood (Populus angustifolia) seems to have spread from stream to stream along the edge of the foothill zone from the south (Brayshaw,

1965). Narrow-leaf cottonwood has not extended its range into the transition and montane for~sts of the lower mountain slopes, nor has it extended its range more than casually east and north beyond

Lethbridge.

Narrow-leaf cottonwood - balsam poplar hybrids have their population centers within the areas of overlap of the parent species.

Brayshaw (1965) found scattered AB hybrids in eastern Alberta well beyond the distribution limits of the parent species.

Plains cottonwood _(Populus deltoides occidentalis, = P. sargentii), a most important eastern and northern species of floodplain forests, has been unable to colonize the valleys of St. Mary

River and Lee Creek. Its range does extend up Belly River to near

Monarch. Quaking aspen (Populus tremuloides) is a ubiquitous species, finding any mountain and foothills climate to its liking, requiring 202 only adequate soil moisture and persisting in small stands on the better soils along river valleys where conditions are similar to those of its population centers in the Rocky Mountain foothills and the northern half of Alberta.

Superficial estimates of poplar species in pioneer stands indicated that seedlings of narrow-leaf poplar, balsam poplar and AB hybrids were present. Colonization of new gravel bars does not seem to be the prerogative of any one poplar species, but this is only a tentative conclusion and must be verified through further study. In the mature riverbottom forest conununity a comparison of importance values for the three poplar species dominants shows that there is little difference between those values for mature trees

(narrow-leaf cottonwood 94.5, balsam poplar 89.9, AB hybrid 110.8) and for tree reproduction (narrow-leaf cottonwood 118.9, balsam poplar 90.7, AB hybrid 79.1). The differences in importance values for trees during early stage~ of riverbottom forest development can best be accounted for by considering that such differences are the product of the random colonization of new sites by available seeds.

Succession in mature stands seems to favor one poplar slightly, the

AB hybrid. A question arises;_ is the importance of the AB hybrid the result of bias in sampling? The greater relative and absolute values assigned to the AB hybrid should not be thought of as the result of too stringent name assignments to the pure species during data collection. Rather liberal terms were used in this study in defining narrow-leaf cottonwood and balsam poplar in stand analyses. It is hoped that bias was overcome by considering that any tree, of the 203 three types in question, examined in sampling had a 33% chance of being designated narrow-leaf cottonwood, a 33% chance of being balsam poplar, or a 33% chance of being an AB hybrid.

At the beginning of this study a preconceived opinion of the author's was that narrow-leaf cottonwood was unable to compete with other poplar species when forest maturity was reached. If this hypothesis was true, then it should be expected that narrow-leaf cottonwood importance values would be very low in sampled mature stands of riverbottom forest. To the contrary, in each of the ten study stands this species was a very important constituent of the mature tree stratum. Its importance value average of all stands,

94.5, made it more important than balsam poplar (I.V. 89.9) and only slightly less important than the AB hybrid (I.V. 110.8). In its ability to reproduce and perpetuate itself within the community narrow-leaf cottonwood had the highest average importance value

(118.9) in comparison to balsam poplar (I.V. 90.7) and the AB hybrid (I.V. 79~1).

As for absolute values, narrow-leaf cottonwood ranked intermediate in density (91.5 trees per hectare) between balsam poplar

(88.9 trees per hectare) and the AB hybrid (96.9 trees per hectare).

Absolute density values in tree reproduction for all stands put narrowleaf cottonwood well ahead (113.3 sapling~ per hectare~ of balsam poplar (81.5 sap~ings per hectare) and the AB hybrid (65.0 saplings per hectare).

The relative success of the AB hybrid in the mature tree stratum may be due to its greater pioneer site colonization ability and its greater average longevity rather than to its reproductive 204 ability in the mature forest.

The growth in diameter·of poplars on the three study streams is not nearly so rapid as the growth of other poplar species in better climates. Shelford's (1954) report of Populus deltoides on the Mississippi River floodplain growing to a diameter of 60 centimeters (24 inches) in 20 years is in great contrast to the 13 and 16 centimeter (5 and 6 inch) diameters achieved by St. Mary River, Lee

Creek and Belly River poplars in the same span of time.

Mature riverbottom forest stands that have been under a heavy grazing regime, by sheep in particular, are quite open and one can walk through them with only minor deviations in his course. Shrubs occur singly or in small patches and between. these are low-growing herbaceous species (Figure 11). This "English Park" appearance contrasts with other stands grazed _lightly or not at all. These can be most difficult to walk through. Rose thickets, silverberry thickets, dogwood clumps and snowberry patches can be so dense, continuous and high as to be impenetrable to all but the most determined person.

No correlation could be found between the average age of trees in a stand and average penetrometer readings for stands.

Alluvium buildup is a product of the number of over-bank floods that have occurred during the life of the terrace and these vary from stand to stand.

Observations of exposed root systems and undercut and fallen trees show that lateral stream migration is a major factor with which floodplain plants must contend (Lindsay et al, 1961). It is due to this erosion on the one side and deposition on the other that 205 the floodplain owes its existence. The proportion of over-bank deposits is very small compared with channel deposits.

Island formation on St. Mary River, Lee Creek and Belly River is rare in contrast to its importance on other streams (Lindsay~ al,

1961). Islands rarely form in the central part of a stream channel.

Flood season high water running down overflow channels in the forest may cause blocks of riverbottom forest to be isolated temporarily.

Islands may be formed when channel alteration occurs as the result of stream departure from the current channel to a new or older channel.

Cardwell's Island became a true island when the St. Mary River shifted part of its flow to a long abandoned channel during the flood of 1964. Deepening of the new channel has gradually reduced flow in the pre-1964 channel and island status may soon be lost.

Few standing dead trees of any species are found in mature riverbottom forest. Trees do die, but they quickly rot at the base and soon topple with a good deal of wind help. On the ground the tree rapidly disintegrates and is recycled. The longest lasting are dead stem stubs, usually attached to the living tree by overgrowing annual rings. These stubs provide nest sites for flickers and subsequently for other bird species. Occasional hives of honey bees are to be found in the decayed interiors of otherwise living trees.

Fires of accidental or intentional origin have burned out the lower trunk center of some large poplars without causing the death of the tree.

In spite of the quantities of tree and shrub leaves and other herbaceous debris falling to the ground each autumn, only shallow layers of organic material have accumulated on the surface of mature 206 riverbottom forest soils. Autumn winds blow the leaves away or pile them up in sheltered spots. Saprophytic reduction is rapid and by leaf-out of the next spring the previous year's organic debris is little in evidence.

Mechanical damage to standing trees during over-bank flooding appeared to be minimal, based on a survey of trees in stands flooded . in 1964. Trees torn away by lateral corrosion are badly abraded by transported and bottom gravels as they are tumbled downstream.

Over-bank floods with slower moving water transport only the finer sands and silts that do not damage tree stems. Ice blocks were frequently pushed or floated out on to first terrace pioneer sites during unusual Viriter and normal early spring break up. Hydraulic pressure exerted from below by increased stream.flow will break heavy ice into cakes and these float downstream until the receding water leaves them stranded on gravel bars. The general and unsupported hypothesis is that ice does not cause appreciable damage to pioneer or mature riverbottom forest stands.

Soils under riverbottom forest stands are gravelly and top- soil layers so thin that clearing of riverbottom forest by man for farming has never been an agricultural practice. Third and higher grassland terraces Vi.th good soil are sufficiently removed from flood danger to make farming them no more hazardous than farming the surrounding prairies. Loss of third and higher terrace farm lands by the lateral erosional action of the river is localized and while of great concern to the individual landowner is not a widespread problem in southwest Alberta. It is not a common practice to construct levees or diversions to protect farmland along the streams. 207

Early autumn and late spring frost pockets on calm nights in the river valleys may decrease gardening success there and have some harmful effect on the native flora, but field crop plants, mostly wheat, oats, barley, forage legumes and grass hay, are seldom frost damaged. Frost damage to some of the native herbaceous species of the riverbottom forest was noted in early May of 1971. The effect of prairie wildfire, long known to be devastating to Indian and settler alike, on riverbottom forest is unknown.

Various accounts of prairie wildfires in southwest Alberta settlement days tell of the importance of creeks and rivers in stopping the fire but do not mention what effect the fire had on the trees along these streams. Poplars are not notably fire resistant species and the probability of damage or death to them is great. The high percentage of bare ground under the forest probably afforded some fire protection.

Some poplars, especially narrow-leaf cottonwood, in the 16 to 25 cm diameter class have an "apron" of dry dead branches on the lower part of the stem, usually above 1.5 meters from the ground, and this will burn readily and fiercely killing the tree with the heat. Intentional burning of riverbottom forest is almost impossible to carry out. In the autumn of 1972 the landowner set fire intentionally to Site 6 -

Slaughter Hole hoping to b~rn out some piles of flood debris and clear out the heavy underbrush. The fire very nearly refused to burn at all; the driftwood piles were too full of dirt and decaying leaves, and the green brush would not burn. The burning attempt was a failure. Less than 0.5 hectares of the riverbottom forest actually had fire through it. A few poplars were heat-killed. By the summer of 1973 root suckering had brought the brush back strongly and herbaceous species 208 were common.

Riverbottom forest stands grazed by cattle tend to remain heavily brushed. Grass forage is minimal and use is made of the forest for shade during hotter summer days. When flies and mosquitoes become intolerable the cattle move to open windy areas on the grassland where biting insects are less apt to be bothersome. Sheep have been effective in reducing shrub densities and promoting grass cover in several riverbottom forest stands (Figures

11 and 12). Any factor, such as sheep grazing, that can reduce tree reproduction to nil will promote the development of a grassland community which assumes dominance as the forest trees reach maturity and die (Figure 21). SUMMARYAND CONCLUSIONS

Ten stands in the riverbottom forest community of St. Mary

River, Lee Creek and Belly River in southwest Alberta, Canada were analyzed for plant species composition during the period 1970 -

1973. Four vegetational strata in the community are recognized;

(1) the tree canopy and its reproduction, (2) clumped shrubs, (3) thicket shrubs, and (4) herbaceous understory. Vegetational analysis methods were (1) the point-centered quarter method for trees, tree reproduction and clumped shrubs; (2) the line intercept method for thicket shrubs; and (3) the quadrat method for herbaceous vegetation and unoccupied space. Data were summarized and reported in absolute terms (density, dominance) and relative terms (density, dominance, frequency, importance value). Similarities between the ten stands outweighed the dissimilarities and all ten stands were deemed to be parts of a southwest Alberta riverbottom forest community. Dominant species and their importance value, based on a maximum possible of

300, in the four vegetational strata of the mature riverbottom forest community were: (1) trees - Populus X balsamifera I.V. 110.8, P. angustifolia I.V. 94.5, P. balsamifera I.V. 89.9; tree reproduction -

P. angustifolia I.V. 118.9, !_. balsamifera I.V. 90.7, P. X balsamifera

I.V. 79.1; (2) clumped shrubs - Betula occidentalis I.V. 171.8,

Cornus stolonifera I.V. 72.1; (3) thicket shrubs - Elaeagnus commutata

i I.V. 80.5, Symphoricarpos occidentalis I.V. 59.0, Rosa woodsii I.V.

55.3, Amelanchier alnifolia I.V. 30.9; (4) herbs - pratensis I.V. 210

41.9, Medicago lupulina I.V. 26.3, Poa compressa I.V. 12.1,

Chrysopsis villosa I.V. 11.1, Solidago mollis I.V. 10.6, Phleum pratense I.V. 10.4, O?tytropis viscida I.V. 10.1, Aster laevis I.V.

9.3, Fragaria virginiana I.V. 7.5. All of the woody plant dominants and five of the nine herb dominants are species native to southwest

Alberta.

Succession in the southwest Alberta riverbottom forest community follows an interwoven pattern of (1) new gravel bar, the first terrace, formed by river deposition; (2) pioneer riverbottom forest on the first terrace gravel bar floristically composed of herb species and poplar species' seedlings; (3) maturing riverbottom forest stands on first and second terraces with poplar saplings, clumped and thicket shrub invaders and herbs; and (4) poplar- dominated climax stands capable of self-perpetuation, with mature clumped and thicket shrubs and perennial herbs. Any stage in succession may be destroyed during progressive lateral erosion by the river and this is the usual fate of the climax forest.

Unoccupied space (bare ground and litter) accounted for 66.2%. of the total herb stratum area.

Riverbottom forest soils range from gravel (61.1% rocks greater than 0.5 centimeters diameter and 38.9% sand) to sandy loams above a gravel base of unknown thickness. The sandy loam surface layer is the result of a build-up of water-borne particles deposited during infrequent over-bank flooding. Mean penetration of the soil by the penetrometer averaged 0.4 decimeters on gravel bar pioneer forest sites and 2.5 decimeters in mature forest sites. The pH values averaged 8.0 on gravel bar pioneer sites, 7.7 in mature forest 211 soils and 7.6 in neighboring fescue prairie grassland soils. Soil soluble salts averaged 176 parts per million on gravel bars, 458 ppm in mature forest soils and 409 ppm in the neighboring grassland soils.

The average diameters and ages of the poplar dominants in mature riverbottom forest stands were (1) Populus X balsamifera 26.2 cm, 45 years; (2) P. balsamifera 21.8 cm, 38 years; and (3) P. angustifolia 20.8 cm, 36 years. Maximumage for any single tree of the dominant poplar species was (1) !'._. X balsamifera 250 years, (2)

P. angustifolia 160 years, and (3) P. balsamifera 155 years. Height of the mature poplar dominants ranged from 15 to 22 meters.

The climate of southwest Alberta is typically continental and cool, with warm summers and cold winters. Average annual precipitation is 45.8 cm (18.04 in.) with 65% of the total falling during the growing season.

Development of riverbottom forest is conditional on climate and substrate. The climate determines the species that are able to survive in southwest Alberta and the continually forming gravel bars of the streams provide the necessary substrate. Development of the forest is correlated with May-June flooding and gravel bar formation;

May-June precipitation; June-July poplar seed production, dispersal and germination; and a high water table in the gravel substrate. The gravels are of mountain and continental glacial origin and overlie strata of Upper Cretaceous and Tertiary ages.

The riverbottom forest flora is composed of 294 species of vascular plants in 165 genera representing 50 families. Of these

294 species, 44 are woody plant species and 250 are herbs. The 212

plant families contributing most to the riverbottom forest community

flora are Compositae, Leguminosae, Gramineae, Rosaceae, Salicaceae,

and Umbelliferae. These six families account for 76 (46%) of the

genera and 172 (58%) of the species. One species new to Alberta was found. Canada Plum (Prunus

nigra Ait.) is now known from Lee Creek, 0.5 kilometers southwest of

Cardston, Alberta. Range extensio~& for 13 species were provided by

this study. No species of plant is truly endemic to the riverbottom

forest on southwest Alberta. Plant species in the riverbottom forest

community are opportunists able to take advantage of the continuing

availability of new gravel bars for colonization.

The riverbottom forest community of southwest Alberta has

little economic value. Livestock grazing and shelter are the major uses and recreation is a minor use. This counnunity provides some wildlife habitat, especially for white-tailed and mule deer.

Fire is unimportant in riverbottom forest dynamics at the present time. The greatest altering force of riverbottom forest

stands is water erosion.

The riverbottom forest community of St. Mary River, Lee Creek

and Belly River in southwest Alberta, Canada is a unique ecological

entity characterized by po~lar species that have their major Alberta

distribution along these streams. LITERATURECITED

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Robert Keith Shaw

Department of Botany and Range Science

Ph.D. Degree, August 1974

ABSTRACT

The riverbottom forest community of St. Mary River, Lee Creek and Belly River in southwest Alberta, Canada is a unique ecological entity characterized by poplar species having their major Alberta distribution along these streams. Stands in the community are dominated by three tree species, six shrub species and nine herb species. Establishment of the community is dependent on climate and substrate; destruction is the result of progressive lateral streamflow erosion. Soils are sandy loams above gravel, with pH values of 7.7 to 8.0 and soluble salt concentrations of 176 to 458 parts per million. Trees in mature stands averaged 23.0 centimeters in diameter and 40 years in age; maximum tree age was 250 years. The vascular flora consists of 294 species of which 44 are woody and 250 herbaceous. One species (Prunus nigra Ait.) new to Alberta and range extensions for 13 species are cited, There are no true community endemic species. Recreational and livestock raising uses are present. community modifiers. Fire is not important in current forest dynamics. •