An Ecological and Taxonomic Survey of the Spermatophytes of Jasper Ridge

AN ECOLOGICAL AND TAXONOMIC SURVEY OF THE SPERMATOPHYTES OF

JASPER RIDG-E

A THESIS SUBMITTED TO THE SCHOOL OF BIOLOGICAL SCIENCES (NATURAL HISTORY MUSEUM) AND TEE COMMITTEE ON GRADUATE STUDY OF TEE LELAND STANFORD JUNIOR UNIVERSITY IN PARTIAL FULFILLMENT OF TEE REQUIREMENTS FOh THE DEGREE OF MASTER OF ARTS

By John Carter Moeur December, 1947 Approved for the Department

Approved for the Committee on Graduate Study TABLiJ OF CONTENTS

Page

I. Introduction 1 II. Survey Methods and Limitations 3 III. Description of Jasper Ridge A. Topography and General Description 6 B. Geology 8

C. Soil 10

D. Rainfall, Temperature, and other Climatic Conditions 13 E. Vegetative Zones 19 IV. Plant Formations A. Time of Flowering 20

B. Forest 23 C. Chaparral 28 D. Grasslands . 31 V. Ecological Interpretations 35

VI. Annotated List of Sperroatophytes Pound on Jasper Ridge 38

VII. Summary 77

VIII. Conclusion 79

IX. Bibliography 81 ILLUSTRATIONS

TABLES

Table No. Page I. Searsville Lake Rainfall 14 II. Comparative Rainfall Records 15 III.- Number of Spermatophytes Beginning Anthesis in Each Month on Jasper Ridge _ 22

PLATES

Plate No. After Page I. Searsville Lake 6 II. Map of the Geological Formations of Jasper Ridge 8 III. Map of the Soils of Jasper Ridge 11 IV. Map of the Vegetative Zones of Jasper Ridge 20 V. Heavily Wooded Forest on North Slope 26 VI. Chaparral Area Near Searsville Lake 29 VII. Grassland, With Scattered Specimens of Quercus a^rifolia and Quercus lobata 51 The general purpose of this survey of the seed- bearing plants of Jasper Ridge has been to collect and tabulate, as nearly as possible, specimens of all the spermatophytes growing in the area, to note the chief ecological factors which are responsible for the vegetational aspect of the region, and to present these data in such a way as to account for the type of plant life which occurs in each -of the distinct plant zones found on the ridge.

Jasper Ridge was selected as the locale for this survey both because of its proximity to the Stanford campus, and because there occur within its limits the three typical types of vegetational zones which are representative of the Cosst Ranges in general. These are the forest, chaparral, and grassland. The flora of each zone was carefully studied, especially in regard to the number and types of species, abundance of the main con- stituents, and the flowering and fruiting periods.of the plants.

I want to express my appreciation to the members of the staff of the Dudley Herbarium of Stanford University, particularly Dr. Ira L. Wiggins and Mrs. Roxsna S. Ferris, for their valuable assistance in identifying plants from the ridge. I wish to thank Dr. Rimo Baclgalupi also for his aid in the herbarium and in the field work. II SURVEY METHODS AND LIMITATIONS

The survey was conducted during the period between March and December, 1947. Collecting trips were mede to the ridge at least once a we^k during the spring and early summer months when the majority of the plants were at the height of their blooming season. Later during the summer, and in the fall, collections were made on an average of about once every two weeks, since at that time relatively few plants were in bloom on the ridge. On each collecting trip, an attempt was. made to obtain specimens of each species found in bloom in each of the three representative life zones, with the exception of a few pi exits such as Anagallis arvensis, Brassica campestris, Raphanus sativus, and the different species of the genus Erocium, which were found blooming to some extent almost throughout the entire period of the survey. Rather than make many unneccessary collections/ specimens of plants such as these were obtained only during the peak of their blooming season, and during the rest of the survey were merely noted. I attempted to cover the ridge as thoroughly and systematically as possible on each trip. Each species was collected when first discovered in bloom, and in many cases, again when the first ripe fruits were found. Each specimen was classified as to the area in which it was found, and the date. I made no attempt to collect specimens from Searsville Lake itself. Bowever,.several species were obtained from the immediate shores of the lake, particularly in the summer and fall, when the water had receded considerably. A few of the plants were classified in the field, but in the main the determinations were made in the labo-

ratory,r where they were compared with authentic specimens / deposited in the Dudley Herbarium. Three taxonomic works were used in the identification of the specimens; they

were Dr. '.Villis Linn Jepson1 s Manual ojT the Flov-erinp; Plants of California (8), Dr. A. S. Hitchcock's Manual

9JL ihe Itrj^sejs of th_e United .StatejJ (7) , and Dr. LeRoy

Abrams' IjJLustratjed Flpr§ of the Pacific States, Vols. I and II (1 & 2). In the denser stands of chaparral there are areas which are to all practical purposes impenetrable and in such cases collections were made only around the margins of the shrubby communities.

Unfortunately I was able to carry on my work only

from the middle of March through the first of December and in all probability, a few plants whose blooming seasons occur in February and early March were entirely missed. However, in several cases, isolated and late- flowering specimens of these early plants were found and identified. This, in part, made up for the regrettable gaps in the field work. Ill DESCRIPTION OP JASPER RIDGE

A. Topography and General Description - Jasper Ridge lies in the Santa Cruz Quadrangle of the Coast Ranges in San Mateo County, California. It is in the higher foothills of the Ssnta Cruz Range, which is one of the two main divisions of the Coast Range, standing between the broad Santa Clara Valley to the

east and. the Pacific Ocean to the west. The Ssnta Cruz Mountains are characterized by well rounded hills and evenly sloping valleys. The hillsides are usually covered with a fairly deep coating of soil, and cliffs are rare. On the extreme northern side of Jasper Ridge there is a small cliff rising rather abruptly from San Francisquito Creek, but in the main the topography follows the general pattern of the Santa Cruz Range. Another feature of the ridge which is again characteristic of the Santa Cruz Mountains is the relative steepness of many of the soil-covered hillsides, slopes of 30° to 55° being common. The streams on the northeast side of the main water- shed flo?/ into the San Francisco Bay; on the west directly into the Pacific Ocean. The basins of the streams on the eastern side are smaller than those on the west, and of these the largest is San Francisquito Creek with an area of 37 square miles in its drainage basin. Jasper Ridge PLATE I

SKARSVILLi LAKb) RIDGE IN B is situated in this basin. The streams in this basin and in others on the eastern side of the Santa Cruz Mountains are perennial only in the upper portions. In

the summer and autumn they disappear soon after they emerge from the foothills upon the plain, the water enter- ing the gravels which underlie the Santa Clara Valley. Where the streams enter the plain of the valley, they are

characterized by broad low alluvial fans. San Francis-

quit o Creek flows along the crest of a ridge that has been built by its alluvial deposits. Jasper Ridge itself is almost surrounded by the valleys of three creeks, two of which, Los Trances and Corte de Madera, are tributaries of the main creek, San

Prancisquito, which borders the ridge along the north and northeast. To the east is the valley of Los Trancos Creek and to the south and southwest that of Corte de Madera Creek, which runs into Searsville Lake, formed by a dam across San Prancisquito Creek. The portion of the ridge which was studied is approximately three and one quarter miles long as measured northwest by southeast, and a little over two miles wide north-

east by southwest. The average height of the top of the ridge is 600 feet, although the extremes of altitude are a little over 200 feet at the most northwesternly point, and 800 feet at the highest point, which is located in the southeastern part. Searsville Lake is at an elevation of 518 feet and the ricige rises abruptly immediately to

the east of it in a series of steeply sloping soil- covered hillsides. With the exception of the previously mentioned cliff on the northern side, the topography of the ridge is one of rather steep hillsides leveling out into valleys and grasslands, and intersected at many places by steep ravines down which streams flow during the rainy season to feed into the lake or one of the surrounding creeks.

B.. Geology

The information on the geological features of

Jasper Ridge was obtained from the Santa Cruz Folio of the U. S. Geological Survey (4) ana the different formations are shown on a map (Plate II) which was copied from that work. The most extensive geological formation of the ridge is the Chico Formation, which is a sedimentary deposit of the Upper Cretaceous. It extends in a broad band from the northern limits of the ridge, along San Prancisquito Creek, to Los Trancos Creek on the southeastern border, where it occupies the major portion of that part of the ridge. This rock, which ia a heavy-bedded sandstone and conglomerate, with a small amount of shale, weathers into a. uniform coarse yellow sand. In most places the layer of residual soil is quite thin, but on a few level spots MAP OF THE

GEOLOGICAL FORMATIONS OF JASPER RIDGE

LEGEND

SANTA CLARA FORMATION FRANCISCAN FORMATION

CHICO FORMATIOH PURISSIMA FORMATION

SERPENTINE PLATE H there is a greater depth. The sand, merges gradually

into the undecomposed rock, which is practically intact at a maxim-urn depth of three feet or a little more. On steep hillsides the soil is irregular in depth, with rock outcrops alternating with sandpockets. Along the northeast part of the ridge, and from there to the confluence of San Prancisquito and Los Trancos Creeks, is found a deposit of the Purissima Formation, which is a conformable series of sediments of the Upper Miocene and much of the Pliocene. This rock is composed in the main of heavy conglomerate, sandstone, and shale which is in part diatomaceous. 4^large part of this area is under cultivation and is not actually a part of the ridge proper. There are two areas of the Franciscan Formation of considerable extent, one of them nearly surrounding the lake and extending eastward from it in a wedge-shaped section, and the other arising at the extreme southeastern part of the ridge. This formation, which is the oldest of all of those found on the ridge, is composed of a series of metamorphosed sedimentary rocks of the Jurassic. It consists of sandstone, shale, and some conglomerate, with lenticular masses of limestone, jasper, chert, schist, and greenstone.

The most recent geological formation found on the ridge is that of the Santa Clara Formation, which is a 10 sedimentary deposit of the late Pliocene, merging with recent alluvium* It consists of gravel, sand, and clay, chiefly of fresh water origin, and extends in a broad "band along the southern and southwestern boundaries of the ridge. Between the Franciscan Formation near the lake and the Chico Formation on the northern edge of the ridge is a long slender outcrop of serpentine. It is an igneous deposit of the Pre-Tertiary, consisting of altered intrusive masses and dikes of basic rocks.

C. Soil

Although apparently the only soil which influences plant growthto any appreciable extent is that occurring in the narrow strip of serpentine, brief mention•should be m&de of the other types found on the ridge. The map

(Plate III) showing the various types was redrawn from the U. S. Department of Agriculture's Hejcojnn^^^sa.n.ce Soil Survey ojf the San F^aricj.jjcjq Bav Region, California (5) . By far the most common soils of Jasper Ridge are those of the Altemont loam and clay loam group, which cover almost the entire area of the Chico and Franciscan Formations These soils are residual from sandstones and shales and to a lesser extent from conglomerates, and weather into the rather cosrse yellowish sand or loam previously described.

On the southeastern portion of the ridge there is a section 11 of the rough broken phase of the-Altamont loams and clay loams, which Is similar to the above except that it is stonier and contains a great many more rocks and other undifferentiated bodies. The drainage of these types of soils is always good and over areas of steep topography r usually excessive.

The soil derived from the Purissima Formation at the northeastern section of the ridge is of the Altamont adobe type, consisting of a brownish friable clay loam or clay, having the true adobe structure. A fern cobbles, shale fragments or angular pieces of other rocks are sometimes found on the surface or scattered through the soil, but these are of restricted distribution and are usually confined to areas of steeper topography or shallov/ soil. Drainage is everywhere good and sometimes excessive in areas of shallow soil on the steeper slopes.

Along San Frsncisquito Creek, at the northern edge of the ridge, is a strip of silt loam of the Yolo loam type. This is an alluvial soil, derived largely from i materials washed from sedimentary rocks. It is a brownish friable silt loam which has good drainage due largely to the free and open character of the subsoil. In the eastern part of the ridge along Los Trancos Greek there is a section of soil of the Diablo type (undifferentiated) , which is quite similar to the Altamont loams which surround it. Like the Altamont, it is derived MAP OF THE. SOILS OP JASPEH RIDGE

LEGEND

ALTAMONT LOAM AND CLAY LOAM ALTALONT ADOBE

ALTAMONT LOAM MD CliAY LOAM (ROUGH BROKEN PHASE) PLEASANTON LOAM

STONY. SOIL (UWDIPPBRENTIATED) YOLO LOAM

SITES LOAM AND CLAY LOAM DIABLO (UNDIPPERENTIATED) ?LAT£ UL 12

from shales and sandstones and differs only in having a more pronounced adobe stracture and a greater water

retaining capacity. Soil of the Sites loam type is found at the southeastern tip of the ridge, in the area of the Franciscan

Formstion. It is a reddish-brown, rather friable loam, fairly gravelly, and is derived from metamorphosed sedi-

mentary rocks. It offers thorough if not excessive drainage.

The soil of the Santa Clara Formation along the

southern edge of the ridge is of the Pleasanton gravelly

loam type. Derived from unconsolidated sediments -which

have been modified by weathering and erosion, it is a

brownish loam containing waterworn gravel and some quartz. Drainage is generally sufficient, except for short periods following long-continued rains, when the soil may become thoroughly saturated. The strip of serpentine offers the only type of soil found on the ridge which is decidedly different. Here, instead of the sands or sandy loams occurring throughout most of the rest of the ridge, is found an undifferentiated

stony soil which is the shallow, residual product from the disintegration and weathering of igneous rocks, mainly serpentine. This area is characterized by its typically shallow soil covering ano very stony surface. There is little or no subsoil, drainage is excessive, and the area 15

has a very low organic-matter content. Certain plants occur here which are found nowhere else throughout the ridge, while elsewhere there is apparently no differ- entiation due to soil factors alone.

D. Rainfall, Temperature,

and Other Climatic Conditions

In general, Jasper Ridge is characterized by comparatively wet winters, followed by long, dry summers, during which time there may be little or no rain for periods of three to four or occasionally even five months. This is a climate which is characteristic of the chaparral type of vegetation, and originally chaparral was the dominant vegetational form throughout the ridge. In recent times, however, it has been cleared out to a great extent. The rainfall records for the ridge are very meagre and those few ?/hich were obtainable were not considered satisfactory enough to warrant their use as a basis upon which to draw any definite conclusion. Records have been kept, however, at Searsville Lake for a period, of fifteen years. Although these records in all probability do not coincide exactly with the amount of rainfall on the ridge itself, due to the difference in altitude between the two areas, they are nevertheless a fairly close approximation of the precipitation on the ridge. (The records for the 14 TABLE i Searsville Lake Rainfall (From Record of Ernst Ivi. Brancsten) 1932 . 1953 1934 1955 1936 -53 -54 -35 -56 -'•:? July August . 50 September .95 .23 October .41 r 1.90 1.03 .78 • *-') C8J November .80 5.09 .46 December 4.57 6.92 3.68 5.46 6 .85 January 9.09 1.32 9.06 7.56 7.06 February 1.20 5.46 1.29 11.48 7.53 March 3.36 5.90 1.20 9.40 April .25 .67 5.83 1.72 .90 May 1.86 .65 .90 June .55 .16 -

Totals 21 . 54 17.47 32.83 28.25 52.12

1937 1938 1959 1940 1941 -38 -39 -40 -41 -42 July August .20 I September .45 .20 ' October .83 1.50 1.11 1.40 .98 1 November 4.68 1.81 .SO .70 1.76 | December 7.68 1.18 1.28 9.45 9.31 January 5.16 6.69 11.49 8.29 6.65 I February 11.25 5.45 11.38 7.89 4 . 38 March 6.49 2.54 6.50 5 . 5.6 4.25 i April 2.30 .93 .55 3.49 4.80 { May 1.65 .59 1.07 2.82 r June Totals 38.39 19.75 34.15 38.05 34.95 1 3

Tj 1942 1945 1944 1945 1946 j -43 -44 -45 -46 -47 1

July .07 1 August 1 September .20 .07 \, October .83 1.10 2.50 3.65 .15 I November 7.00 .94 5.70 5.47 - December 3.89 2.57 3.37 5.12 ? January 8.80 4.12 .64 2.17 >• February 2.15 6.64 7.05 4.89 ' Inarch 4.12 1.22 5.54 .40 ? April 1.95 2.22 .60 .40 May 1.15 .90 .10 June Totals 28.92 19.96 24.28 16.84 15

season of 1945-46 are missing, with the exception of the month of October) . Prom the preceding table, it appears that the winter months of December, January, February and March are the ones of heaviest precipitation, with the rains then slacking off appreciably in April and May, occurring little or not at all during the summer, and beginning again in the late fall. A comparison of the annual precipitation recorded at various adjacent areas other than Searsville Lske may help to give even a better indication of the rainfall at Jasper Ridge. Records from the Palo Alto (elevation 58 feet) and Black Mountain (elevation 2700 feet) stations are listed below, together with those from Searsville Lake (elevation 518 feet) . (Records were obtainable from Black Mountain only for the years 19415-44 and 1944-45, and are probably not statistically significant).

TABLE II Comparative Rainfall Records

Year Palo Alto Searsville Lake Black Mountain 1941-42 19.54 54.95 1942-45 17.81 30.92 1943-44 11.85 19.56 50.93 1944-45 15.16 24.28 29.23

Averages 16.04 27.45 50.08 If ' 16 ? That there is a decided drop in rainfall as one goes east from the mountains toward the bay, from higher ele- vations to lower ones, is evidenced by the above table. Accordingly, it con be assumed that Jasper Ridge, whose elevation is between that of Searsville Lake and Black Mountain, has an annual rainfall somewhere between the ones recorded at those stations, probably about 28.5 inches per year.

Temperature records for the ridge, both soil and

atmospherip, are even scantier than those for rainfall. About the only ones .to be found are those in Dr. William S. Cooper's paper, The Broad-Sclerophyll Vegetation of California (6), which were taken during the years 1913-14. Reference was also made to the data contained in Margaret Alice Barry1 s A Ploristic and Geologic Study _of Goal Mine Ridge (3). The area studied in her work is only a few miles distant from Jasper Ridge and the climatic conditions of both areas may be assumed to be similar. Apparently atmospheric temperature has little if any control over the types of vegetation which are found on

either the northern or southern slopes of the ridge. Dr.

Cooper took simultaneous readings in both the chaparral of the southern slopes and the oak forests of the northern ones and found no appreciable temperature differences. Miss Barry, in fact, found that during the hot months of the year, the north slope readings were often a few degrees 17 higher than those on the south. She attributed this to

the fact that the northern slopes were cut off by the crest

of the ridge from the ocean breeze which helps to cool the

southern side. In general, the atmospheric temperature of Jasper

Ridge ranp:es from an average maximum of about 85° F. and an average minimum of about 55° P. during the hot summer months to an average maximum of about 60 P. and an average minimum of around 55° P. during January and February, whien are the coldest months of the year. Freezing temperatures occur several times during the winter, and a low of o 12 P. has been recorded. The highest temperature ever recorded on the ridge was 103 P. There is a noticeable variation in the soil temperatures of the northern and southern slopes of the ridge during the dry season. At that time the maximum soil temperature of the southern slopes often equals or even surpasses the atmospheric temperature, whereas the northern slopes have a maximum soil temperature which generally does not range much above 70° P. The minimum temperatures of both slopes are fairly equal, usually ranging from 60° P. to 70° P. With the coming of the wet season the soils of both slopes exhibit nearly identical temperatures, 55° P. being the average maximum temperature during January and

February, and 45° P. the average minimum. Other climatic factors which might affect plant growth on the ridge are fog, light, and wind. It is probable that 18

Jasper Kidge has a smaller total of fog than either the valley or the mountains. The true ocean fogs rarely reach it, and the "bay" or !ltuletf fogs, which are frequent during

the forenoon in the lowlands, do not ordinarily extend so far from the bay. The average midday temperature of the ridge is probably higher than that in the valley because of the proximity of the bay to the latter, and because of this high temperature and the relative absence of fog, there is a high evaporation-rate. The evidence of the vegetation is that there is little climatic difference between the ridge and the valley; this is due at least in part to the fact that the greater rainfall of the ricge is neutralized to a large extent by the higher evaporation-

rate. The light factor plays a very minor role in the de- termination of plant types, although as might be expected, the intensity on the southern slopes with their chaparral formations ?nd much bare, light-colored soil is a great deal higher than that on the northern, forest covered side.

The prevailing wind of the ridge is from a northwesternly direction, this being almost universally true during the dry season. During the wet season the northwest winds are still the commonest, but the storms which bring the winter rains are generally from the southwest. Thus the northern slopes receive most of the dr-j summer winds and the southern ones those of the winter storms, "but there is no evidence to show that wind is an important ecological factor. 19

K. Vegetative Zones

As has "been previously mentioned, there are three distinct vegetational areas on the ridge, these being the forest, chaparral, and grassland formations. The forests in general occupy the northward facing slopes of the ridge and are also found along the banks of the streams. The chaparral is mainly found on the dry, southern slopes. Originally it occupied the major portion of the ridge, but in recent years much of it has been cleared away, although there are still several pure stands present. Of these, the two principal ones are in the southeastern ana

southwestern areas of the ridge. The grasslands occur throughout the more or less level valleys and gently sloping hillsides and occupy most of the space which has been cleared of chaparral. In these areas are found ex- panses of wild oats and other grasses, occasional scattered oaks and some shrubs, as well as many introduced weeds. The inroads that man has made upon the ridge have greatly affected the plant life of the area, particularly in the case of the chaparral. Much of the cleared area on the ridge itself is now devoted to the grazing of stock and parts of the valleys surrounding it are used,for agriculture! purposes. Searsvllle Lake is a popular recre- ational area and throughout parts of the ridge there are numerous picnic grounds and tables. IV INT FORMATIONS

A. Time of Flowering

The time of flowering of the various plants in each of the three vegetational zones was carefully observed throughout the entire survey, and notations were made as to the month in which each species was first found in bloom. In the case of a few plants, however, the blooming periods were entirely missed and fruiting or merely herbaceous specimens were collected later during the year.

In situations such as these, the plants were listed as beginning anthesis during the month in which they \vould normally have been found. This information was obtained from the taxonomic works of Abrams (1 & 2) and Jepson (8).

A total of 299 species of spermatophytes was collected on the ridge during the survey. Of these, the great majority was easily placed in one of the distinct ecological zones, but at the same time, quite a few plants were collected in the transition areas between two zones . This was especially true of the chaparral, where several plants were collected on its outskirts, bordering both it and the grassland, and of the more openly wooded, yet grass-covered hillslopes. In the latter case it was difficult to decide whether plants collected from those areas should be placed in the forest association or in the grassland. Accordingly,

20 MAP OF THE VEGETATIVE ZONES OP JASPER RIDGE

LEGEND

FOREST CHAPARRAL ®r =«-. ran Lj Ji££^t-H:£-J GRASSLAND

a number of plants are listed as occurring in two or even • " all three of the vegetational formations. Some examples of these transitional area plants are: Chlorogalum pome^riQi aninn , Geanothus thyrsi floras , and Sphe.cele calycina , which occur in both the forest and chaparral; Brodiaea

media, Achillea millefolium var. lanulosa and Anagallis arvensis, which are found in the forest and the grassland; Mavarretia heterodoxa, which grows both in the grassland and at the edge of the chaparral; diver si lob a and Schinocystis fabacea, which occur in all three of the vegetative zones throughout the ridge.

The mpnth_in which a plant is listed as first beginning an the sis is not necessarily the one in which the blooming season of that plant is st its peak. This is particularly true of several of the annual herbs, which were first observed blooming in late March, but whose maximum flowering period occurred in the early part of April. The following table (Table III) is a summary of the

number of species observed beginning or known to begin anthesis in each month on the whole ridge and in each of the three vegetational zones. Because the survey was not carried on during January and February, the totals for these months are grouped with those of March. This gives rather misleading results for the three month period. If these totals were to be broken down into monthly data, in all probability about 607o of the plants listed during this time should be included in the March totals, approximately 50/0 in February, and the remaining 10/b in January. 22

TABLE III Number of Spermatophytes Beginning Anthesis in Each Month on Jasper Ridge

Whole Ridge Forest Chaparral Grassland

January- March 86 38 12 April 96 38 9 May 63 19 3 June 27 11 3 July 12 7 2 August 11 2 1 September 2 1 1 October 1 0 0 November 1 0 0 December 0 0 0

Totals 299 116 31 183 23

The totals for the three vegetational areas exceed those for the ridge as a whole. This is because several

plants were listed as occurring in more than one vegetational zone.

By far the greatest number of plants begin their blooming season during the month of April, both on the ridge as a whole and in each of the three formations. The percentages of plants beginning anthesis in that month are: entire ridge, 32.1/«; forest, 32.7%'; chaparral, 29.03$; and grasslands, 34.4$. Other months in which there are large numbers of plants beginning to flower are March and May; 21.07% of all the plants on the ridge were first observed in anthesis during the latter month, and approximately 17.4$ in the former. Very few plants begin their blooming season in the late fall months; none was collected in December and only one each in October and November.

B. Forest

The forest areas of the ridge occur on the steeply sloping northern hillsides and along the banks of the streams. The most striking feature of the vegetation is its luxuriant growth, so altogether different from that of the chaparral. Although the trees are a rather small component of the formation, comprising approximately only 10/b of the total plant life of the area, nevertheless they are the dominant vegetational form. The herbs and shrubs of 24 this zone generally are not adapted for guarding against water loss, but instead have large, thin leaves which are lightly cutinized, and the shade cast by the trees assures the best development of these plants. There is a rather small percentage of evergreen plants, about 60$ of the trees and 65% of the shrubs being deciduous. Although the soil along the stream banks is generally of alluvial origin, throughout the rest of the formation it is of the sandy Altamont type, being in nature nearly identical with that of the chaparral area. The only difference between the two is apparently the large amount of humus in the soil of the forest. This humus, which is considerable to a depth of three feet, greatly increases the water-retaining capacity of the soil. This condition is reflected during the wet season, when the maximum growth of the forest plants occurs. During the critical period of the dry season, however, the water-content of the forest soil decreases until it is almost equal to that of the chaparral. The forest formation is one of the three general types of vegetation on the ridge. Like the chaparral and the grassland, it is made up of characteristic species which merge to a greater or lesser extent with the plants of bordering formations. Within the forest, as within the other two formations, there are smaller groups or associations, each of them influenced in some way by special physical or topographic features such as streams, lakes,

ravines, and steeply sloping hillsides. And within

these smaller groups are found transitional plants which merge with those of neighboring associations. There are several well-differentiated subdivisions in the forest, the principal ones being the densely shaded redwood community or association, the openly wooded community, of which Quercus Douglasii is the most characteristic tree, and the heavily wooded or Quercus ^agrvLfolia community. Perhaps the redwood area should be included as a part of the heavily wooded forest, for many of the same plants are found in both communities. Moreover, the only place on the entire ridge where the redwood occurs is a very small area in the northwestern part, along San Francisquito Creek. In spite of this, however, the vegetation of this small area is distinctive enough to warrant considering it as a separate community. The most prominent tree of the area is, of course, the redwood itself, Sequoia sempe rvirens. Scattered specimens of P_seudotsuga taxifolJjL, a typical redwood associate, are found on the steep slopes a little above the creek. There are many specimens of jAljius rhoicbifo^lia, Acer negundq var. californi^urn, Cornus californica and Umbellularia californica growing along the creek bank, as well as such shrubs as Rubu_s porvif 1 orus , jjubus vitifolius , , Holgcl.iscu_s discolor, .Co

ro strata var. jcajyjfpjrnica, Dire a oc c id entails f Whip plea modes_t_a, j?hus ciiyersiloba , and Euonymus qcclc entails . Some typical heros of the area are Smilacina amplejci-- paulis , Smilacina sessilifolia, Dispopum Hookeri , .?j^;Lsil_e var. giganteum, Lithophragma _a_ffini_s, > 2®}i9j?£rL8: Hij???^!^* Stachyg bull at a , and Tr ± out a 1 is eur op e ae^ . The heavily v^ooded or Quercus agrifolia community occurs throughout the steep northern slopes of the ridge, v:ith the exception of the area occupied by the redwood zone. It contains many of the same plants that occur in the redwood area, for there is a gradual merging of the two associations and it is hard to draw any definite line separating them. The most abundant trees of this type of forest are Quercus agrifolia, Q,uercus Kelloggii , Arbutus Menziesii and Aesculus Cfilifornica, as well as those trees in the redwood zone, with the exception of ^.S(U19i§ s emp e r v i r en s and Pseudotsuga taxifolia. The most abundant shr-ubs are those listed for the redwood community, and others such as Sympho ri c arpo s .slbus,

ancl AÂ®.?1. ô s a cs-lifornci are scattered throughout the area along the creek and on the hillsides. Solarium umb^llîferun occurs occasionally on the heavily wooded slopes. The herbs of the redwood area are also PLATE V

HEAVILY VyOODSD FOREST ON WORTH SLOP (GRASSLAND IN FOREGROUND) 27

common to the heavily wooded forest: other abundant ' ones are ^ic_romeria.- . chamissoni. s , Zypadena•> s Fremontii , Some of the herbs found mainly slong the banks 'of Ssn Prancisquito Creek or in the dry stream bed itself during the summer include Melilotus alb_a, £uncuis PA^.?.^? > Juncus t_enui_£ var.

vulgari s , Me 1 i_s_sa offl ci nali_s , Helenium puberulum^ and H^r_P_c_le_um lanatum. The operilv v;oodec forest v/hich occurs mainly on the top of the ridge and on the more gently sloping hillsides, is characterized by fouercus Douglasii . This is by far the ,::ost prominent tree^ although there are scattered specimens of Quercus lobata, Aesculus californica and Quer^cus ££r_ifpljâ. There are many grassland anc chaparral plants throughout the area; in fact this community nearly approaches the status of a transitional zone. Common shrubs found growing here include Photînija arbuti folia, Rhus diversiloba, Rhamnus jcalifornijca, Rhamnias crocea, Diplacus aur an t i a c u s , Ros_a Californica, Sphacele _c aly cîna , ^rj._qcîctyqn jc_alifornic_um, Ceanothus .sp^rejii ajtus , and Sympho r i c a r p_o_s Îbus. Many of the herbs of the grassland areas occur in this community. On some of the flat exposed places there are numerous specimens of Cast ill eij. var» Pouglasiij CalochortuLS lut eu s , and 28

Pljsctritds macrocera. Brodlaea Ixlolces Is frequent & " " ...... "" ~" |- locally in openly woooed spots. Other common species r i'* include Stel_larla media, Anjy?:aJLliji arvensis , Achillea * ml lief oil urn var. lanulosa. Stachys bulleta, P so rale a phy5o_de_is , Pedlcularis densiflora, Plectritis ciliosa, f * and Calochortus albus .

C. Chaparral

Chaparral is the name given to a formation common ;. to the arid west coast, v;hich consists largely of shrubs specially adapted to xerophytic conditions. Dr. Cooper (6) gives the following definition for this formation: "The chaparral may be defined as a scrub community, dominated by many species belonging to genera unrelated taxonomically , but of a single constant ecological type, the most important features of which are the root system, extensive in proportion to the size of the plant, 'the dense rigid branching, and preeminently the leaf, which is small, thick, heavily cutlnized and evergreen.11 Although much of the original chaparral has been cleared away, there are still a few areas on Jasper Ridge which are large enough to exhibit the character of the typical formation. These occur on the more gently sloping hills of the southeastern and southwestern parts of the ricige, and to a much lesser extent on a 29

few of the more gentle north-facing slopes. The latter

is the Arctostaphylos community, of which Arctostaphylos tomentosa is the dominant species. The chaparral of the southern slopes is of the Acenostoma community and. is "by far the most extensive type; here Adenostoma

fasciculatum domlnates. The soil on which both communities are found growing is meinly of the sandy Altamont group, derived from the sandstones and shales of the Franciscan and Chico formations. In mostplaces it is quite shallow and the roots of the chaparral plants penetrate some distance

into the rock "below. There is little or no humus present and consequently the water retaining capacity is very poor. At the end of the rainy season the water content of the soil is temporarily quite high ana during the spring months the greatest vegetational activity occurs, particularly during April, when soil-moisture is still abundant and air and soil temperatures are on the increase. Soon after the advent of the drj season, however, growth is necessarily stopped, due to the rapidly decreasing water supply of the soil. This depletion continues throughout the summer, until a critical period of severe deficiency is reached just before the arrival of the winter rains. The small, heavily cutinized leaves represent the modifications of the chaparral plants which help to PLATS VI

CEAPARRAL AREA NEAR SEARSV1LLE LAKE 50

counterbalance the high evaporation rate. An extreme example of this is evidenced in the leaf of Adenostoma ^ A?Ai9.\Ll^frum ; it is small, evergreen and needle-like. A relatively small number of species of plants

is found in the chaparral formation, particularly in the pure stands, where Adenostoma ^fasciculatum, Arcto-

S J^roj-Qj-Pj-LS > anc^ to a lesser extent, Quercus an(^- Ceanothus cuneatus constitute almost the entire vegetation. Trees are not normally found in the area. Other shrubs which occur rather infrequently are

Z^ot_inia agouti foil a , Geanothus sorediatus , Gercocarpus

be_tjalp_icie s , Prunus ilicifolia and Clematis lasiantha, which in some areas is found abundantly climbing over the shrubs . Around the edges of the patches of pure chaparral are found several transitional plants which do not occur in the middle of the formation. In all probability they were not originally members of the true chaparral

growth, but they now seem to definitely belong to it. Included in this group are such shrubs as ^iglajcu^ diversiloba, Sphacele calycina,

Baccharis pilularis , Lotus scoparius, Eriodictyon

££liC°_nii9H?l* Ceanothus thyrsiflorus and Artemisia Apparently the only herbs which -can be classified as belonging to the chaparral formation are,

like the above plants, ones which are found only around 31

the edges of the pure stands. Some of the most common ones are Navarretla heterodoxa, Epllobium paniculatum, californica, Smilacina amp1exi c aulis, and

£aJDace_a«

D. Grasslands

The grass formation is found for the most part on the flat tops and the gently rolling slopes of the ridge and in the valleys surrounding it. These areas are characterized by many species of grasses and low herbaceous plants which germinate with the early winter rains, bloom and. fruit during a few weeks in the spring, and then wilt and die with the arrival of the dry season. The pure grassy areas grade into both the chaparral and the open forest. The low rolling hills of the area are covered with the plants of the grass formation and are also dotted with scattered specimens of Quercus E»ougla_sli, Quercus lobat_a, and G;ue_rcus j^rifolija. This tree and grass association is a characteristic and typical one, although the oaks themselves are not considered as true members of the grassland formation.

The most abundant plants on the rolling slopes are a large number of grasses, of which Avena fatua and Avena barbata are the most common. Briza minor, Bromus hordeaceus. an^ Bromus racemosus are found abundantly also. Some of the conspicuous early blooming herbs are Baerla chrysostoina, PLATE VII

GRASSLAND, WITH SCAl'TER^i) SPECIMENS OF QUERCUS AGRIPOLIA Ai^D qUaRGUS LQBATA humi stratus , jLotus subplnnatus, Ranunculus cali-

fornicus , Eschscholt z i a c al i f o rni c a , Plagiobothrys

.M 9 Lupinus nanus , Li nan thus parvif lorus , and. Oenothera ovata and Flatygtemon californlcus are two low-growing plants which are frequent in the pastures at the bottom of the ridge. Erodium botrys

an(^- podium cicutarium are extremely abundant in the early spring, and Brodium mos_chatum is almost as common. Later in the spring several species of clovers, especially Tj^f^ljLum tr^^njb atjum , .Tj'.ifol^ium c i liatum , ^r_ifojL_ium gracilentum, and Tr i folium bifidum var. decipiens , begin to flower abundantly. ^£odl.ae_a I_&JX.B. and Br od 1 aea capitata are common at this time, as are CrOjaejfcjija quadri-

vulnera, ^^vSLlY"11!-^ subacaulis , Plantago erect a, and Lomatiuin d^j^c^rpjjin . Still later, at the beginning of the summer, the succession of flowering passes on to such plants

as Godetia amoena, Galochortus luteust Galochortus venustus , Delphinium hesperium, Lotus americanus , Lagophylla ramo- sissima, and Pemizonia conp:esta var. luzulae folia. The transition area between the grasslands and the openly wooded forest is indistinct, for, as has been previously mentioned, there are numerous grassland species which ere commonly found growing in open spots within the "confines of the forest itself. There are, however, some herbaceous plants which seem to grow most frequently along the border between the two communities. These plants seem to need partial shade, but not as much as in the denser woods. They do not compete with the shrubby undercover, but are usu ally found in small open patches underneath the trees. A few of the more common species are Monti a perfoliata,

^jy-liS6.* Lithophragma af finis, and ^itjbri^scus

Other communities within the grasslands are those of the meadow in the strip of serpentine, of disturbed

areas near buildings and along roads, and of the flat

area surrounding the lake. The former is by far the most important of the three, for this strip is apparently the only area on the ridge where the vegetation is affected by the geological formation underlying it. The soil, which is composed almost entirely of decomposed serpentine, is very shallow and there are man:/ outcrops of rock through out the area. There is a negligible amount of humus and the water retaining capacity is extremely poor, as is the organic-matter content. Some plants found growing in the area also occur elsewhere on the ridge, but there are some which are limited to this habitat alone. Among these are

Lay! a platyglossa, Crypt antha flaccida, Arenaria Douglas il . Allium s err a turn, Hordeum nodosum, Sitanion .iubatum , and

_0rthocarpus f aucibarbatus . Other herbs which occur here quite frequently, but are found in other sections' of the

ridge also are Galochortus XeJluAkJi,?. > Stipa £ulchra, B > Brodiaea 1 axa , Brodiaea coronaria , Godetia quadr i_vuj.ne_ra , Godetia amoena, Plant 9 go jsrjecta, Linanthus 34

L?JL°£ii§> an(i Bgeria chrys'osterna, and such shrubs as Diplacus aurantiacus-j Photinia arbutifolia, and Quercus durata.

The association of disturbed areas near roads, buildings and cultivated fields is characterized by the presence

of many introduced and native weeds, which form the dominant vegetation. Among the most common of these are Picris

echloldes. Brassica campestris, Brasaica aryensls, Rapha- nus sativus, Sonchus oleraceus, Sonchus asper, Cirsium Occident ale , Cent a/urea melitensis, and Centaurea solstit-

i§3UL§- j^'ipsacus fullonum often covers large areas along roadways, forming almost pure stands. Avena fatua and

Avena .parbjata are the most common of the grasses found in

such areas. Many of these common weeds are also components of the community which i.s found immediately surrounding the edge of the lake. Other plants which commonly occur on the moist soil of that area are Polygonum Muhlenbergii, Typha i§:.tiH9ii§:> ^^"^Q.x crispus , Rumex obtusif olius, Polypogon monsDe1iensi^, Mentha pulegium, Boisduvalia densiflora, PI ant ago lanceolata. V ECOLOGICAL INTERPRETATIONS

An explanation of the presence of the typical vegetation of the grasslands probably lies in a consideration of the soil factors. Drainage is good to excessive throughout the grassland area and the soil is generally fairly shallow. There is little humus and only a moderate amount of subsoil present and the evaporation rate is undoubtedly very high, especially since there are very few woody shrubs or trees throughout the area to provide any shade. Ac- cordingly, it may be assumed that the water-retaining capacity of the grassland soils is extremely poor. This is borne out by the fact that the typical annual herbs of the formation complete their entire life cycle within a period of five or six months. Germination of the seeds occurs with the coming of the first winter rains and growth procedes rather slowly during the early months of the year. Then in the spring, while soil moisture is still high, there is great vegetational activity, and within a period of a few weeks flowers and fruits are produced. This phase is followed by the death of most of the herbs and throughout the dry summer there are extremely few plants found growing on the brown hillsides. For a comparison of the vegetational forms in the forest and chaparral formations it is well to consider the

35 56

results obtained by Dr. Cooper (6) in his study of the broad-sclerophyll plants. He concluded that many factors are indirectly involved in an explanation of the greater size and luxuriance of the forest vegetation growing upon the north-facing slopes, and the absence of the more meso- phytic species from the south-facing exposures, but that fundamentally the problem is one of ?/ster-balance. During the height of the rainy season there is a plentiful supply of soil-moisture and a minimum of evaporation in both habitats, but the atmospheric and soil temperatures are lo?/, and there is consequently little growth. Then as the temperature rises, the growth rate also increases. However, at the same time the rains are decreasing in frequency and amount and the evaporation-rate is rising. Thus it is seen that the amount of actual growth is de- pendent upon the ratio of water-supply to water-loss, and this balance is more favorable in the forest of the north-facing slopes. It follows that the greater size and luxuriance of the plants on these slopes is due to the fact that the soil-moisture is more abundant and evaporation less rapid during the grov/ing period, whereas in the shrubby chaparral associations, the reverse holds true. Dr. Cooper summarized as follows: "Our conclusion, then, extended to the larger vegetation units, is that the fundamental distinguishing difference between the two bro,-d-sclerophyll climaxes — their continuing cause so to sDeak--is in the water balance and its variation, whatever 37 the indirect factors influencing it; that its importance is equally divided between wet and dry seasons, the greater excess of supply over loss in the forest during the growing season explaining the size and luxuriance of the plants living there, and the higher evaporation rate in the chaparral during the dry season, with equally severe soil-moisture conditions, accounting for the absence of rnesophytic species in that habitat." (6,p.71] VI ANNOTATED LIST OF SP-Hl KM AT OP BYTES POUND ON JAoPEK RIDGE

Following is a list of the 299 species of spermatophytes, representing sixty families, which were collected on Jasper Ridge during the survey. For each plant, notations are made as to the area in which it »;as collected or occurred most abundantly, the time in which it was observed or was known to be in flower, and its comparative abundance (rare, frequent, common, abundant).

Jepson* s Manual of_ the Flowering Plants of California (8) was used in the classification of the majority of the plants, and they are listed here in the order in which they appear in this book. In nearly every case the names of the plants are those that Jepson used; however in a few instances plants were collected which are not included in the Manual. Examples of these are Vicia v^iJLlojsa and

Carduus ^enulTlorus.

SPSRMATOPHYTA

GYMNOSPERMAE

a (Lamb.) Britt. Douglas fir; Douglas Spruce . Occurs rather infrequently on steep north hillsides. The staminate cones appear in March . 58 39

Sequoi_a J^npe_rvlj^ens (Lamb.) Encll. Redwood. Frequent along San Prancisquito Creek, the staminate cones appearing in February.

ANGIOSFERMAE

MONOCOTYLEDONS

. ^ L. Common Cat-tail. Common along, the shores of Searsville Lake. Col- lected in August.

Alismaceae

Alijsma pi ant ago L. Y^ater Plantain. Relatively infrequent along the lake shore. June and July.

Gramineae Broimus rigidus Roth. 'Ripgut1 Grass. Abundant In open fields and hillsides. April and May. Bromus hordeaceus L. Soft Cheat. Very abundant throughout the ridge on open hillslopes and in fields. April and May. Brojnus j^^jsinosus L. Very abundant in April and May in fields and on open slopes. 40

Schrad . Frequent in open fields in April and May. Brpmus c^rjjnatxis H. & A. California Brome Grass. Common on openly wooded slopes and in fields. Blooms in April and May. Bromus grandis (Shear) Hitchc. Infrequent on openly wooded hillsides. May.

o.ctoflora Walt . Relatively infrequent. Pound on openly wooded hillside in May. ^§dkuCja myuros L. Rat's-tail Fescue. Frequent along roadsides and in open fields, in April and May.

Z!L?Lkyj?_a- Elmer 1 Scribn. £ Merr. Found infrequently on wooded hillsides in May.

Briza minor L. Very abundant throughout the ridge in open fields and on openly wooded slopes. March through May. Blymus glauqus Buckl. Western Rye Grass. Frequently found in open fields and hillsides in

April and May. .Sitanion jubatjura J. G. Sm. Frequent in the serpentine area of the meadov;. May and June . Sltanion Hystrix (Nutt.) J. G. Sm. Infrequent. Found on openly wooded slope in July. 41

Hordeum murinujn L. Wall Barley; Farmer's Foxtail. Common in disturbed areas, especially along roadsides. March to May. Hordeum nodo sum L. Meadow Barley.

Limited to the serpentine of the meadow, but frequent there . May and June .

I^JLiffl BliLk^J-j?JCH*S Lam. Italian or Australian Rye Grass Common in open fields, on openly wooded slopes, and.

along roadsides. April and May. cristata (L.) Pers . Frequent in open fields and on openly wooded slopes. May .

A.!LeHa ?§^ua -k. Wild Oat. Extremely abundant throughout the entire ridge, particularly on open hillsides. March through May.

Ayeria barb at a Brot . Very abundant on open hillsides throughout the ridge from March to May. Generally found growing with Avena

f atua . jg. cjirjophyllea (L.) Nash. Common on openly wooded slopes. Found blooming in

A£rostis vg^r t i ci 11 at a Vill. Infrequent. Found on wooded hillside in April.

A££9.stA§ l°Jj:ffj-.13-gula Hitchc. Rare. Found growing in moist area near the lake in

July. 42

n lutosus (Poir.) Hltchc. Infrequent near the lake shore in June.

9jS?J5 inonspeliensij (L.) Desf. Beard Grass. Common near the edges of the lake in June and July.

Stipa £ulchra Hitchc. Frequent in the serpentine of the meadow in April and May.

Gyperaceae Gyperus XLrejis Michx. Infrequently found along San Prancisquito Creek in June and July.

C^arex b^J^jirsie ^©w. Rare. One plant found on creek bank in July.

Juncaceae

Juncus patens Mey. Common Rush. Frequent along San Francisquito Creek and on wooded slopes. April and Iv-ay. Juncus t^ejiuijJ var. cjonge_sj;us Engelm. Rare along San Francisquito Creek in June.

Juncus oxyrneris Engelm. Infrequent, found growing along the creek bank in

July.

Liliaceae

Zyj^adenus Fremontii Wats. Star Zygadene. Common on wooded hillsides, blooming from March to

May. (Ker.) Kunth. Soap Plant. Common in open woods, especially along the roadside,

and at the edge of the chaparral. Blooms in May and June Allium serratum Wats. Limited to the serpentine of the meadow, v/here it is locally frequent in May and June.

B£2

B r od i a, e a i xi o i d e s (Ait. f.) Wats. Golden Brodiaea. Frequent locally in patches on openly wooded hillsides . May . hyacinthina ( Lindl . ) Baker . White Brodiaea .

Relatively infrequent on openly wooded slopes and in the meadow of the serpentine. May. Brodiaea coronarip (Salisb.) Jepson. Harvest Brodiaea. Common on hillsides and open fields, flowering in

May and early June. Brodiajea cajDitata Benth. Blue Dicks. Frequent on open slopes and fields from March until

May . Brodiaea pulchella (Salisb.) Greene. Ookow. Common on open hillsides in April and May.

Calpchortus luteu.8! ^ougl • iellow Mariposa. Frequent on grassy hillsides and openly wooded slopes in late May and June . 44

White Iv'ariposa. Frequent in open fields and hillsides and in the

meadow of the serpentine. May and early June. Calochc^rtus SLltrus Dougl . White Globe Lily. Locally frequent in openly wooded regions. Pound blooming in May.

Liliutn £jar^ljLnuin Kell. Tiger Lily. Rare. One plant found in the deep shade of the redwood area in June . Disporum Hooker i (Torr.) Britt. Fairy Bells. Infrequent in the redwood area, blooming in March Smilacina gessi 1 i folia Nu 1 1 . Slim Solomon. Frequent in the deep shade of the forest on the

north side of the ridge. Blooms in March and April. Nutt. Fat Solomon. Common, found on densely v7Ooded slopes and near the edges of the chaparral. March to May. ^i Ilium J.e.s_sile L. var. ^gs^teinn H. & A. Common Trillium Frequent on the heavily wooded north slopes. March

and April .

Iridaceae V Sisyrinchium bellum Wats. Blue-eyed Grass; Nigger-babies. Common on open hillslopes and in fields. March and

April. 45

Orchidaceae Kabenarla Michael! Greene. Rare. Pound in shady woods. June.

DICOTYLEDONS

Salicaceae a Bebb. Red Willow. Abundant in thicket near edge of lake. The catkins appear in March. J3ali_x ^ind.s_i_ana Bentham. Vralley Willow. Comparatively infrequent. Pound at edge of road above lake. March. Salix lasiolepis benth. Arroyo V/illov/. Abundant in thicket at edge of lake and along the streams. March.

Betulaceae Alnus rhomb!foila Nutt. White Alder. Common along the banks of San Prancisquito Creek. It flowers in January and February.

Gorylaceae

CojTXlJi8- .1*0strata Ait. var. californica A. DC. California Hazel. Very abundant along San Prancisquito Creek. The catkins open in February and March.

auercus lobata Nee'. Valley Oak. 46

Frequent in the lower parts of the ridge. It flowers in April . j^ercus Douglasii H. & A. Blue Oak.

Abundant throughout the openly wooded, forest. April .

Quercus durata Jepson. Leather Oak. Frequent in the chaparral and to a lesser extent in the serpentine area in the meadow. April. Quercus agrl_ folia Nee. Coast Live Oak.

Found abundantly in the heavily wooded forest and less commonly on the openly wooded slopes. Flowers in March and April. Quercus Wislizenii A. DC. .Interior Live Oak. Frequent shrub of the chaparral. Also found occasionally in the heavily wooded forest. April. Quercus Kelloggii Newb. California Black Oak. Frequently found on the higher openly wooded, slopes as well as on the shady north slopes. Blooms in February and March.

Juglandaceae

Juglans Hindsii Jepson. California Black Walnut.

Rare. One very young plant was found in the shady woods near San Francisquito Creek in November.

Urtica gracilis Ait. var. holosericea Jepson.

Frequent along the banks of the creek in July. 47

Loranthaceae

Phoradendron villosum Nutt. Common Mistletoe. Frequent parasite of the oaks throughout the ridge, occurring mainly on Uuercus lobata and to a lesser extent on Quercus Douglas!!. August and September.

Polygonaceae Polygonum Muhlenbergii V/at s . Common plant of the shallow area of the lake. It was collected at the edge of the lake in August. Polygonum aviculare L. Wire Grass; Yard Grass. Infrequent. Pound on edge of road above the lake, blooming in November. jly^x crispus L. Curly Dock. Commonly found around lake and along the roadsides. It blooms in May and June . Rumex ^pji^lomejratus Murr. Green Dock. Frequent in disturbed areas along roadsides and near the lake. May and June. Rumex optusifoJULus L. Bitter Dock.

Frequent around the edges of the lake and along roadsides. May and June. _Rumex acetosella L . Sheep Sorrel .

Common along roadsides and in fields. April and May m Dougl.

Abundant on open hillsides in August and September. 48

Portulacaceae Calandrina caulescens var. Menziesii Gray. Red Maids.

Abundant on open slopes and in grassy fields in March and April.

Montis perfoliata. (Donn) Howell. Miner's Lettuce.

Abundant on moist slopes from March until May. Often found growing at the base of oak trees.

Caryophyllaceae Cerastium vi s c o sum L. Mouse-ear Chick\veed. Common in open fields and along roadsides during March and April. Stellaria medj^a (L.) Cyr. Common Chickv/eed. Very abundant throughout the ridge, occurring in open fields and on both openly and densely wooded: slopes. It was found blooming to some extent almost throughout the whole period of the survey, but the main flowering period, is from March until May.

Frequent in the strip of serpentine. April and May.

Silene sOli0 L» Windmill Pink. Abundant in fields and along roadsides from April to May.

Ranuncul ace ae

Actaea. spicata L. var. arguta Torr. Relatively infrequent shrub of the heavily wooded north slopes. It blooms in March and April. 2®lP.^A?iiySl Z££i®£§L£ffl T. & G. Royal Larkspur. Frequent on openly wooded hillsides in 'May. DelpMnium hesperium Gray. Western Larkspur. Common on dry, openly wooded hillsides in May. Thalia trum polycarpum Wats. Frequent on the more heavily wooded slopes , -and blooming in March and April. californicus 3enth. California Buttercu. Common on grassy slopes and. in fields from February to April. C^lema_t_i_s j^s^antha Nutt . Pipe Stem. Common vine of the chaparral, often climbing abundantly over the shrubs, and blooming in March and April.

Lauraceae Umb e 1 1 ul aria c al i f o rni c a Mutt. California Laurel; Bay Tree . Common along stream banks and on the north slopes. February and March .

F ap a v e r a c e ae Platys^temon californicus Benth. Cream Cup. Relatively infrequent in moist meadows and along roadsides in February and March. 3S schscho Itz i a californica Cham. California Poppy. Common in open fields and meadov/s from P§bruary until V;ay. 50

Cruci ferae

.officinal_. _. e (L.) Scop. Bedge Mustard Frequent in open fields, mainly along roadsides April and May.

avus L. Wild Radish. Common in disturbed areas, mainly along roads and around the lake. It blooms to some extent throughout the year, but mainly from February to May. Bras sic a £aj^ej3jtrjLs L. Common Yellow Mustard. Abundant weed of open fields and disturbed areas.

It was found blooming by the lake in November, but the main flowering period is from February to May.

Bj^jssi.cj* aryensis (L.) B. S. P. Charlock. Similar to the above species, and often found growing with it. Distribution, abundance, and tine of flowering are about the same .

^g.rj^8-r.e-a: vulgaris (L.) R. Br. ViTinter Cress. Frequent along San Prancisquito Creek in April and

May . Radlcula na ai t_u r ;t i urn- aqua t i cum (L.) Britt. & Rendle.

Water Cress. Rather infrequent along the creek. May and June. LejDidium nijtldum Nutt. Common Pepper— grass . Frequent on open hillsides and in the strip of ser oentine in March and April. 51

> ur 3 > P.gJPJLglAg: ^ -' - .Q:" _Pfist.pris (L.) Moench. Shepherd's Purse. Common in open fields and along roadways. February to May.

Grassulaceae

JL?AlS3 J^Attk^QJJTjPJLi1™ Hook. Infrequent on shaded moss-covered rocks in the heavily wooded forest. Collected in July.

Saxi f r agac eae Woodland Star. Frequent in both heavily and openly wooded areas. April and May. Tel 1 ima grand if lor a (Pursh) Dougl . Fringe Cups. Infrequent in the deep shade of the redwood zone. Found blooming in April and May. Heuchera m^rantha Dougl. Frequent along the banks of San Francisquito Creek. May and June . Whlpplea INpJ^stjs Torr. Common in the heavily wooded area along San Pran- cisquito Creek. March until June. fti£Les- ^SSli^IlSJSffi var. glutinosum Loud. Flowering Currant. Common, especially in the thicket at the edge of the lake. Pound blooming in March . Ribes call fp rn i cum H. & A. Hillside Gooseberry. Common along. San Francisquito Creek, and also in the more openly wooded forest. It blooms from January to March . Ribes Menz^ie_sil_ Pursh. Canyon Gooseberry. Cornperatively infrequent in heavily wooded areas and along the creek bank. March and April.

Rosaceae Z^7A0^§^!£1i?. .^^PA^^Jis (Pursh) Kuntze. Ninebark. Common along Sen Rrancisquito Creek, flowering there in April and May. Iip_lod_i^s_cu.s dJLSColor (Pursh) Maxim. Cream Bush. Common along the stream banks and on hee.vily wooded slopes. It blooms in late May and June. Rubus jDaryjLfl,oru s I\Tu 1 1 . Thimb 1 e -b e r ry . Common along the creek, mainly in the redwood area. April and May. Rubus vi_ti_fqlius C. & S. California Blackberr;y. Frequent in heavily wooded areas and along the creek, flowering from April to the last of May. C. & S. Wood Stra?/berry . Found mainly in the deep shade of the redwood area, where it is relatively infrequent. It blooms in February and March and the berries ripen in May. Potent ilia g;landulosa Lindl. Common in wooded areas and along the creek bank. It flowers from March until Ivlay. 55

Ro.s.a jcalljrornlca C. & S. California Wild Rose. Quite abundant throughout wooded areas of the ridge, often near creek banks. It was observed flowering from April until August.

Nutt. Wood Rose. Confined to shady areas near the creek, blooming in April and May.

betuloides Nutt. Hard Tack. A frequent shrub of the chaparral, blooming from March until May.

Adenostoma ^as^jcuj-jatum H. & A, Chamise. Extremely abundant in the chaparral, being the dominant plant of the formation. It blooms in late May and June . Prunus ilici folia Walp. I slay. Frequent along ravines and at the edges of the

chaparral, flowering in May. rbutifoliR Lindl . Christmas Berry; Toyon. Abundant in openly wooded areas and in the chaparral. It blooms in June and July and the berries turn red in November and December.

Leguminosae

Lupinus derisj^f^qrus^ Benth. Infrequent on grassy hillsides in April end Ivsay. nanus Dougl. Very abundant throughout the ridge on grassy slopes 54

March and April.

Lupinus Mcolor Lindl.

Rather infrequent on open slopes and in fields. March and April. JiUjpJjnrus JFojrmpjms Greene. Infrequent or rare in open fields. May. Lupinus albifrons Benth.'

Frequent on hillsides and grassy slopes. April and Ms;/.

Ile^.^c_a.£°, hispida Gaertn. 3ur Clover. Abundant in fields and pastures and along roadsides. Blooms from March until June.

Melilotus alba L>esr. White kelilot. Frequent along creek banks from July to October. Melilotus indica All. Yellow ;V,elilot. Infrequent in open fields. May and June. Trifolium tridentatum Lindl. Tomcat Clover, Very abundant throughout the ridge in fields and on ODen slopes. March to May. Trifolium involucratum Ort. Cow Clover. Infrequent along stream banks. April to June.

TrifolAum 5a^!5.l£§Z"™l Torr. Common in grassy fields and on openly wooded slopes.

April until June. Tri folium m:lcrocej)halum Pur sh.

Common on open hillsides and in fields. March to i/ay bifidum var. de_cipiens Greene. Pinole Clover.

Abundant in moist grassy fields. March to May.

.lliatum Nutt . Tree Clover. Common on open grassy hillsides in April and Hay. gracilenturn T. & G. Pin-point Clover. Frequent on open hillsides and in fields in April and May.

Trifolium adbopurpureum T. & G. Rancher! a Clover. Frequent in moist, grassy fields in March and April. hum! stratus Greene. Hill Lotus. Abundant on grassy hillsides from March to June. Lotus subpinnatus Lag . Very similar to the above species, and usually growing with it. Distribution and abundance are the same I.otus amer_ic_8.nus (Nutt.) Bisch. Spanish Clover. Very abundant in open fields, blooming from May to

October.

JkoJlus ^PJiaJ:liH§ (Nutt.) Ottley. Deerweed. Abundant in openly wooded areas and on the edges of

the chaparral. Blooms from May until November. Psqralea physodes Dougl. California Tea. Common in open spots on wooded slopes, from April until June. Vicia j^ativsi L. Goranon Vetch. Common in fields and along the roadsides. March to

May. 56

L. Smaller Common Vetch. Frequent in fields and along roadsides. April to June .

Vlcia villosa Roth. Winter Vetch; Wooly Vetch. Hether infrequent, mostly along roadsides. April until June.

Lathy rus vestitus Nutt . Frequent on shady hillsides, especially the more openly wooded ones. March and April.

Geraniaceae Geranium dissectum L. Common Geranium, Common in moist fields and open slopes from Febru- ary to May. Brodium botrys Bertol. Extremely abundant, particularly in pasture lands.

It blooms to some extent throughout the year, although the main flowering season is from February to May. Erodium moschatum L'Her. White- stem Filaree. Abundant in fields and pasture lands, blooming mainly from February to May. cicutarium L'PIer. Red-stem Filaree. Very similar to the above two species in distribution, habit, and abundance.

Anacardiaceae

Rhus diver siloba T. & G. Poison Oak. This is probabi:/ the most abundant plant found on 57 the ridge, occurring to some extent in all three of the vegetational formations, and often forming dense thickets

It was observed in the field but was not collected. It flowers in April and May.

Celastraceae Eupnymus occidentals Nutt. Western Burning Brush. Frequent in the shady woods along the streams. June

Aceraceae Acer macrophyllum Pursh. Big-leaf Maple. Hather infrequent along the banks of the streams. Flowers in April. Acer negundo L. var. californicum Sarg. Box Elder. Common along the banks of the streams. April.

Sapindaceae Aesculus californica (Spach) Nutt. Buckeye.

Abundant along the stream banks and on the wooded north slopes. May and June.

Rhamnaceae

Rharnnus ^alijfornica Esch. Coffee Berry. Common in densely v;ooded areas and to a lesser extent on openly wooded slopes. June. Rhamnus crocea. Nutt. Red-berry. Frequent shrub of openly wooded areas. It flowers from February to May. 58

Ceanothus thy r s 1 f 1 o ru s Esch. Blue Blossom. Common shrub of_.openly wooded slopes, occasionally found in the chaparral. March and April. sorediatus H. & A. Jim Brush. Frequent on wooded slopes and more rarely in the chaparral. February and March. Ceanothus cuneatus (Hook.) Nutt. Buck Brush. Common member of the chaparral, less frequently found in openly wooded areas. It flowers from January through March.

Malvaceae Malva -Qarvi flora L . Che e s e we ed . Infrequent along the roadsides and in other waste places, blooming from March until August. ^^iPJL?: H^^®£k°£§ G^ay. Checker Bloom. Found infrequently in fields and along the roadsides, in March, and April. (Nutt.) Arthur. Rare, growing on a hillside along the road. May.

Violaceae Viola ocellat^a T. & G. Western Heart's Ease. Infrequent. Pound growing only in the deep shade of the redwood area, and blooming in March and April.

Datiscaceae Datis_c_a glomerata (Presl.) Baill. Durango Root. 59

Infrequently found, growing along the banks of San Prancisquito Creek in May and June.

Gucurb i t a c e ae fabaceji Naud. Common Man-root. Found growing almost throughout the ridge, although not really abundant in any one spot. It was observed flowering in March and April.

JDIrca occic.entalis Gray. Western Leatherwood. Frequent shrub of the shady north slopes, often growing close to the creek. It flowers in February ana March .

Qnagraceae Epilobium Watsonii var. f r an c i s c anum Jepson. Infrequent in the moist area around the lake in August . Epilobium calif orni cum Hausskn. Rare. One plant found near the lake in July.

Frequent along roadsides, particularly in the chaparral area, in July and August. ^j^s^uyalia d,ens_ij^ora ( Lindl . ) Wats . Infrequent in the moist ground around the lake in August. 60

. ... Doupl. infrequent on _openly wooded slopes in May. lia .§Si9.§n§: (Lehm.) Lilja. Summer's Darling. Abundant on open dry slopes and in the serpentine meadow in June.

Godetia qu ad r i vul ne r a (Dougl.) Spach. Abundant on open and wooded hillsides in May and June .

Oenothera j^vajba ftutt. Golden Eggs. Frequent in moist fields and meadows in 'T'ebruary and March .

Umbe lli ferae jL^APik?: Menziesii H. & A, Gamble '^Veed. Frequent in the shady woods of the north slopes

from March until May. Sanicula bipinnatifida Dougl. Purple Sanicle. Gpinmon on open grassy slopes in March and April. vularl (L.) Pers. Bur Chervil. Common on wooded hillsides in April and May.

Osmorrhiza nuca Torr. Common in the shady v/oods near San Prancisquito Creek. April and May. Torilijs nodp^sa (L.) Gaertn. Knotted Hedge Parsley. Frequent on openly wooded hillsides. April and May. Conium m^culatum L. Poison Hemlock. 61

Common on the shady, moist ground of the heavily wooded forest. April to June. _Carum .^airdneri Gray. Squaw Root.

Infrequent on both open and openly wooded hillsides in June.

^B^^k®. .^a?51®j?i£9J£ P r e s 1. Rare along San Francisquito Creek in July. Heracleum Aajoatum Mich:x. Cow Parsnip. Locally frequent along the creek banks in May and June.

i-^^iiS utj£i cuJ-,&tum (T . & G.) C . & R. Common on open grassy hills from March until May. Lomatium nis^qc^argum (Nutt.) C. & R. Infrequent on open hillsides in April and May.

iPJ^liyKriasycarpu m(T . & G.) C. & R. Abundant on open grassy hillsides and in the serpentine meadow from March until May.

Garryaceae G8Lrry;a elliptic a Dougl. Silk Tassel Bush. Infrequent, collected in May in openly wooded area

near the chaparral.

Cornaceae Cornus ^alifoiinica C. A. Mey. Creek Dogwood. Frequent along the banks of San Francisquito Creek, blooming in May. 62

Be nth. Infrequent along the creek banks. May and June.

Ericaceae .js Mejizlejii Pursh. Madrono. Frequent in heavily wooded areas, mainly on the north slopes. March.

^^°Atj*£hylos_ tomentosa (Pursh.) Lindl. Common shrub of the chaparral, particularly on the gentle northward slopes. Flowers from January until March .

Primulaceae

Dodecatheon J^nder_sonj.i Gray. Mosquito Bills; Sailor Cap; Common on openly wooded as well as grassy slopes. Blooms from February to April .

Tri entails eurojDajsa L. var. 1 at i folia Torr. Star Flower. Frequent in the deep shade of the redwood zone and limited to this area. It flowers in March and April. Anaj^aJJULs arvensis L. Poor Man's Weather-glass. Abundant throughout the ridge, and especially common

in fields. It blooms to some extent during the entire year, though the main period is from March until May.

Apocynaceae

Rare. One plant was found in August on the bank of San Francisquito Creek. 63

G onvo 1 vul ac e ae subacaulis Greene. Frequent in meadows and pasture lends. April and May . Convolvulus luteolus Gray. Rare. Occasional plants were found growing over the shrubs at the edge of the chaparral in May. Pj?IlYJlly^Al*s ar yen sis L. Bindweed; Orchard Morning-glory. Frequent, especially in the pasture and cultivated lands. May to October.

Pol emoni ace ae ^^i<53i.?1 heterophylla Hook. Frequent in shady areas of the v;ooded slopes in March and April. Navarre t i a he t e rodoxa (Gray) Greene. Common on dry hillsides and at the edge of the chaparral in June and July. Linanthus ajnbiguus (Rattan) Greene. Frequent on open hillsides in April and May. Idnanthu s parv i f '1 pjf'u j> (Benth.) Greene. Very abundant on open hillsides and in the serpentine meadow from March until May.

Hy dr ophy 1 lace ae Nemophila aurijba Lindl . Fiesta Flov/er; Climbing Nemophila Frequent in moist shady spots of the northern slopes in March and April . 64

F. & M. Small V/hite Nemophila. Common in shady areas of the heavy forest and. along the creek "bank. March and April.

CQJ-l_£ognia Cham. Rock Phacelia. Frequent on rocky hillsides in May.

§£2wJlEi Gray. Relatively infrequent on dry slopes in May and June .

^^op-ict^rqn calif ornicum (H. & A.) Greene. Yerba Santa; Mountain Balm. Abundant in openly wooded areas and to a lesser extent in the edges of the chaparral. It flov/ers in May and June .

Boraginaceae gynog 1 o s s urn grande Dougl. Western Round's Tongue. Frequent in the shade along the creek bank and also on the less densely wooded forest slopes. It flowers from February to April. Amsi^ickia Dougl a si ana DC. Buckthorn Weed. Frequent in open fields and hillslopes from April to Kay. Amsinckla intejrmejdia F. & M. . Rare, found growing on a rocky hillside in May.

Crvptantha micromeres (Gray) Greene...... tZ.<£-~— — • —— - — — • ———.—-——-—— Infrequent, found on dry, rocky hillside in J-.-ay. 65

flaccid a (Dougl.) Greene. Frequent in rocky area of serpentine in April and May.

ha Torreyana (Gray) Greene Infrequent. Pound on cry hillside in May (Cham.) Greene. Frequent in open fields in April and May. KLagiobothrys nothofulvus Gray.

Common on open grassy hillsides in March and April.

Verbenaceae Verbena prostrata R. Br. Common Vervain. Frequent on dry open hills from July to September.

Labiatae

Scute: 1.lar;1.a tuberosa Benth. Blue Skull Cap. Frequent on openly v/ooded slopes from March to ?-'

Brunei l_a vulgar is L.

Frequent along, the banks of San Francisquito Creek in July and August. Melissa officinalis L. Garden Balm. Rather infrequent along the creek banks in July and

August. Micromeria Chamissonis (Benth.) Greene. Yerba Buena. Common in shady woods, especially near the streams.

It blooms in May and June. 66

calycina Benth. Pitcher Sage. A very common shrub of the openly wooded forest, and also occurring along the edges of the chaparral. It blooms from April until June. californica Benth. Limited to the areas of deep shade near the creek, and infrequent there. May to July. Stachys bull at a Benth. The most abundant of the mints on the ridge, and widely distributed. It occurs in both the openly and heavily wooded areas, and blooms from March to ^ay. Monardella volJLos^a Benth. Coyote Hint. Frequent on dry rocky hills throughout the ridge from May until August. ii®i?.tk5: pulegium L. Pennyroyal. Frequent in the area around the lake and in the creek bed from July to September. Ivlentha spi c at a L . Sp e arrnint . Rare. One clump of plants found on the bank of San Francisquito Creek in August.

Solanaceae L- Black Nightshade. Rare. One plant found flowering in August in the dry bed of San Francisquito Creek. Solarium umbelliferum Esch. Blue Witch. Frequent on the densely wooded north slopes, and 67

less commonly in the openly wooded, area. The main period of flowering is from March to June.

Scrophularia callfomica Cham. Common on moist \vooded slopes and near the creeks from March until ivay. Diplacus aurantiacus Jepson. Bush Monkey-flower. Abundant in the openly wooded forest and around the edges of the chaparral, "blooming from April until August. Mimulus H^tjbatus DC. Common Monkey-flower. Frequent in moist open places, especially along the creeks, from March until May. Castilleia parviflora Bong, var. Douglasii Jepson, Indian Paint Brush-. Frequent on openly wooded hillsides throughout the ridge, from March until May. ^rthocargus faucibarbatus Gray. Restricted to the serpentine meadow, where it is abundant in April and May. Orthocarpus densiflorus Benth. Owl's Clover. Very abundent in fields and on open hillsides from March until May. Orthoc_arpus purjpur a seen s Benth. Sscobita. Similar to the above species in distribution, 68

abundance, and time of flowering. s pilosus Gray. Common on dry open hillsides during August and September.

Pedj^cularis densiflora Benth. Indian Warrior. Frequent on openly wooded hill slopes in February and March.

Plantaginaceae Plantago major L. Common Plantain.

Rare; one plant found near the lake in August. Plantago .lanceolata L. Ribwort; English Plantain. Common in the area around the lake in July and August Plantago erecta Morri s . Abundant on grassy hillsides and in the serpentine of the meadow from March until May.

Rubiaceae

Gal imp aparine L. Goose Grass. Common in shady, grassy areas from March until May. Galium triflorum Michx. Sweet Bed straw. Frequent in woody thickets and openly forested slopes

in April and May. Galium t ri f idum L. Croup-weed. Frequent in moist areas of shady woods in April and

May. 69

Galium Nuttallii Gray.

Frequent, growing over shrubs in thickets and in the chaparral. It blooms in March and April.

Capri foliaceae Sambucus glauca Nutt. Blue Elderberry.

Abundant in openly wooded areas, at the edges of the chaparral, and along stream banks. The blooming season is from May until September. Symphoricarpos albus (L.) Blake. Snow Berry. Abundant on wooded slopes and along creek banks. It flowers in May and June and the berries ripen in September. Banks, var. Ledebourii. Infrequent along the banks of San Francisquito Creek. March to June. Lonicera hj^LEi^l^ 33ougl . var. californica Jepson. California Honeysuckle. Common along the creeks and on wooded slopes, flov/er- ing in June and July.

Abundant in areas along the roadside. First col lected in July.

Vale ri anace ae

Plectritis macrocera T. & G. 70

Common in fields and. on open hillsides in April and May.

Zl^t^Jis ciliosa Jepson. Very similar to Plectritis macrocera, arid generally found growing with it.

Gompositae

Gichorieae TJrojpapjyus Lindleyi var. leucocarpus Jepson. Frequent in fields and on open hillsides in March and April.

Picris echioides L. Bristly Ox-tongue. Common along roadsides and at the edge of the lake from July to October. Hypochoeris glabra L. Smooth Cat1s-ear. Common in fields and on open slopes in April and

May. Stephanomeria virgata Benth. Infrequent along roadsides, blooming in September and October. Lactuca scariola L. Prickly Lettuce. Rare. One plant found near a building in November. Sonchus oderaceus L. Common Sow-thistle. Common along roadsides and at. the edge of the lake.

It was observed blooming throughout the entire period of the survey. 71

asper L. Prickly Sow-thistle. Similar to the preceding species in abundance, distribution, and period of flowering, and often found growing with it.

M2§.®rJL§ ££gndl_flora (Nutt.) Greene. Common on open or openly wooded slopes in May and June .

Hieracium albiflorum Rook. Abundant on both openly and heavily wooded slopes in July and August.

Astereae Grinae_lia rubricaulis DC. Red- stem Grindelia. Common on openly wooded hillsides throughout the ridge in May and June .

Ast^er chilensij? Nees. Common Aster. Frequent on openly wooded slopes from August until

October. ' Coyote Brush,* Chaparral Broom. Abundant in openly wooded areas, along roadsides, and near the edge of the chaparral. Blooms from August through November. Baccharis Douglasii DC. • Common in the area around the lake and along roadsides. August to October.

Inuleae

Kicropus jcalifornicus F. & M. 72

Very abundant on open hillsides during April and May.

Gnapha_lium irurpureuin L. Purple Cudweed. Common on openly wooded slopes in May and June. ^Q^ohalium £.aljus^tre Nutt. Lowland Cudweed. •- Relatively infrequent along the road by the lake in August . Gnaphalium luteo— album L.

Rare; one plant found, flowering along the side of the road above the lake, in November. Gnapha 1 ium ch i 1 ens e Spreng. Cotton-batting Plant.

Frequent on dry, open hillsides from June to August Anaphalis margaritacea (L.) B. & H. Pearly Everlasting. Common on both open and openly wooded hillsides from June to August.

Heliantheae Wyethia a.ngu.sjj^folj.a Nutt. Frequent in open fields. Found blooming in May.

Madieae

Hemizonia cong_esâ var. 3^_zulêjjol_iâ Jepson. Hay field

Tar weed. Extremely abundant on open hillsides and in the serpentine meadow from June to October. Madia madJLOidjss (Nutt.) Greene. Woodland Madia.

Frequent on heavily wooded slopes during May and June 73

£ .ssrtlva Molina. Chile Tarweed. Common along roadsides and on open hillslopes. July and August.

M§£i§. dissj.t^iflora (IMutt.) T. & G. Gumweed. Abundant on "open and openly wooded slopes from May to July.

Ma^ia exlgua (Sm.) Greene.

Frequent on openly wooded hillsides. May and June. Layia ^latyglossa (P. & M.).Gray. Tidy Tips. Abundant in the meadow of the serpentine and confined to that area. April and May. i§jJL§* ±1®£SS5 (Nutt.) T. & G. Infrequent in fields and on the open hillsides, blooming in April and May. L^agoghylla r amo SJLJS aim a Nutt. Common on dry, open hillslopes from the last of May through August, ^hyrachaena mollis Schauer. Blow-wives. Frequent in fields and open slopes during April and

May.

Ambrosieae

Xanthlum c^anajdjense Mill. Cockle Bur.

Common around the xedge of the lake, flowering in July and August and fruiting in October and November. 74

Helenieae • & M- Gold Fields. Abundant in fields and on open hillsides and" in the meadow of the serpentine during April and May. • M.9SPJ^5PJL§. ££&cii®n§. Gray. - Frequent on openly wooded hillslopes in May and June jSriophyllum confertiflorum Gray. Common in openly wooded areas and near the chaparral formation, flowering from May until July. Brlophyirum 1anaturn var. grandif1orum Jepson. Rare. One plant was collected on an openly wooded slope in May. jielenium puberulum DC. Hosilla.

Common along the banks and. in the dry bed of San

Francisquito Creek from July to October.

Anthemideae

Anthemis cotula L. Mayv/eed. Infrequently found in pastures and disturbed areas.

May and June.

4£hi_yj3§. ^y^l^9jJ-J^3 k« var. lanulo_sa Piper. Common Yarrow; Milfoil. \ Abundant plant of the openly v/ooded hillsides, found blooming from April through June. Matricaria jsuavjeoljjis (Pursh.) Buch. Pineapple Weed. Frequent in waste lands, being especially common along roadways. April and May. 75

jLa ,£a_l_ifqrni_ca Less. California Sagebrush; Old Man . Abundant on brushy hillsides throughout the ridge, often growing at the edge of the chaparral. July to November.

fcffit?i§ yjujj^aji?ijs var, heterophy.il a Jepson. California Mugwort . Common along the banks of streams and shady roadsides in July and August.

. aron!coides DC. Infrequent on openly wooded slopes and brush-covered hillsides. May and June. Senecio Brewer! Davy. Pound growing infrequently in openly wooded areas during May and June. Senecio vulgaris L. Common Groundsel. Common in open fields and along roadsides. March end April.

Cynareae Cirsium lanceolatum (L.) Scop. Bull Thistle. Frequent but widely scattered. Found mainly along the edges of roads in brushy areas. June to August. americ_anum Daniels. Rare. One specimen found along a roadside in June. 76

. (Nutt.) Jepson. Pound infrequently on dry, openly wooded slopes of the ridge, from May to July.

Cirsium occidentale var. Coulteri Jepson. Very similar to the preceding type, and .the distribution, abundance, and flowering period are the same.

Garduus tenuiflorus Curt . Frequent plant of disturbed areas. It is found mainly along roadsides in May. me 11 tens is L . Nap a Thi stle; Tocplote. Abundant in fields, on dry, open slopes, and along the roadsides. June to August. Centaurea ssbiWalis L. Yellow Star Thistle; Barnaby's

Thistle. Abundant in the pastures and fields and especially along roadsides. July to October. VII SUMMARY

1. Jasper Ridge is one of the higher foothills of the Santa Cruz Range. It is located in San Mateo County, California, approximately four miles southwest of Stan- ford University. Geologically, the main portion of the ridge is made up of the Chico formation; other less sizeable areas belong in the Santa Clara, Franciscan, and Purissima Formations. An outcrop of seroentine lies between a portion of the Chico and Franciscan Formations. 2. The plants of Jasper Ridge can be divided into three vegetative cornmunities: forest, chaparral, and grassland. The forest is found largely on the steeper northern slopes, the chaparral is mainly on the southwestern and southeastern slopes, and the grasslands are generally in the level places on top of the ridge and on the gently rolling slopes. 5. Within the formations there are associations of plants which are associated with definite topographical features. There are transitional zones between the plants of each proup. 4. The forest plants are characterized by the comparatively large size and the luxuriance of their foli- age; those of the chaparral have extensive root systems, rigid branches, and small, thicl^, heavily cutinized leaves

77 78

The vegetation of the grasslands consists almost entirely of herbs.

5. The survey was conducted during the period between March and December, 1947. A total of 299 species of spermatophytes was collected. VIII

CONCLUSION

The vegetative character of each of the three formations on Jasper.Ridge is influenced to a greater or lesser extent by various ecological factors. Of these, rainfall, fog, and wind may be dismissed as relatively immaterial. In the main, the problem is one of water- balance .

The luxuriant growth of the forests is due to the high humus content and lower temperatures of the soil. These cause a low evaporation rate and consequently there is an ample water supply during the spring months when vegetational activity is at its peak. In the chaparral and grasslands, however, there is a less favorable water-balance. In these areas there is little or no humus in the shallow soil and drainage is often excessive. The soil temperature and evaporation rate are both high and the water supply of the soil is thus decreased. This results in the typical xerophytic, shrubby growth of the chaparral and in the characteristic herbaceous vegetation of the grassland. The only place on the ridge in which the vegetation is affected by the geological formation underlying it is the area in the strip of serpentine. Here there are many outcroppings of rock and the shallow soil has a very

79 80

small amount of humus ana contains minerals detrimental to the growth of meny species. A number of plants, which are tolerant of the toxic minerals present in the soil derived from the serpentine rock, are found in this area and do not grow elsewhere on the ridge. IX BIBLIOGRAPHY

1. Abrams, LeRoy. An Illustrated Flora of the Pacific States. Vol. I. Stanford University. 1923. 2. An Illustrated Flora of the Pacific States. Vol. II. Stanford University. 1944. 3. Barry, Margaret Alice. A Floristic and ideologic Study of Goal Mine Ridge . Contri/butions frora _the

£Hfil®Z .5®£^?!i}55' Vol. 3, No. 1. Stanford University. 1940. 4. Branner, J. C., J. P. Newsom & Ralph Arnold. Santa ^ffi^ Folio. U. S. Geologic Survey. Geol. Folio No. 163. Washington. 1909. 5. Bureau of Soils. Reconnaisance Soil Survey of the San Francisco Bay Region, California. U. S. Dept. of Agriculture. Washington. 1917. 6. Cooper, Wm. S. The Broad-Sc1erophy11 Vegetation of California. Carnegie Institution of Washington, Publication No. 319. 1922. 7. Hitchcock, A. S. Manual of the Grasses of jthe United States. Washington. 1935. 8. Jepson, Willis Linn. A Manual of the Flowering; Plants of California. Berkeley. 1925.