DEVELOPMENT of GROUND COVERS for HIGHWAY SLOPES Development of Ground Covers for Highway Slopes

INVESTIGATION NUMBER 615 FINAL REPORT MAY 1971

-.,:_ TECHNICAL BULLETIN 282 AGRICULTURAL EXPERIMENT STATION

DEVELOPMENT OF GROUND COVERS FOR HIGHWAY SLOPES Development of Ground Covers for Highway Slopes

FINAL REPORT-1971 Investigation No. 615

Albert G. Johnson, Donald B. White, Margaret H. Smithberg, and Leon C. Snyder•

Department of Horticultural Science, University of Minnesota in cooperation with U.S. Department of Transportation, Federal Highway Administration Minnesota Highway Department Minnesota Local Road Research Board

The opinions, findings, and conclusions expressed in this publication are those of the Department of Horticultural Science, University of Minnesota and not necessarily those of the Federal Highway Administration.

* Authors are University of Minnesota personnel: Albert G. Johnson is research associate, University of Minnesota Landscape Arboretum Donald B. White is professor, Horticultural Science Margaret H. Smithberg is associate scientist, Horticultural Science Leon C. Snyder is director, University of Minnesota Landscape Arboretum Table of Contents Page Page Planting of Nursery Stock ...... 44 I. Evaluation Categories ...... 8 Establishment of Plant Materials ...... 45 Maintenance of Plant Materials ...... 45 Availability of Plant Materials ...... 45 II. Evaluation of Plant Materials Evaluation of Plant Materials and Hardiness 29 Tables University of Minnesota Landscape Arboretum 1. Ground covers recommended for use on Evaluations highway slopes in Minnesota ...... 8 Plant Introduction Nursery ...... 30 2. Plants recommended for limited use on Arboretum South Bank Planting ...... 30 Minnesota roadsides ...... 12 Arboretum Service Area Bank Planting ...... 30 3. Plants not recommended or not sufficiently Arboretum Roadside Planting-1966 ...... 30 evaluated for Minnesota roadsides ...... 18 Nursery for Plants of Sandy Acid Soils ...... 31 4. Arboretum bank planting-1963 ...... 30 University of Minnesota Branch Experiment 5. Evaluation of plants in arboretum service area in Station Evaluations 1964 and 1969 (planted with potted stock August 9, 1963) ...... 31 Grand Rapids Loon Lake Plantings ...... 31 6. Relative performance ratings of ground covers after one and three seasons on the Landscape Arboretum Wendigo Slope-Community Park roadside (planted 1966, rated 1967 and 1969) ..... 31 Plantings-1965 ...... 32 7. 1969 evaluation-Loon Lake plantings (planted 1964 Morris Station-1967 ...... 33 and 1965) ...... 32 Crookston Station-1965 ...... 33 8. Iron chlorosis on potential ground cover plants Highway Site Evaluations grown at Crookston, Minnesota, 1967 ...... 33 1-494 Plantings-1963 ...... 33 9. Evaluation of plantings, 1-494, planted 1963, 1964, 1965, and 1966 ...... 34 TH-65 Plantings-Soderville, Anoka County . . . . 36 10. 1969 evaluation of materials planted in 1963 and Cleveland Avenue, Roseville, Ramsey County, 1964 on TH-65 ...... 37 Dwarf Southernwood Plantings ...... 36 Lakeville 1-35 Plantings-1967 ...... 36 11. Performance of selected junipers after 2 years on the Lakeville site: planted 1967 ...... 38 Native Ground Cover Collections ...... 38 12. Germination and ground cover evaluation of Experiments in Propagation and Establishment herbaceous materials: planted 1967 at Lakeville .... 38 Crownvetch ...... 40 13. Performance of deciduous shrub plantings: planted Direct Seeding of Woody Plants 1967 at Lakeville ...... 38 Smooth Sumac ...... 41 14. Rating of Creeping Juniper collected from native Direct Seeding of Smooth Sumac ...... 42 stands after 2 years of growth: planted 1963 ...... 39 Hydroseeding of Smooth Sumac Seed ...... 42 15. Mean ratings for establishment of transplanted seed Direct Seeding of Woody Ground Covers- lings of four Crownvetch varieties: planted May 25, Cannon Falls ...... 42 1967, and rated July 23, 1968 ...... 40 Plant Surveys of Existing Highway Slopes ...... 43 16. Mean heights and widths of four varieties of Crown vetch after one growing season from seed: planted Additional Research Considerations ...... 43 June 1, 1964, scored October 7, 1964 ...... 41 Miscellaneous Small Trees Brought into 17. Ratings of Crownvetch seedlings grown on the Land the Program ...... 43 scape Arboretum slope: planted April 28, 1964, scored September 11, 1966 ...... 41 18. Mean heights and widths of five Crownvetch varieties III. Establishment and Maintenance of Plant Materials grown from seedlings: planted May 9, 1967, Grades and Standards ...... 44 scored July 23, 1968 ...... 41 Source of Plant Materials ...... 44 19. Cannon Falls direct seeding test: plant and mulch Handling of Plant Materials ...... 44 materials used ...... 42 Planting ...... 44 20. Evaluation of small trees for roadside planting . . . . . 43

3 Figures Page Figures Page 1. Zones of plant hardiness in _Mi~nesota from the 31. Cowberry ...... 50 USDA Miscellaneous Publication No. 814, 1960 .... 7 32. Thicket Creeper ...... 51 2. Bearberry ...... · · · · · · · · 46 33. Virginia Creeper ...... 51 3. Crownvetch ...... · · 46 34. Reynoutria Fleeceflower ...... 51 4. Tawny Daylily ...... 46 35. Lilac Honeysuckle ...... 51 5. Redosier Dogwood ...... 46 36. Rush Lespedeza ...... 51 6. Arcadia Juniper ...... 46 37. Sicklepod Milkvetch ...... · 51 7. Skandia Juniper ...... · · · · · · · · · · · · 46 38. India Mockstrawberry ...... 52 8. Creeping Juniper ...... 47 39. Partridgepea ...... 52 9. Japanese Garden Juniper ...... 47 40. Russian Peashrub ...... 52 10. Oldfield or Prostrate Juniper ...... 47 41. Perennial Peavine ...... 52 11. Pfitzer Juniper ...... 47 42. Herbaceous Periwinkle ...... 52 12. Sargent Juniper ...... 47 43. Quicksilver Petunia ...... · · · 52 13. Cicer Milkvetch ...... 47 44. Alaska Phlox ...... · · · · 53 14. Kamchatka Rose ...... 48 45. Maiden Pink ...... · · · · · 53 15. Fragrant Sumac ...... 48 46. Magic Carpet Polygonum ...... · · · · · · 53 16. Smooth Sumac ...... 48 47. Japanese Trailing Raspberry ...... · · · · · · · 53 17. Birdsfoot Trefoil ...... 48 48. Fringed Sage ...... · · · · · · · · · · · · · · · 53 18. Prostrate Alfalfa ...... 48 49. Common Snowberry ...... · · · · 53 19. Pirone Alfalfa ...... 48 50. Dwarf Southernwood ...... · · · · 54 20. Sicklepod Alfalfa ...... 49 51. Billiard Spirea ...... · · · · · · · · · · · · · · · 54 21. Barrenstrawberry ...... 49 52. Dwarf Garland Spirea ...... · · · · · 54 22. Bayberry ...... 49 53. Dwarf Cutleaf Stephanandra ...... · · · · · 54 23. Allegheny Blackberry ...... 49 54. Two-row Stonecrop ...... · · · · · · · · · · · 54 24. Georgia Bushhoneysuckle ...... 49 54 55. Sweetfern ...... · · · · · · · · · · · · · · 25. Dwarf Spring Cinquefoil ...... 49 55 56. Bird Vetch ...... · · · · · · · · · · · 26. Wineleaf Cinquefoil ...... 50 57. Virginsbower ...... · · · · · · · · · · · · · · 55 27. Friedrichseni Cinquefoil ...... 50 58. Wolfberry ...... · · · · · · · · · · · · 55 28. Irving Cinquefoil ...... 50 59. Adamsneedle Yucca ...... · · · · · · · · · · · · · 55 29. White Clover ...... 50 60. 1963 plants on 1-494 in Eden Prairie Township !! 30. Zigzag Clover ...... 50 61. Crownvetch plantings in Landscape Arboretum · · · ·

4 FOREWORD ACKNOWLEDGMENTS This report completes and organizes the research informa Credit is due the following cooperating agencies involved tion generated under Investigation 615: "Development of in supporting and maintaining continued interest in the proj Ground Covers for Highway Slopes." It was written specifically ect: The Minnesota Highway Department, Minnesota Local for highway personnel and citizens who may be interested or in Road Research Board, and the U.S. Department of Transpor volved in establishing ground covers in difficult situations. tation, Federal Highway Administration. The report's main purpose is to summarize findings and de The original interest and efforts of J.H. Swanberg, former velop recommendations from the project research. Deputy Commissioner; H.E. Olson, former Engineer of Road The report is presented in three sections. Section One pre side Development; and P.O. Velz, then Research Engineer, sents recommendations resulting from the research. Section Minnesota Highway Department, deserve recognition. Two develops the research effort and results of investigations. The continued interest of C.K. Preus, Research Coordina Section Three is devoted to general cultural information and tion Engineer; F.C. Fredrickson, Materials Engineer; P.A. maintenance specifications that should be useful to field per Jensen, former Research Engineer; P.J. Diethelm, Research sonnel and administrators who are directly or indirectly in Engineer; W.N. Yoerg, Research Operations Engineer; and vC1lved with highway maintenance situations. B.F. Himmelman, Office Engineer, Minnesota Highway De For purposes of this report, ground covers are defined as partment, in all aspects of the project is gratefully acknowl plant materials, other than turfgrass, capable of providing a edged. Special thanks are due Dr. L.E. Foote, Director of En uniform dense covering over the soil surface and with a root vironmental Services, Minnesota Highway Department, for his system of sufficient density and depth to stabilize the soil on interest and help in many of the problems that inevitably arise which they are planted. In investigations reported here, special in such an undertaking. emphasis has been placed on materials with a full growth The Soil Conservation Service and the Plant Introduction height of 2 feet or less. However, certain materials that offer Stations of the U.S. Department of Agriculture (USDA), ar particularly valuable characteristics but did not fulfill this spe boretums, other institutions, and many interested individuals cification were also considered. contributed greatly to the success of the project through their generosity with plant materials.

5 INTRODUCTION Results This final report of Investigation 615, "Development of Thirty-four vanetJes are recommended for use on Min Ground Covers for Highway Slopes" has been prepared to nesota highway slopes. An additional 71 varieties are recom summarize findings and results of investigations on the use of mended for limited use or experimental planting for further ground cover type plants for Minnesota roadsides. The in evaluation. vestigation was initiated at the request of the Minnesota High Most leguminous species investigated established ~eadily way Department in July 1962. The research program was from seed. Seedings of Milkvetch and Birdsfoot Trefoil re conducted by the Department of Horticultural Science, Agri sulted in excellent cover the first year from seeding. Crown cultural Experiment Station, University of Minnesota for the vetch, however, took two to several years to become estab Minnesota Highway Department, Minnesota Local Road Re lished from seed, or one season from transplants. search Board, and the U.S. Department of Transportation, Evergreen ground covers (junipers) established well using Federal Highway Administration. balled and burlapped or container grown stock 2-3 years old. The study was initiated only after it was determined there Liners ( one year rooted cuttings) proved unsatisfactory under was insufficient information on ground cover plants and their the limited cultural conditions on highway sites. Direct seed use to develop recommendations for highway situations. The ing of woody ground covers did not yield satisfactory results. primary purpose of the investigations was to develop materials Conclusions and Recommendations that would enhance safety and beauty, increase the effec tiveness of erosion control, and reduce maintenance costs on 1. It was concluded that use of selected ground cover Minnesota highways. plants may be a practical alternative to grass on bridge abut The objectives of the investigation follow: ments, in certain urban situations, and on steep highway slopes 1. Obtain, develop, and evaluate ground covers for Min under strict maintenance regimes. nesota highway roadsides. 2. It is recommended that provision be made to ensure 2. Survey, collect, and test native plant species potentially further evaluation of plant materials listed in the limited use useful as ground covers; study their ecological requirements category and noted in table 3 as needing more study. and determine their applicability to highway slope planting. 3. It is also evident that additional research is needed in ~- Study t_he problems of slope planting in the field, in the areas of salt tolerance and establishment and maintenance cludmg estabhshment and maintenance. of native ground covers. 4. S!udy. the cultu:e, propagation, hardiness, longevity, and ava1lab1hty of species recommended for slope planting. HARDINESS ZONE MAPS Each species in this report has been designated with a hardiness rating that corresponds to the map developed by the SUMMARY USDA ( 1960) and refined for Minnesota (figure 1). Purpose In this report Minnesota is divided into three hardiness zones. Plants are hardy in the zone designated and any zone The purpose of the investigation was to research the cul with a higher number. ture, h~rdi~~ss, longevity, propagation, maintenance, and gen Occasionally very local situations ( conditions approximat e~al smtab1hty of plant materials for use as ground covers on ing a milder climate) may exist where plants may survive in highway slopes in Minnesota. colder zones. The only way to ascertain these situations is by Procedures trial and error or detailed study. Plants can be recommended for use in colder than normal zones only in extraordinary The study w_as initiated in 1?62. During the next 6 years situations. over ~00 a~cess10ns ot plant_s w1~h ground covering potential were mvest1,?ated at the Umv~rs1ty of Minnesota Landscape SALT TOLERANCE Arboretum. · ~!ants were ac~mred from the nursery industry, foreign. countnes, USDA S01I Conservation Service, Plant Jn The use of salt for ice and snow removal on highways troduct!on ~tat1ons, and by collection from the wild. Initial leads to injury to roadside vegetation. Plant species vary in evalu~tion mcluded hardiness, habit of growth, propagation their ability to tolerate salts in various concentrations. Selec establishment, and cultural limitations. ' tion and use of salt tolerant plants in vulnerable situations of _The materials were also evaluated at University branch ex fers a partial solution to the problem. penment stations in M_orris: Crookston, and Grand Rapids, Comparatively little information is available concerning and on selected roadside s!tes. Plantings were designed to the salt tolerance of most of the ground cover plants covered evalu~te metho_ds of establishment and maintenance under in this report. No research on this aspect of the use of gro~nd roadside cond1t10ns. cover plants was conducted in connection with Investigat10n

* For brevity, often referred to later in text as Landscape Arboretum.

6 \

Ol'HO•"'ATCUOIG[Of OY[UGI UMYAL ll1H,10W n11-i:u1~~[$ '°" UG" fo,,E D -~O"TO·•O" D ~ ·lO"TO·Z0" -ZO"T0·10"D

D ,0•10 zo• c:J 10-10)0"0- ~0·10 oo• -

Figure 1. Zones of plant hardiness in Minnesota from the United States Department of Agriculture Miscellaneous Publication No. 814, 1960 (U.S. map above)

7 615, so all opinions are based on other reports or in a few Table 1. Ground covers recommended for use on high cases on observation of apparent salt tolerance. In the absence way slopes in Minnesota of precise information, salt tolerance is indicated in tables 1 and 2 simply as: susceptible to salt injury (-), salt tolerant ( + ), or unknown (U). BEARBERRY (Arctostaphylos uva-ursi) (figure 2) Zone 2 Plant Description: A prostrate evergreen trailing shrub form ABSTRACT ing a mat-like cover with small leaves and white inconspicu ous flowers. To 8 inches. Over 500 different accessions of woody and herbaceous Range: Throughout northern part of the world-native to plant materials were studied to determine their suitability for northern Minnesota. use as ground covers on highway slopes in Minnesota. Plant materials are separated according to performance: Site Tolerance: Full sun or partial shade, poor acidic (sandy 34 are recommended for use and 71 are recommended for or rocky) soils. limited use in Minnesota. Plants not recommended are also re Salt Tolerance: +. 1 viewed. Plant descriptions, geographic range, hardiness, site limi Propagation: Grown from cuttings and established in pots. tations, salt tolerance, propagation, availability, establishment, Can be difficult to transplant. Sods of wild material may be culture, and maintenance requirements of the recommended placed directly on slopes. Cuttings of mature wood or early materials are discussed. spring cuttings of rooted stem sections. Several cultural investigations associated with the 6-year Establishment and Culture: Grown from transplants or rooted program are also reported. cuttings. Plant 1 foot apart ( 1,000 per 1,000 square feet). More research needed on establishment requirements. A vigorous spreader requiring no attention once established. The Matter of Names No insect or disease problems. The names of plants in this report, with few exceptions, Availability: Not readily available. Should be contract grown. are those in the current horticultural vernacular in Minnesota and surrounding states. The names largely correspond to those CROWNVETCH ( C oronilla varia) ( figure 3) of "Standardized Plant Names," (1942), except where too Zone 2 cumbersome or unrealistic to be acceptable. Plant Description: Perennial legume, 1-2 feet tall. One plant Common names are used with botanical names in the can cover 6 feet of ground. Plants mound up and form a tables to avoid misinterpretation and identification problems. dense ground cover. Pink flowers. By their nature, common names are unstable and often local in application. A given species may have several common Range: Native of Europe and Asia but escaped along road names or a name that is applied to unrelated species in differ sides and fields in Northeastern and Central U.S. ent parts of the country. Site Tolerance: Best in full sun but tolerates limited shade. The common names of plants are capitalized throughout Good in dry infertile situations and on banks. Faster grow this report for clarity and emphasis. ing with adequate moisture after establishment. Does not tolerate less than 6.5 pH-prefers circumneutral soils. Salt Tolerance: U. Propagation: Division of plants or roots or by seed. Establishment and Culture: Establish by seed, crowns or transplanting of seedlings. Slow to establish and poor com petitor first year but produces excellent cover by second Evaluation Categories 2 I. or third season. Use with nurse crop of red clover, K 31 fescue or ryegrass is suggested at 20 pounds/acre Crown vetch to 25 pounds/acre nurse crop. If using plants, space The evaluations are presented in three different categories: ( 1) ground covers recommended, ( table 1 ) , plants warranting 1 ½ feet apart ( 440 plants per 1,000 square feet). consideration for extensive use within the range of conditions Availability: At most commercial seed houses. prescribed; ( 2) plants recommended for limited use, ( table 2), Special inoculants should be employed when planting seed plants with specific limitations or local adaptability; and (3) ( obtained when purchasing seed) to ensure proper growth plants not reco:'11mended or not sufficiently evaluated, (table in the absence of heavy nitrogen fertilization. With properly 3 >'. plants lackmg hardiness or adaptability to highway con d1t10ns. inoculated seed, a fertilizer ration of 1-2-2 should be used at rates no more than 60 pounds actual nitrogen per acre. Recommended varieties are listed with brief annotations to Holds steep banks with large root system and heavy cover describe t~e ~haracter, application, and limitations of the plants. of leaves, which even in winter offer good soil protect1~n. The _hm1ted recommendation category includes some Recommended on clay banks where rough cover is permis plants with landscape value and unquestionable merit as sible. ground covers, but less successful under Minnesota conditions tha!1 those &iven full recommendation. In the right situation a given species_ may equal or exceed the performance of some DAYLILY, TAWNY (Hemerocallis fulva) (figure 4) Zone 2 of the more highly recommended varieties. This category in Plant Description: Hardy perennial lily-like plants with long cludes many plants that need further evaluation before a firm leaves and single or double flowers. Height to 3 feet. Long recommendation can be made. leaves produce heavy ground cover. Species unsatisfactory for use under Minnesota roadside conditions are those not recommended. Some in this category Range: Native of Asia but widely naturalized in the United may be excellent ground covers under cultivated conditions or States. in warmer climates. Site Tolerance: Adapted to a wide range of well-drained soils.

1 + = tolerant, U = tolerance unknown, - = intolerant. 2 A companion crop which germinates early and aids in initial soil stabilization.

8 Table 1. Ground covers recommended for use on high Suggested for mass plantings on banks. way slopes in Minnesota (continued) Availability: Both available-Skandia not as common as Ar cadia.

Salt Tolerance: + Propagation: By division of root stock. Easily increased. Seeds JUNIPER, CREEPING (Juniperus horiwntalis) (figure 8) rarely produced. Zone 2 Establishment and Culture: Easily established from crowns. Plant Description: Prostrate and creeping evergreen forming Space 1½ feet apart ( 440 plants per 1,000 square feet). low mats. Produces long runners which may root. Turns Little maintenance required. purplish color in winter. To 15 inches. Availability: Readily available from nurseries. Range: North America from Nova Scotia west to Montana. Found on sea cliffs and gravelly slopes. DOGWOOD, REDOSIER (Cornus stolonifera) (figure 5) Site Tolerance: Prefers dry sandy or rocky soils. Tolerates sun Zone 2 or partial shade. Tolerant of both acid and alkaline soils. Plant Description: A spreading shrub to 10 feet. Through the Salt Tolerance: +. program a new lower-growing variety was introduced called Propagation: Possible from seed. If growing varieties, by cut 'Isanti.' Its inclusion as a ground cover is based on its height tings in August-October or by layering. Roots easily. (under 6 feet) and its ability to spread by stolons. Establishment and Culture: Establish by transplants of balled Range: Throughout North America except for the southeast and burlapped stock. Plant 3 feet apart ( 110 per 1,000 ern United States. square feet). Once established requires little attention. Can Site Tolerance: Widely adapted to all but very dry sites; most be cut back and plants will become more heavily branched. common on moist soils. Availability: Many of the varieties in the following list (and Salt Tolerance: U. especially Bar Harbor, Waukegan, and Hughes) are com monly sold in nurseries. Propagation: Cuttings, both hard and softwood. Cuttings root easily. Good for banks. The ground covering ability of this plant is superb, but most wild forms are of comparatively slow Establishment and Culture: Established by transplants. Plant growth. Numerous varieties of this plant are in the nursery 3 feet apart (110 per 1,000 square feet). No special cultur trade and vary considerably in plant form, color, foliage, tex al requirements needed. ture, and vigor. The following juniper varieties from the pro Availability: Isanti, the low-growing form, is beginning to be gram are rated highly. available. Propagation material can be supplied to nurseries. Isanti is a very dense shrub ideal for screening effects and hedges. It has the same cultural requirements as ordinary Redosier Dogwood. This is one of the significant new vari eties developed in the program and the only one sufficiently Varieties of Creeping Juniper tested to be named and introduced to the nursery trade. Name Zone Height Description JUNIPERS JUNIPER, ADMIRABILIS 2 1' practically same The junipers comprise a large group of evergreen trees and (Juniperus horiwntalis as creeping shrubs, some of which are prostrate in habit. The low, pros 'Admirabilis') juniper trate types are of primary interest for ground covers. Varie ties and selections from five species have been included in JUNIPER, ADPRESSED 2 6" lower than these investigations. (Juniperus horiwntalis creeping juniper 'Adpressa')

JUNIPER, ARCADIA and JUNIPER, SKANDIA (Juni JUNIPER, BAR HARBOR 1 l' steel-blue perus sabina 'Arcadia' and 'Skandia') (figures 6 and 7) Zone (Juniperus horizontalis needles, 2 'Bar Harbor') more compact 1' practically same, Plant Description: These two junipers are low-growing selec JUNIPER, BLUE CREEPING 2 (Juniperus horiwntalis but bluer tions of Savin Juniper. Skandia is the lower growing ( 1 needles branches and dense form. They are markedly hardier than glauca) foot) while Arcadia is taller ( 1 ½ feet) , with arching JUNIPER, BLUE HORIZON 2 1' same as above branches and dense form. They are markedly hardier than (Juniperus horiwntalis typical Savin Juniper, which is of borderline hardiness in 'Blue Horizon') Minnesota. JUNIPER, BLUE RUG 2 1' good, spreading, Ran~e: Both varieties originated in Canada from seed ob (Juniperus horiwntalis 'Blue fast-growing tamed from the Ural Mountains, U.S.S.R. Cultivated in Rug - sometimes sold as variety U.S. and Canada. 'Wiltoni,' 'Wilton Carpet') Site Tolerance: Quite intolerant of poorly drained soils. Ac- cepts a broad pH range. JUNIPER, FILICINUS- 2 1' same as MINIMUS creeping juniper Salt Tolerance: U. (Juniperus horiwntalis essentially Propagation: By cuttings. 'Filicinus-Minimus') Establishment and Culture: Transplants of balled and bur JUNIPER, FLAT CREEPING 2 1' same as above lapped stock. Plant 2 feet apart (250 per 1,000 square (Juniperus horiwntalis feet). Maintenance minimal once established. 'Glomerata')

9 Table 1. Ground covers recommended for use on high JUNIPER, PFITZER (Juniperus chinensis 'Pfitzeriana') (fig way slopes in Minnesota (continued) ure 11) Zone 3 Plant Description: A shrubby juniper of flat-topped broadly Name Zone Height Description pyramidal form, much used as a landscape material. In Minnesota it reaches 4-5 feet in height but is often lower. JUNIPER, HUGHES 2 l' one of fastest Branches spread outward and upward and branchlets droop. (Juniperus horizontalis 'Hughes') growing varieties Site Tolerance: Widely adapted to a range of soils if well with good form drained. and color Salt Tolerance: U. JUNIPER, LIVIDIS 2 l' good color and Propagation: By cuttings. (luniperus horizontalis 'Lividis') form Establishment and Culture: Establish from transplants, balled JUNIPER, MARSHALL 2 l' same as above and burlapped or container grown for general landscape (Juniperus horizonta/is 'Marshall') use. Varieties of Pfitzer Juniper can be used in the same JUNIPER, WAUKEGAN 2 l' very good long- manner as Pfitzer where warranted. (Juniperus horizonta/is 'Douglasii') established var- Availability: Commonly available commercially. iety, blue in Varieties: summer, pur- pie in winter COMPACT PFITZER JUNIPER (Juniperus chinensis 'Pfitz eriana Compacta') JUNIPER, JAPANESE GARDEN (Juniperus procumbens) (figure 9) Zone 3 lhree-four feet in height, somewhat slower in growth and more dense than Pfitzer. Branches horizontal at 1 foot Plant Description: Compact prostrate spreading juniper with above ground. Purple in winter. Establish from transplants. short bluish green, sharp-pointed leaves. Height 1 foot. ARCTIC PFITZER JUNIPER (Juniperus chinensis 'Arctic Range: Native of Japan, long cultivated in United States. Pfitzer') Site Tolerance: Well-drained soils and circumneutral to alka- Four feet in height. Similar in form to Pfitzer w'.th bluish cast line in pH. to foliage. Establish from transplants. Salt Tolerance: U. Propagation: Readily propagated by cuttings or seed. BLUE FFITZER JUNIPER (Juniperus C::inensis 'Blue Pfitzer') Establishment and Culture: Transplant of balled and burlapped stock. Plant 2 ½ feet apart (120 per 1,000 square Six feet in height. Similar to Pfitzer but blue. Establish from feet). Needs no special culture. transplants. Availability: Readily available commercially. This is one of the finest appearing junipers. It hugs the ground JUNIPER, SARGENT (Juniperus chinensis 'Sargenti') (fig closely producing a neat compact appearance. A dwarf form, ure 12) Zone 3 variety 'Nana' is smaller but too slow in growth for highway Plant Description: A low prostrate shrub-1 foot in height- planting recommendation. stems prostrate with upright branches, eventually forms dense broad mass. Adult leaves gray-green. JUNIPER, OLDFIELD, or PROSTRATE (Juniperus com Range: From Kurile Islands and Sakhalin, cultivated in Nor munis depressa) (figure 10) Zone 3 thern U.S. Site Tolerance: Adapted to wide range of well drained soils. Plant Description: Low evergreen shrub to 3 feet high and Useful only in southern Minnesota. several feet wide. Turns purplish-yellow in winter. Salt Tolerance: U. Range: From Newfoundland west to Minnesota. In Minnesota occurs along steep bluffs, river bottoms, throughout state Establishment and Culture: Establish from transplants. Plant except in the southwest prairie region. 2½ feet apart (200 per 1,000 square feet). No special cul ture. Site Tolerance: Tolerates dry, rocky, and sandy soils-rather broadly site tolerant. Propagation: By cuttings or by seed. Availability: Fairly common in the nursery trade. Salt Tolerance: U. Propagation: By cuttings in fall or winter and also by seed. MILKVETCH, CICER (Astragalus cicer) (figure 13) Establishment and Culture: By transplants of balled and bur- Zone 3 lapp~d stock-best when young. Plant 3½ feet apart (ap proximately 100 per 1,000 square feet). Needs little atten Plant Description: Low-growing perennial legume-to 2 feet tion. May be sheared. in height. Looks somewhat like Crownvetch-somewhat viny. Inconspicuous yellowish-white flowers. Availability: Some cultivated varieties are available commercially. Range: From Europe but grown occasionally in the U.S. Site Tolerance: Tolerated circumneutral to alkaline soils

10 Table 1. Ground covers recommended for use on high Propagation: By seed or by root cuttings. way slopes in Minnesota (continued) Establishment and Culture: Establish by transplants. Plant 2-3 feet apart ( 200 per 1,000 square feet). Once established no maintenance needed. Establishment and Culture: Establish by seeding. No main tenance required after establishment. Availability: Commercially available on a limited scale. Has the ability to invade and occupy poor soils producing an Availability: Limited, but should become more available in open stand that permits grasses and other plants to grow be future. neath. Excellent species for areas to be taken out of mainten Cicer Milkvetch is recommended as a bank stabilizing mater ance. A closely related species, Shining Sumac (Rhus copal ial. It establishes more quickly than Crownvetch and produces lina) also performed well in nursery plantings. It succeeds a plant of about equal size. Longevity in Minnesota is at least well in dry soil. Outstanding, with dark green glossy foliage. 5 years. Special bacterial inoculant must be used with the mil kvetches. TREFOIL, BIRDSFOOT (Lotus corniculatus) (figure 17) Zone 3 ROSE, KAMCHATKA (Rosa amblyotis) (figure 14) Zone 2 Plant Description: Perennial legume, to 1 foot, but often pros Plant Description: Shrub rose of vigorous suckering habit. trate in habit, as with Empire variety. One plant covers 2½ Spreads rapidly by suckering from roots. To 3 feet. feet. Small yellow flowers. Range: Kamchatka. Adapted throughout Minnesota. Range: Native of Europe but has escaped and is found on roadsides and pastures throughout northern and central Site Tolerance: Most well-drained soils. North America. Salt Tolerance: U. Site Tolerance: Does well in poor soils, very drought and heat Propagation: By seeds, cuttings, or division. resistant. Can grow in pH range of 4.4-7.9. Tolerates both dry and moist situations. Establishment and Culture: Establish by transplants. Plant 3 feet apart ( 110 per 1,000 square feet). No special culture. Salt Tolerance: +. Availability: Will have to be contract grown as not commer Propagation: By seed, by crown division, and by cuttings. cially available. Establishment and Culture: Plant at depth of ¼ to ½ inch. If plants, plant 1 foot apart (1,000 per 1,000 square feet). SUMAC, FRAGRANT (Rhus aromatica) (figure 15) Needs inoculum, as do all legumes. Fertilizer ratios sug Zone 3 gested are: 0-10-30 or 1-2-2. May be a poor competitor during establishment and weed control measures should be Plant Description: A woody shrub of dense branching habit. incorporated, such as TCA at 8 pounds/acre, Dalapon at Leaves small and trifoliate. Reaches 6 feet on good soils. 4 pounds/acre or 2,4-DB at ½ pound/acre. Nurse crops Range: Eastern United States except coastal region. recommended are Alta Fescue, Ryegrass, or Oats. Best when summer seeded. Can be mowed. Site Tolerance: Shows wide tolerance of dry soils. Availability: Empire readily available, with inoculant, at seed Salt Tolerance: +. houses. Propagation: By seeds or root cuttings. A hardy rather trailing plant for covering dry banks through Establishment and Culture: Establish with transplants. Plant out state. 2-3 feet apart (200 per 1,000 square feet). Little mainten Birdsfoot Trefoil is a plant coming into general use as a forage ance. and pasture legume. The principal forage type is the tall upright Availability: Not commonly available and will have to be con variety Viking. Empire is a pasture form varying from nearly tract grown. prostrate to upright. Several selections are on trial but are not yet commercially available. Covers dry banks and slopes with a low scrambling type cover. Similar to Skunkbush (R. trilobata). Varieties: CILIATE BIRDSFOOT TREFOIL (Lotus corniculatus cili atus) SUMAC, SMOOTH (Rhus glabra) (figure 16) Zone 2 Practically the same as Birdsfoot Trefoil but of lower habit Plant Description: A woody shrub of open coarsely branching than Viking or Empire. habit, spreads by underground stems. Usually under 10 feet, on poor sites often much less. Colorful leaves in fall. ELLIOTT'S BIRDSFOOT TREFOIL (Lotus corniculatus "Elliott's Strain") Range: Throughout United States-in Minnesota on dry sites especially. A low-growing selection of Empire. Site Tolerance: A wide variety of soils including sandy gravel LEO BIRDSFOOT TREFOIL (Lotus corniculatus 'Leo') ly knolls-both sun and partial shade. A new selection from Canada. Of superior seedling vigor to Salt Tolerance: +. Empire but not sufficiently tested.

11 (

Table 2. Plants recommended for limited use on Minnesota roadsides

Plant Plant Salt Evaluation, comments, and Name zone height Spacingec Type tolerance* availability

ALFALFA, PROSTRATE (figure 18) 3 1½' herbt + Spreads rapidly. Of initial promise, (M edicago saliva form) Not generally available.

ALFALFA, CARSTIEN 3 1' 1' herbt + Clonally propagated selection with (M edicago carstiensis) fine textured foliage. Could be useful on limited areas. Establish by rooted cuttings or division. Con- tract grown.

ALFALFA, PIRONE (figure 19) 3 1' herbt + Performed well in early evaluation. (Medicago pironae) Continues to perform well on alkaline soils at Crookston. Full sun. Establish from seed.

ALFALFA, SICKLEPOD (figure 20) 3 3' 1' herbt + This alfalfa has performed well (Medicago falcata) only on barren glacial till. Estab- lish from seed or plants. Not commonly available.

BARBERRY, DWARF JAPANESE 4 2' 1-1½' woody u Ornamental - may h::.ve some (Berberis thunbergi minor) value under culitivated conditions. Establish from transplants. Avail- able.

BARRENSTRAWBERRY (figure 21) 2 6" 1' herbt u A native strawberry-like plant (Waldsteinia fragarioides) adapted to dry sandy wils. Yell ow flowers. Needs further evaluation. Acidic to circumneutral soils, full sun or shade. Establish with transplants. Not readily available. I ~ BAYBERRY (figure 22) 3 3' 2' semi Valuable semi-evergreen. Acidic to , (Myrica pensylvanica) + evergreen circumneutral saline soils, full sun. shrub Readily available.

BITTERSWEET, ORIENTAL 4 2' 2' woody u For use on banks with good soil in (Celastrus orbiculata) vine southern Minnesota. Must be contracted.

BLACKBERRY,ALLEGHENY 3 2-3' 2' decumbent u Of some value where a scrambling (figure 23) woody shrub thorny plant can be used. Adapted (Rubus allegheniensis) to many soils. Available from wild stock. Propagate from root cuttings.

\ ', BLUEBERRY, LOWBUSH 2 2' 1½' woody u Native low shrub, persistent once it (Vaccinium angustifolium) is established. Requires moisture to grow well. For use in mixed vegetation. Acidic soils, full sun or part , shade. Available.

• Spacing at planting time in intervals. 1 foot apart= 1,000 plants/1,000 square feet 2 feet apart= 250 plants/1,000 square feet 3 feet apart = ll0 plants/1,000 square feet t Herbaceous or nonwoody *+ = tolerant, U = tolerance unknown, - = susceptible. §=annual

12 Table 2. Plants recommended for limited use on Minnesota roadsides (continued)

Plant Plant Salt Evaluation, comments, and Name zone height Spacing* Type tolerance:!: availability

BUSHHONEYSUCKLE, DWARF 2 2-3' l½-2' woody u Recommended for dry banks. A (Diervilla lonicera) native species found on acid and circumneutral soils. Tolerates shade and full sun. Inconspicuous flowers. Establish from transplants. Will have to be contracted.

BUSHHONEYSUCKLE, GEORGIA 3 4-5' 2½-3' woody u Recommended for similar situa- (figure 24) tions as Dwarf Bushhoneysuckle, (Diervilla rivularis) but is more vigorous. Available.

BUSHHONEYSUCKLE, SOUTHERN 3 4-5' 2½-3' woody u Recommended for similar situations (Diervilla sessilifolia) as Georgia. More vigorous than Dwarf Bushhoneysuckle. Avail- able.

CINQUEFOIL, DWARF SPRING 3 6" 1' herbt u Suitable only to fertile cultivated (figure 25) situations. Attractive plant hugging (Potentil/a verna 'Nana') ground. Establish from transplants. Contract grown.

CINQUEFOIL, CINNAMONLEAF 4 6" 1' herbt u Vigorous, rather fine-textured. Not (Potentilla cinnafolia) adequately evaluated. Worthy of further observation. Limited availability.

CINQUEFOIL, WINELEAF (figure 26) 2 6-12" 1' evergreen + Very attractive native evergreen (Potentilla tridentata) ground cover adapted to poor rocky and sandy soils. Available locally.

CINQUEFOIL, SHRUBBY 3 1-3' 2½' woody u All Shrubby Cinquefoil cultivars (Potentilla fruticosa) are potentially useful, white to ye!- Varieties: low flowers, silvery foliage. More Forresti adapted to mass planting effects Friedrichseni (figure 27) than ground cover. Circumneutral Gold Drop to alkaline soils, full sun. Particu- Irving ( figure 28) larly adapted to alkaline soils. Es- White Gold tablish from transplants. Available.

CLOVER, ALSIKE 3 1½' 1' herb-r Not reliable on perennial basis. Per- (Trifolium hybridum) sists during wet seasons - declines in dry years. May be used in grass seeding mixtures. Available.

CLOVER, RABBITFOOT 3 1' 1' herb-r + Suited to dry soils. Common on (Trifolium arvense) highway shoulders in northern Minnesota. Acidic to circumneutral sandy soils, full sun. Establish from seed. Available.

CLOVER, RED 3 2-3' 1' herbt A vigorous clover of value mixed (Trifolium pratense) with grass species. Establish from seed. Available.

CLOVER, WHITE (figure 29) 3 1½' 1' herbt Not as vigorous as Alsike Clover. (Trifolium repens) Available.

13 Table 2. Plants recommended for limited use on Minnesota roadsides (continued)

Plant Plant Salt Evaluation, comments, and Name zone height Spacing* Type tolerance* availability

CLOVER, ZIGZAG (figure 30) 4 1' 1' herbt u Spreading clover with some prom- (Trifolium medium) ise as highway material. Performed well in limited plantings. Needs further evaluation. Must be contract grown.

CORALBERRY, INDIANCURRANT 2 3' 2' woody u Similar to W olfberry but somewhat (Symphoricarpos orbiculatus) smaller. Same application. Acid to somewhat alkaline soils, full sun. Establish from transplants. Avail- able. Don't use hybrids, e.g., Chen- aults.

COWBERRY (figure 31) 2 1' 1' woody + A broadleaf evergreen of some (Vaccinium vitis-idaea) evergreen potential on acid soils. Shiny dark shrub leaves make the plant very attractive. A rare native of northern Minnesota. Acid soils and full sun. Must be contract grown.

CREEPER, THICKET (figure 32) 3 1' l½-2' woody u Native deciduous vine adapted to (Parthenocissus inserta) shady conditions. Does not result in uniform dense cover. Will climb. Must be contracted.

CREEPER, VIRGINIA (figure 33) 4 1' l½-2' woody + Closely related to Thicket Creeper (Parthenocissus quinquefolia) but more vigorous. Deciduous vine - potential use on shaded banks. Will climb to 50 feet. Es- tablish by transplant. Engelmann variety available.

FLEECEFLOWER, LOW JAPANESE 4 3' 1½' herbt u Very vigorous, strongly spreading (Polygonum cuspidatum compactum) once plant is established. Tops killed by frost. Can become nuisance in gardens. Available.

FLEECEFLOWER, REYNOUTRIA 4 2-3' 1½' herbt + Attractive pink flowering, vigorous (figure 34) and competitive. Once established (Polygonum reynoutria) will crowd out most weeds. Tops killed back by frost. Establish by pot grown plants. Needs further evaluation. Available.

GOATSRUE 4 4' herbt u Tolerates highly alkaline soils. Stiff (Galega officinalis) upright stems. May be of value on tight, high pH soil situations.

HONEYSUCKLE, LILAC (figure 35) 4 4' 1½-2' scrambling u Recommended as promising dense (Lonicera syringantha) shrub shrub. Performed well in nursery tests. Not adequately tried on roadsides. Establish from transplants. Must be contract grown.

JUNIPER, SAN JOSE 4 1' 2-3' woody u Very low-growing. Needs further (Juniperus chinensis 'San Jose') evergreen evaluation. Not too commonly available.

14 Table 2. Plants recommended for limited use on Minnesota roadsides (continued)

Plant Plant Salt Evaluation, comments, and Name zone height Spacing* Type tolerancet availability

JUNIPER, SPREADING PROSTRATE 2 2' 2-3' woody u Spreading form. Of possible use - (Juniperus communis depressa evergreen needs further evaluation. Not too 'Effusa') commonly available.

LESPEDEZA, RUSH (figure 36) 4 3' herbt u Provides good cover, but turns (Lespedeza hedysaroides) brown at first frost. Crownvetch or Cicer Milkvetch superior for ground cover purposes. Establish from seed. Must be contract grown. Seed from USDA Soil Conservation Service (SCS).

LESPEDEZA, SCHIMID 4 2-3' herbt u Same as Rush Lespedeza. Seed from (Lespdeza daurica schimidae) SCS.

MILKVETCH, SICKLEPOD (figure 37) 3 3' herbt + Vigorous on some sites but does (Astragalus falcatus) not produce as good a cover as Cicer Milkvetch. Establish from seed. Must be contract grown.

M0CKSTRA WBERRY, INDIA 3 6" 1' herbt u Spreading strawberry-like plant (figure 38) with possible limited value. Mostly (Duchesnia indica) garden ornamental. Acid to circumneutral soils. Establish from stolons. Availability limited.

PARTRIDGEPEA (figure 39) § 2' annual u For use as temporary cover on (Cassia f asciculata) sandy soils. Native legume. Estab- lish from seed. Available.

PEASHRUB, RUSSIAN (figure 40) 3 6' 2-3' woody u Suited for use on long slopes or (Caragana frutex) where large size is not limiting factor. Establish with transplants. Available.

PEA VINE, PERENNIAL ( figure 41) 3 3' vine u Perennial vine - good for initial (Lathyrus latifolius) cover. Toxic to cattle. Available.

PERIWINKLE HERBACEOUS 4 1' 1' herbt u Suggested for trial only in pro- (figure 42) ' evergreen tected places. Establish from trans- /Vinca herbacea) vine plants or sods. Available.

PETUNIA, QUICKSILVER (figure 43) § 8" herbt u Has reseeded itself remarkably in (Petunia parviflora 'Quicksilver') the Crookston area. Produces a mounded solid cover persisting until cold weather. Small red flowers throughout season. Seed may be difficult to acquire.

PHLOX, ALASKA (figure 44) 3 6" 1' herbt u Compact dark-green, evergreen- /Phlox borealis) evergreen creeping phlox. Produces dense mat with colorful pink flowers under fertile semicultivated conditions. Circumneutral soils, full sun, ·or part shade. Establishment by transplants. Must be contract grown.

15 Table 2. Plants recommended for limited use on Minnesota roadsides (continued)

Plant Plant Salt Evaluation, comments, and Name zone height Spacing"' Type tolerance:j: availability

PHLOX, AMOENA 3 6" 1' herbt u Attractive creeping phlox with col- (Phlox amoena) semi- orful lavender bloom. Produces evergreen dense matted ground cover in fertile semicultivated situations. Estab- lish by transplants. Must be contract grown.

PHLOX,BLUE 4 1' 1' herbt u Native phlox, occasionally invades (Phlox divaricata) roadsides with other native plants, but does not produce a mat-like cover. Must be contract grown.

PINK, MAIDEN (figure 45) 3 1' 1' herbt u An excellent ornamental garden (Dianthus deltoides) ground cover - may be suited to limited use in areas permitting high maintenance. Establish with transplants. Available.

POLYGONUM, MAGIC CARPET § 4" herbt u A creeping annual which reseeds. (figure 46) annual May have some value in temporary (Polygonum capitatum 'Magic Carpet') plantings. Establish - seed. Available.

RASPBERRY, JAPANESE TRAILING 3 3' 2' woody u Hardy trailing ground cover for (figure 47) fertile sites with adequate moisture. (Rubus parvifolius) Establish from transplants. Soil Conservation Service has basic stock.

SAGE, FRINGED (figure 48) 2 l½' 1' herbt u Limited value on dry sites. A native (Artemisia frigida) species tolerant of alkaline soils. Needs full sun. Establish from transplants. Must be contract grown.

SNOWBERRY, COMMON (figure 49) 3 4' 3' woody + Not adequately tested- similar to (Symphoricarpos a/bus) wolfberry. Establish from transplants. Available.

SOUTHERNWOOD, DWARF (figure 50) 3 1-3' l½-2' semi- + Requires reasonably fertile soils - (Artemisia abrotanum 'Nana') evergreen tolerates alkaline conditions. Re- quires little care and may be c~t back. Doesn't persist on poor sites. Some dying out due to disease. Must be contract grown.

SPEEDWELL, DRUG 3 1' 1' herbt u Hardy plant adapted to moist sandy (Veronica officinalis) perennial slopes. Remains green und~r snow. Acidic to circumneutral s01ls, full sun or shade. Naturalized in no~thern Minnesota. Limited aggressive character. Establish from transplants. Available.

SPEEDWELL, GERMANDER 3 1' 1' herbt u Useful under same conditions as (Veronica chamaedrys) perennial Drug Speedwell. Acidic-circumneutral soils, full sun or shade. Es- tablish from transplants or sods. Available.

16 Table 2. Plants recommended for limited use on Minnesota roadsides (continued)

Plant Plant Salt Evaluation, comments, and Name zone height Spacing* Type tolerance:t: availability

SPIREA, BILLIARD (figure 51) 4 3' 3' woody u Spreading shrub - spreads slowly (Spiraea billiardi) on fertile sites to form solid mass. Establish from transplants. Avail- able.

SPIREA, DWARF GARLAND 4 1' 1' woody u Suited only to fertile, cultivated (figure 52) sites. Establish from transplants. (Spiraea arguta compacta) Available.

STEPHANANDRA, CUTLEAF 4 3' 2' woody u Low arching plant - tends to tip- (Stephanandra incisa 'Crispa') root in the manner of black raspberries. Establish from transplants. Limited availability.

STEPHANANDRA, DWARF CUTLEAF 4 2' 1' woody u Smaller form than Cutleaf, of more (figure 53) arching habit. Full sun or part (Stephanandra incisa 'Crispa Nana') shade. Available.

STONECROP, TWO-ROW (SEDUM) 4 4' 1' herbt u Has persisted for 5 years on 1-494 (figure 54) site. Adapted to stony banks, par- (Sed111n spurium) ticularly exposed bedrock. Of very limited use. Establish from transplants or sprigged. Available.

SUMAC, ROCKY MOUNTAIN 3 8' 2-3' woody u Similar to but less hardy than com- (R/111s glabra cismontana) mon Smooth Sumac. Establish from transplants. Must be contract grown.

SWEETFERN (figure 55) 2 2-3' 2' woody + A native ground cover of excellent (Comptonia peregrina) qualities. Acid soils and full sun. Establish from transplants. Avail- able.

VETCH, BIRD (figure 56) 3 2' herbt u Hardy perennial vetch similar to (Vicia cracca) vine Hairy Vetch. Suggested for trial because of perennial character. Seed from SCS.

VETCH, HAIRY 3 2' herbt u This species is in common use. (Vicia vi/losa) annual Suitable for use as a soil builder and temporary cover or in grass mixtures. Acidic to circumneutral soils, full sun. Establish from seed. Available.

VIRGINSBOWER (figure 57) 3 2' 1½' vine u Recommended as viny ground cov- (Clematis virginiana) er. A common native that frequently covers railroad banks with a thick growth. Needs more trial as experimental planting on rough banks. Best in full sun, but will tolerate some shade. Will climb to 15 feet. Establish from transplants. Available.

17 Table 2. Plants recommended for limited use on Minnesota roadsides (continued)

Plant Plant Salt Evaluation, comments, and Name zone height Spacing* Type tolerance:t: availability

WOLFBERRY (figure 58) 2 4' 2' woody u Hardy native - may be useful on (Symphoricarpos occidentalis) dry banks. Easily propagated. Broadly adapted to various soil pH's. Full sun. Establish from cuttings and division. Must be contract grown.

WORMWOOD, SILVERMOUND 3 1' 1' herbt u Limited value, suitable only for (Artemisia schmidtiana 'Silvermound') decorative plantings permitting relatively high maintenance. Toler- ates neutral or alkaline soils. Full sun. Establish from transplants. Available.

WORMWOOD, TALL 2 2-3' herbt u A native plant useful only as a (Artemisia caudata) temporary soil cover on light sandy soils. Tolerates a wide range of pH. Requires full sun. Establish from seed. Must be contract grown for seed.

YUCCA, ADAMSNEEDLE (figure 59) 4 4' 2-3' herbt u Does not produce an adequate soil (Yucca filamentosa) cover. Use for decorative effect on dry banks. Establish from plants. Available.

• See footnote references, page 12.

Table 3. Plants not recommended or not sufficiently evaluated for Minnesota roadsides

Plant Plant Evaluation, comments, and Name zone height Type availability

ALFALFA, YELLOW-FLOWERED 3 6" herb* Dense, non-creeping, prostrate PROSTRATE form of potential interest. (Medicago sativa form)

ALFALFA, BLUE 3 2' herb* Not competive under test (Medicago coerulea) conditions.

AMORPHA, LEADPLANT 3 2' woody A native low shrub, does not (Amorpha canescens) produce heavy enough cover to be of use alone. Establishment slow. Requires near neutral or slightly alkaline soils and full sun.

AMORPHA, MOUNTAIN-INDIGO 3 5' woody Similar to Leadplant Amorpha but (Amorpha glabra) insufficiently hardy. Near neutral soils and full sun or part shade. Establish from seed or transplants.

ANTHYLLIS 1 l' herb* No species of anthyllis was Anthyllis cornycina recommended over clovers. All re Anthyllis cytisoides quire near neutral soils and full sun. Anthyllis hamosa Anthyllis lotoides Anthyllis vulneraria

* Herbaceous or nonwoody.

18 Table 3. Plants not recommended or not sufficiently evaluated for Minnesota roadsides (continued)

Plant Plant Evaluation, comments, and Name zone height Type availability

BROOM 5 woody Not hardy in Minnesota. (Cytisus sp.)

BROOM 5 woody Not hardy in Minnesota. (Cytisus sp. 'Choice Mixture')

BROOM 6 1½' woody Not hardy in Minnesota. (Cytisus podolicus)

BROOM, PROSTRATE PURPLE 4 1' woody Recommended only where it can (Cytisus purpurea procumbens) be maintained.

BUGLE, CARPET 5 6" herb* A good creeper but hardiness is in- (Ajuga reptans) sufficient for general use in Min- nesota. Indifferent as to soil and tolerates full sun or shade.

BUGLE, METAI ICA-CRISPA 5 6" herb* A noncreeping ground cover with (Ajuga pyramidalis 'Metalica-crispa') colorful foliage. Not fully hardy in Minnesota.

BUGLE, GENEVA 5 8" herb* A noncreeping ground cover not (Ajuga genevenis) fully hardy in Minnesota. Adapted to a wide range of soils, will grow in full sun or shade.

CANDYTUFT, JORDAN 4 6" semi- Suited for limited use with moder- ( I beris jordani) woody ate maintenance. A low decorative evergreen plant somewhat woody at the base.

CORALBERRY, CHENAULT 5 2' woody Not hardy. (Symphoricarpos X chenaulti)

CORALBERRY, HANCOCK 5 2' woody Not fully hardy, low dense variety. (Symphoricarpos X chenaulti 'Hancock')

CINQUEFOIL 4 1' herb* Failed to grow. (Potentilla megalantha)

CINQUEFOIL, BEAUTY 4 1' herb* Adapted for ornamental use under (Potentilla pulcherrima) cultivated situations.

CINQUEFOIL, BUCCOAN 4 1' herb* Does not produce adequate cover. (Potentilla bucconana)

CINQUEFOIL, BUTTERCUP 4 1' herb* Does not produce adequate cover. (Potentilla ranunculus)

CINQUEFOIL, CI EFT 3 1' herb* Does not produce adequate cover. (Potentilla fissa)

CINQUEFOIL, CUFF 3 3' herb* European species - does not pro- ( Potentilla rupestris) duce adequate cover.

20 Table 3. Plants not recommended or not sufficiently evaluated for Minnesota roadsides (continued)

Plant Plant Evaluation, comments, and Name zone height Type availability

CINQUEFOIL, COLOMBIAN 5 1' herb* Does not produce adequate cover. 1Potentilla andicola)

CINQUEFOIL, CRANTZ 4 4" herb* Does not produce adequate cover. (Potentilla crantzii)

CINQUEFOIL, CREEPING 2 2' herb* Not aggressive enough for ground (Potentilla reptans) cover. May have some value on poor soils.

CINQUEFOIL, RUBY UNDERSNOW 3 1' herb* Does not produce adequate cover. /Potentilla argyrophylla atrosanguinea)

Cl~QUEFOIL, SILVERWEED 3 1' herb* Vigorous spreading perennial - I Potentilla anserina) attractive appearance when green but subject to browning in summer.

CINQUEFOIL, SULFUR 3 3' herb* Weedy species - does not produce IPotentilla rec ta) adequate cover.

CLEMATIS, GOLDEN 5 2' woody Not hardy enough for roadside use. (Clematis tangutica) Climbs to 10 feet.

CLEMATIS, ORIENTAL 5 2' woody Not sufficiently hardy for roadside. !Clematis orientalis) vine Will climb to 15 feet.

CLEM ATIS, SCARLET 3 1' vine An excellent ornamental but not !Clematis texensis) vigorous enough for highway use.

CLEMATIS, SWEETAUTUMN 4 2' vine A strong vine, not hardy enough for (Clematis paniculata) use on exposed roadside banks. Will climb to 20 feet.

CLOVER, BURDOCK 3 1' herb* Not aggressive enough for a ground (Trifolium lappaceum) cover.

CLOVER, EGYPTIAN 3 1' herb* Not aggressive enough for a ground (Trifolium alexandrium) cover.

CLOVER, FOAM 4 1' herb* Not aggressive enough. (Trifolium spumosum)

CLOVER, KURA - 3 1' herb* Not sufficiently competitive. (Trifolium ambiguum)

CLOVER, MOUNTAIN 3 1' herb* Not sufficiently competitive. /Trifolium montanum)

21 Table 3. Plants not recommended or not sufficiently evaluated for Minnesota roadsides (continued)

Plant Plant Evaluation, comments, and Name zone height Type availability

HONEYSUCKLE, TRUMPET 4 2' woody Hardy only in southern Minnesota (Lonicera sempervirens) vine - not vigorous enough for a ground cover.

HONEYSUCKLE, WOODBINE 5 2' woody Not vigorous enough for forming a (Lonicera periclymenum) cover and not hardy. Will climb.

HUCKLEBERRY, BLACK 3 2-3' woody Sandy acid soils. May have a (Gaylussacia baccata) limited application.

IVY, BOSTON 5 1' woody Not hardy enough for roadside use. (Parthenocissus triscuspidata)

IVY, BULGARIAN 5 1' vine Not fully hardy. Useful only as a (Hedera helix 'Bulgaria') evergreen garden ground cover. Acid to circumneutral soils. Full sun or shade. Will climb.

IVY, OGALLALA 5 1' vine Same as Bulgarian. (Hedera helix 'Ogallala') evergreen

JUNIPER, ALPINE 2 6" woody Insufficient evaluation. (Juniperus horizontalis evergreen 'Alpina')

JUNIPER, ANDORRA 5 1' woody Tends to burn in winter. Does not (Juniperus horizontalis evergreen always form adequate ground cover. 'Plumosa')

JUNIPER, BLUISH CREEPING 2 1' woody Color variant of Creeping Juniper. (Juniperus horizontalis evergreen Insufficient evaluation. 'Subglaucus')

JUNIPER, BLUE DANUBE 4 2' woody Insufficient evaluation. (Juniperus sabina evergreen 'Blue Danube')

JUNIPER, BLUE VASE 2 1' woody A nonspreading upright variety. (Juniperus horizontalis evergreen 'Blue Vase')

JUNIPER. BROADMOOR 4 2' woody Insufficient evaluation. Low, (Juniperus sabina 'Broadmoor') evergreen hardier selection similar to Arcadia Juniper.

JUNIPER, COMPACT ANDORRA 2 1' woody Subject to winter burn. Slow- (Juniperus horizontalis evergreen growing and of good form. 'Plumosa Compacta')

JUNIPER, DWARF JAPANESE GARDEN 4 1' woody A fine ornamental but too slow. (Juniperus procumbens evergreen 'Nana')

24 Table 3. Plants not recommended or not sufficiently evaluated for Minnesota roadsides (continued)

Plant Plant Evaluation, comments, and Name zone height Type availability . -----··--·-- JUNIPER, EXIMIUS CREEPING 2 1' woody Insufficient evaluation. (Juniperus horizontalis 'Eximius') evergreen

JUNIPER, IOWA 4 6' woody Upright - good for background (luniperus chinenis evergreen planting. Not a ground cover. 'Iowa')

JUNIPER, MOUNTAIN PROSTRATE 2 1' woody A compact slow-growing form of (Juniperus communis evergreen fine appearance - not vigorous saxatilis) enough for roadside use.

JUNIPER, SAVIN 5 3' woody Hardiness is borderline. (Juniperus sabina) evergreen

JUNIPER, SHORE 6 1' woody Excellent salt resistant ground cov- (J11niperus confer/a) evergreen er. Not hardy in Minnesota.

JUNIPER, SILVERY CREEPING 2 1' woody Insufficient evaluation. (Juniperus horizontalis 'Argenteus') evergreen

JUNIPER, TAMARIX 4 2-3' woody Not fully hardy on exposed sites. (J11niperus sabina evergreen tamariscif olia)

JUNIPER, VON EHREN 4 2' woody Does not form adequate cover. (luniperus sabina evergreen 'Von Ehren')

JACOBS LADDER 3 3' herb* Of value only in native mixtures. (Polemonium reptans)

LESPEDEZA, JAPANESE 4 3-4' woody Ragged, woody bushclover - up- (Lespedeza japonica right habit. Does not develop intermedia) good cover.

LICORICE 4 3' herb* Offers no advantage over native (G iycyrrhiza echinata) licorice (G. lepidota). Needs more hardiness evaluation.

LICORICE 4 3' herb* Offers no advantage over native. (Giycyrrhiza glabra) Needs more hardiness evaluation.

LIPPIA 4 6" herb* Not reliably hardy. Also allows (Lippia cuneifolia) weeds' growth. Circumneutral to alkaline soils.

LOCUST, PROSTRATE BLACK 5 3' woody Not reliably hardy in Minnesota. (Robinia pseudoacacia 'Prostrate') shrub

25 Table 3. Plants not recommended or not sufficiently evaluated for Minnesota roadsides (continued)

Plant Plant Evaluation, comments, and Name zone height Type availability

ST. JOHNSWORT 5 2' herb* Not hardy in Minnesota. (Hypericum polyphyllum)

SANDMYRTLE, ALLEGHENY 4 1' woody Broadleaf evergreen not reliably (Leiophyllum buxifolium subshrub hardy in Minnesota. 'Prostratum')

SARSAPARILLA, BRISTLY 3 2-3' woody A subshrub, woody at the base. For (Aralia hispida) use in mixtures on sterile sandy soils. A native species on such soils.

SCORPIONSENNA 6 10' woody Not hardy in Minnesota. (Coronilla emerus)

SKUNKBUSH, DWARF 3 2' woody Unaggressive. A smaller form of (Rhus trilobata "Dwarf") shrub Skunkbush.

SNOWBERRY, MOUNTAIN 5 2' woody Not as hardy as Snowberry. (Symphoricarpos oreophilus)

SNOWBERRY, WASHINGTON 5 3' woody Not fully hardy. (Symphoricarpos hesperius)

SOAPWEED 4 3' herb* Not a sufficient ground cover. (Yucca glauca)

SPURGE, JAPANESE 5 1' evergreen Suited only to protected fertile sit- (Pachysandra terminalis) herb* uations. Acidic to circumneutral soils, part or full shade.

SUMAC, HYBRID SMOOTH 3 8' woody Similar to, but not superior to (Rhus glabra borealis) shrub Smooth Sumac.

SUNROSE, ARCTIC 3 1' herb* Requires exacting care. Not suited (Helianthemum arcticum) for roadside planting. A garden ground cover. Full sun.

SWEETCLOVER, CRIMEAN 4 2' herb* Low-growing sweetclover - needs (Me/ilotus taurica) further observation.

SWEETCLOVER, YELLOW 3 4' herb* Coarse, rank, irregular weedy (Melilotus officinalis) growth.

TANSYBUSH 6 4' woody Circumneutral to calcareous soils, (Chamaebatiaria millefolium) full sun. Unsatisfactory cover.

TREFOIL, DOUBLE BIRDSFOOT 2 1' herb* Ornamental selection that must be (Lotus corniculatus propagated vegetatively. 'Floro-pleno')

VETCH, COMMON 3 2' herb* Does not produce adequate ground (Vicia sativa) annual cover. Similar to Hairy Vetch.

28 Table 3. Plants not recommended or not sufficiently evaluated for Minnesota roadsides (continued)

Plant Plant Evaluation, comments, and Name zone height Type availability

VETCH, WOOLYPOD 4 2' herb* A vigorous vine similar to Hairy (Vicia dasycarpa) Vetch. More evaluation needed.

VIOLET 2 6" herb* Not aggressive enough for highway 1Viola sp.) ground cover. Native species of circumneutral soils. Full sun or shade.

VIRGINSBOWER; WESTERN 5 2' vine Similar to C. virginiana. Not fully (Clematis ligusticifolia) hardy, no superiority over other clematis species. Circumneutral to slightly acid soils, full sun. Will climb to 15 feet.

WHIN, DWARF 7 1' woody Not hardy in Minnesota. (U/ex nanus)

WILLOW, DWARF PUSSY 2 3' woody A low shrubby native willow oc- /Salix tristis) curring on sandy acidic soils and in full sun. Requires future evaluation.

WINTER CREEPER 5 3' vine Not hardy in Minnesota. /Euonymus fortunei)

WOLFBERRY, CHINESE 4 4' woody Does not compete well with (Lycium chinense) grasses and weeds. Salt tolerant.

WULFENIA 3 1' herb* An uncommon prairie native, ! Wulfenia bullii) suited only in prairie mixtures.

YELLOWROOT 5 4' woody Not fully hardy in Minnesota. Needs ! Xanthorhiza simplicissima) shrub moist soil. Acidic to circumneutral soils.

II. Evaluation of Plant Materials

EVALUATION OF PLANT MATERIALS AND HARDINESS The earlier years of the project were devoted to acquisition pagated for field planting or planted directly into field nur and evaluation of potential ground cover materials. Procure series. Materials were evaluated qualitatively for: winter har ment was accomplished in the following ways: ( 1) from nur diness, propagation requirements, cultural requirements, and senes, arboretums, botanical gardents, USDA Plant Introduc longevity. tion Service, and experiment stations around the world; and Most of the evaluation was associated with field planting .(2) .by individual exploration and collection of native mater and observation of performance over the seasons for several ials Ill natural habitat areas. There were over 500 accessions years. Ability to survive Minnesota winters was the basis for from 318 different species processed through the program; judging winter hardiness in this project. !27 of the plant materials evaluated in this project were col lected directly from the wild. Cultural evaluation considered the following: minimum . The procedure for evaluation included cataloging and veri maintenance requirements, fertility needs, need for supple fymg each acquisition for positive identification. Following mental watering and soil preference. Evaluations also included identification, materials were processed and if necessary pro- rate of growth, form, foliage characteristics, flowering and

29 Crownvetch and Empire Birdsfoot Trefoil was applied to a Table 7. 1969 evaluation-Loon Lake plantings (plant small area near the transplants. The transplants responded well ed 1964 and 1965) and grew rapidly. Germination of the seeded area was satis factory and an abundance of seedlings of both species was present by midsummer. Growth of Birdsfoot Trefoil was rapid Plants Performance-1969 but that of Crownvetch relatively slow. The response of both species, however, was considered so Tall Wormwood Fair. Suitable as temporary cover promising that plans were made for a more extensive planting on light sandy soils. the following year. To facilitate planting, arrangements were made to have the site graded to eliminate the gulleys. Grading Dwarf Southernwood Failure. Not adapted to soils of largely destroyed the 1964 planting, but evidence of the per site. sistence of established Crownvetch was demonstrated by the sprouting of many crowns and rhizomes from the old planting Japanese Trailing Poor. Survived but lacks vigor un during the 1965 growing season. Raspberry der these soil conditions. The planting was made May 21, 1965 with seeds and transplants in alternating vertical rows along the south-facing slope. Plants and seeds were grouped into three lots. Each lot Bristly Sarsaparilla Adapted to light sands but has not of seeds and plants was planted in alternating rows of grass transplanted easily. Performance seed, 4 feet wide, and forbs 3 feet wide with the arrangement poor to fair. randomized for each class of material in the three replications. A second planting, of seeds only, was made adjoining the first. Lowbush Blueberry Failure. Gravel soil not suited for This consisted of vertical strips 4 feet wide, each strip repli the acid soil plant. cated three times. Plants were set by trowel and seedings raked lightly to cover the seed. Fertilizer, 10-10-10, was applied to Arnold Dwarf Forsythia Failure. Not adapted to soils of the site at a rate of about 400 pounds per acre at seeding time area and not sufficiently winter and again in 1966 and 1967. hardy for this location. A small trial planting of Dwarf Southern Wormwood, Arnold Dwarf Forsythia, Dwarf Bushhoneysuckle, Japanese Trailing Raspberry, and "Winona" Crownvetch was made for Dwarf Bushhoneysuckle Failure. Not adapted to soil con observation purposes on the south side of the road. Most of the ditions. balance of this highly erodible slope was sown to a mixture of Empire Birdsfoot Trefoil, Penngift Crownvetch, Timothy, Sweetfern Fair. Survival poor because of con Sideoats Grama, Flat Peavine, Sand Dropseed, and Switch dition of planting stock. grass to prevent a recurrence of severe erosion. The planting was first evaluated July 1, 1965 for germina Smooth Sumac Fair. Slow to take hold on this site. tion of seed and survival of the transplanted materials. Heav iset germination noted was in Empire Birdsfoot Trefoil. Good germination was noted in Tall Wormwood and Penngift Crown Hughes Creeping Juniper Good. vetch. The poorest but still fairly satisfactory germination occurred in Chemung and "Winona" strains of Crownvetch. Reynoutria Fleeceflower Poor. Not adapted to the soil. Flat Peavine failed to germinate satisfactorily. Final evaluation was made in 1969 ( table 7). Blue Creeping Juniper Very good. Well adapted to poor The poor performance of the following five species of sandy soil. plants indigenous to the immediate area: Sweetfern, Dwarf Bushhoneysuckle, Lowbush Blueberry, Smooth Sumac, and Pirone Alfalfa Poor. Died out. Bristly Sarsaparilla requires some interpretation since this re port emphasizes encouragment of the wider use of native plant species in the long range development for highway roadsides. Sicklepod Alfalfa Excellent, vigorous. Needs closer The glacial till is of a very different structure and higher pH planting to provide full cover, but than that of the undisturbed surface soils of the area. All but worth further investigation. sumac are plants adapted to acid soils. As weathering proceeds and a soil of more normal character for the area develops on Crownvetch All varieties good but germinati~n this site, these species may find conditions more suitable. and establishment were best m Penngift followed by Emerald. Che mung and "Winona" were about Wendigo Slope, Community Park Plantings-1965 equally behind the first two var ieties. Subsequent development has The planting site was located 7 miles southeast of Grand largely eliminated any differences Rapids on County Highway 67, on a stony, rough slope with between the varieties in soil cover out topsoil. It was a typical problem bank composed of ing capability. coarse-textured glacial till. Both east and west facing slopes were used. On May 21, 1965 plantings 10 feet wide and varying in Birdsfoot Trefoil, Empire The most vigorous and most rapi~ lengt~ from 20 to 40 feet depending on position, were made ly establishing species tried on this runnmg the length of the slope. The seed was simply scattered site. It has spread freely over the and the gravel lightly raked to provide some seed cover. Plots whole planting area. were sown with Empire Birdsfoot Trefoil, Penngift Crown vetch, Flat Peavine, and Sand Dropseed in three replications. Additional Empire Birdsfoot Trefoil was sown on other parts season. Crownvetch and Flat Peavine were comparatively slo~ of the slope. A slope of lower profile across the road was also in germinating and no significant cover developed in 19_6 planted with Penngift Crownvetch, Empire Birdsfoot Trefoil from these species. In 1966 Birdsfoot Trefoil continued Jo give and Flat Peavine. ' excellent and impressive ground cover. Birdsfoot Tref01l gr_ew Germination, establishment, and growth of Birdsfoot Tre freely over the slopes and into the rills and gulleys producmg foil was rapid. A good cover resulted during the first growing a heavy mat of protective vegetation. Crownvetch and Flat

32 Pcavine were apparent in 1966, but very few plants of the Table 8. Iron chlorosis on potential ground cover plants latter species grew. grown at Crookston, Minnesota, 1967* In 1967 Birdsfoot Trefoil still was the dominant ground cover. Penngift Crownvetch was beginning to cover the areas where it was planted. Flat Peavine was still present but not in No chlorosis Mild chlorosis Severe chlorosis sufficient quantity to be an effective ground cover. On the basis of this trial, Empire Birdsfoot Trefoil is Quicksilver Petunia Empire Birdsfoot Dwarf Bush recommended for initial cover on bare slopes in this northern Trefoil honeysuckle Minnesota area. Goatsrue Elliott Birdsfoot Bronx Forsythia Trefoil Penngift Crownvetch MORRIS STATION-1967 Cicer Milkvetch Smooth Sumac This was a two-part planting on a roadside near the Ex Pirone Alfalfa Dwarf Southern periment Station. The first area included transplants while the wood second area consisted of replicated sowings of Penngift Germander Crownvetch, Empire Birdsfoot Trefoil, Cicer Milkvetch, and Speedwell Flat Peavine. Emerald Crownvetch There has been an appreciable improvement in the quality Winona Crownvetch of the Morris planting since it was fertilized heavily in 1967 and 1968 with complete 10-10-10 fertilizer at about 400 • Kalms St. Johnswort failed to establish from seed. Plants of Fringed pounds per acre. Response has been especially good in Crown Sage were dead by fall 1967. wtch and Empire Birdsfoot Trefoil. Pirone Alfalfa and Car sticn Alfalfa have completely disappeared. The performance of Dwarf Southernwood has not been impressive and plants Initial plantings of Pirone Alfalfa at the Landscape Ar have spread very little. boretum and Horticultural Research Center created consider Satisfactory material on this site include the following: able interest because of dense, low vigorous growth and over all attractive appearance. The only success in other locations Empire Birdsfoot Trefoil (seeding) has been at the Crookston Station where it continues to rank Penngift Crownvetch (seeding) among the best of the ground cover species. As with Cicer Cicer Milkvetch (seeding) Milkvetch, there seems to be a marked ability to thrive on Flat Peavine (seeding) gumbo type alkaline soils. This species of alfalfa is not cur Crown vetch (crowns) rently available commercially; Seed for experimental plantings was obtained from the USDA Plant Introduction Station, Unsatisfactory materials include the following: Ames, Iowa. Further use or investigation of Pirone Alfalfa Pirone Alfalfa would require seed production from foundation material. Carstien Alfalfa All Crownvetch varieties displayed some symptoms of chlorosis during the second growing season. The chlorosis Reynoutria Fleeceflower however has not limited the quality of ground cover produced. Dwarf Southernwood The yellowish foliage is unattractive. _Dwarf Southernwood performed poorly on this site. It was Germander Speedwell, a low plant of the Mint Family, a. disappointment since it is tolerant of soils with a relatively which spreads by rhizomes under favorable soil and moisture, high pH. The low fertility and dry soil of this roadside cut grew well only the first year. undoubtedly contributed to its failure. This is the only planting in which the Birdsfoot Trefoils have not been rated with the best ground covers. Empire and "Elliott" strains displayed mild chlorosis on this site. Univer CROOKSTON STATION-1965 sity of Minnesota legume specialists suggest that Birdsfoot Plant evaluation experiments were established in June Trefoil should grow well in open situations in the Red River 1965 on the Northwest Experiment Station at the University Valley. Initially, Birdsfoot Trefoil may best be limited to trial of Minnesota Technical College, Crookston, Minnesota. The plantings. plantings were established to determine winter hardiness and tolerance to the high pH soils (7.5-8.1) of the Red River Val ley area. There has been no change in the relative ratings of HIGHWAY SITE EVALUATIONS the species since 1967. 1-494 HIGHWAY PLANTING-1963 Iron chlorosis, causing subsequent decline and ultimate death, is a serious physiological problem with many plant ma In cooperation with personnel of the Minnesota Depart terial~ grown in the high lime soils of the Red River Valley. ment of Highways, a site for planting ground covers was Iron 1s ~ot available in sufficient quantity for plant growth selected on Ossanna Hill, Station 189, 1-494 in Eden Prairie under high lime conditions. Iron chlorosis has been observed Township (figure 60). on many of the species planted at Crookston ( table 8). The planting site was used for a greater variety of plant . C1cer Milkvetch, Goatsrue, and Pirone Alfalfa, which materials than any of the others used in this research project. thnve u~der the soil conditions of the Crookston area, per The quality of the site was not an ideal one for the growth of formed impressively. Crownvetch has grown quite well there, plants but is characteristic of roadside conditions. The en hut does. suffer from mild chlorosis, making it less attractive vironmental conditions for plant growth are minimal in terms an_d po~s1bly shorter-lived than when grown on more suitable of soil fertility and moisture. The west exposure of the slope soils. C1cer Milkvetch performed well and is recommended for further aggravates the harsh conditions present. trial plantings on roadsides as a substitute for Crownvetch in Excessively rainy weather delayed planting until June 21, a_lkaline soil areas. Goatsrue has a more upright and less de 1963. Seedings were sown by hand in furrows, transplants sirable open growth habit than Cicer Milkvetch. A satisfactory were planted directly with a minimum of soil preparation. All cover f_ro~ Goatsrue may be obtained from heavy seedings. plantings were replicated four times in plots 10 feet by 10 . Qmcks1lver Petunia developed a spreading mat that was feet. rtrernely effective in excluding annual weeds; it reseeded Transplanted materials were successful except for Reynou i recly and performed exceedingly well. Its annual nature Jim tria Fleeceflower, which might have been too young and the ts Its usefulness to small scale planting or temporary cover. division pieces too small to establish satisfactorily.

33 Performance Final Performance Final Class of 1 year after rating Reason if Class of 1 year after rating Reason if Plant material planting 1969* unsatisfactory Plant material planting 1969* unsatisfactory

Arnold Dwarf plants 2 3 not fully Cutleaf Blackberry plants 2 not hardy Forsythia hardy or aggressive Drophip Rose plants 3 died out Rosendahl plants 3 3 poor cover Western Red plants died out Dewberry Raspberry Carstien Alfalfa plants 3 3 unsatisfactory growth Snowberry plants poor stock

Sicklepod Alfalfa plants 2 3 died out Meadow Rose plants poor establishment Goatsrue plants 2 3 poor cover Max Graf Rose plants poor establishment Japanese Trailing plants 2 3 not Raspberry vigorous Pirone Alfalfa plants died out Fringed Sage plants 2 3 not vigorous Georgia Bushhoney- plants poor estab- suckle lishment Billiard Spirea plants 2 3 not vigorous Dwarf Bushhoney- plants poor estab- suckle lishment Bayberry plants 3 3 died out Buckbrush plants poor estab- (Wolfberry) lishment Gold Drop Shrubby plants 4 poor Cinquefoil survival Creeping Mahonia plants 2 died out

Memorial Rose plants 2 not hardy Olympic St. plants 2 died out Johnswort Silver Fleeceflower plants 2 not hardy Sweetfern plants failed to grow Bronx Forsythia plants 2 not hardy Chinese Wolfberry plants 3 poor cover Sicklepod Milkvetch seed 3 poor cover produced

Leadplant Amorpha seed did not es- Southern Bush- plants poor estab- tablish well honeysuckle lishment

Flat Peavine seed did not es- Prostrate Black plants 3 died out tablish well Locust

Thicket Creeper plants did not es- Wolfberry cuttings no eval- failed to tablish well uation root

Aaronsbeard St. plants 2 not hardy Georgia Bush- cuttings no eval- failed to Johnswort honeysuckle uation root

Chinese Wolfberry plants 3 poor Sweetfern root no eval- failed to growth cuttings uation root

Canada Milkvetch seed 3 poor estab- Southern Bush- cuttings no eval- failed to lishment honeysuckle uation root

Purple Four-leaf plants 1 poor Dwarf Bush- cuttings no eval- failed to Clover survival honeysuckle uation root

35 root cuttings in the nursery, but young plants require careful Performance Final watering and cultural treatment difficult to provide under Class of 1 year after rating Reason if open field conditions. Plant material planting 1969* unsatisfactory Satisfactory plants on the Soderville, TH-65 site include two native selections of Cree.ping Juniper, Skandia Juniper, Chemung Crownvetch, Penng1ft Crownvetch, and Bayberry. Goldflame Honey- cuttings no eval- failed to Andorra Juniper, Tamarix Juniper, and Japanese Trailing suckle uation root Raspberry performed well but did not develop ground cover comparable to the preceding more highly rated species. The following plants failed or were unsatisfactory in quality of Lilac Honeysuckle cuttings no eval- failed to cover produced: Sweetfern, Lowbush Blueberry, Huckleberry, uation root Dwarf Southernwood, Yucca, Cowberry, Olympic St. Johns wort, Alaska Phlox, Bristly Sarsaparilla, Fringed Sage, Wine Dwarf Bush- cuttings no eval- failed to leaf Cinquefoil, Silverweed, and Bearberry. honeysuckle uation root Wild Strawberry (Fragaria virginiana) although not planted on this site, has occupied a substantial area in the plantings. This native species is well adapted to sandy soils and bears Sweetfern root no eval- failed to some consideration as a ground cover where native plants are cuttings uation root to be encouraged. The cover produced is not dense but may be adequate to protect the soil. Arctic Pfitzer plants no eval- died first Juniper uation season

Broadmoor Savin plants no eval- died first CLEVELAND AVENUE, ROSEVILLE, RAMSEY COUNTY Juniper uation season DWARF SOUTHERNWOOD PLANTINGS In April 1965, a large planting of Dwarf Southernwood, San Jose Creeping plants no eval died first also known as Dwarf Sage or Dwarf Wormwood, was made Juniper uation season on a steep west-facing bank on the interchange of I-35W and TH-36. Five thousand plants were planted in a staggered ar rangement at 18 inch intervals on the site which measured Blue Rug Creeping plants no eval- died first 400 feet by 30 feet. At the time the slope carried a light cover Juniper uation season of Smooth Bromegrass and some Kentucky Bluegrass. Early work with Dwarf Southernwood had indicated con siderable promise for its wider use and extensive trial as a highway ground cover. This plant grew rapidly and was read ily increased by cuttings at almost any time of the year in the greenhouse. The plant has a pleasing gray-green color and the TH-65 PLANTINGS-SODERVILLE, ANOKA COUNTY leaves persist into the winter months, presenting the effect of This site was selected for evaluation of plant materials on a nearly evergreen low shrub. sandy soils. The site, a 3: 1 cut located on the west side of TH During summer 1965, plants were hoed periodically to re 65, was characteristic of the infertile soils of the Anoka sand duce weed competition. Fertilizer was applied at the time of plain. Ten foot by ten foot plantings made on May 13, 1964 planting and in 1967 and again in 1968. and April 23, 1965 were laid out in two tiers on the slope. Competition became severe enough to jeopardize the Plantings were watered at weekly intervals using a sprayer planting in 1967. In late May and again on July 24 the grasses rig. To provide better watering facilities for newly transplant were sprayed with an herbicide as a control measure. This ed materials, a sand point to which a portable shallow well freed the Dwarf Southernwood plants temporarily from com pump could be attached was driven into the water table in petition. Herbicide control was repeated in 1968. May 1965. With this arrangement, more thorough and more The overall performance of this planting is not satisfac frequent watering was possible. tory. It is irregular in appearance, partly from weed compe All juniper varieties, Chemung Crownvetch and Bayberry tition but more from washing out and remedial sodding that performed well on this site ( table 10). Two raspberries, Ros was done during the first month after the planting was estab endahl and Japanese Trailing, survived moderately well but lished. On the basis of the performance on this and other sites have not produced an effectively dense cover. Blueberry, the previous recommendation of this species for large scale S:,veetfern, Bristly Sarsaparilla, and Huckleberry did not sur trial has been revised. Dwarf Southernwood is recommended vive on the upper slope; however, adequate establishment was for limited use on suitable soils where it can be maintained realized on the lower slope. Cowberry and Bearberry survived under cultivation until well established. only on the more moist lower slope. Yucca did not produce adequate cover. The relatively good performance of Crownvetch and Bay LAKEVILLE, 1-35 PLANTINGS-1967 berry on this site was not anticipated. Apparently once deep roots were established, these species were able to obtain ade Juniper Planting qu~te water despite dry surface conditions. Pocket gophers, In spring 1967 a site was selected for experimental plant eatmg the rather fleshy roots of the shrub, severely damaged ings on a newly completed section of 1-35 in Lakeville To~n the bayberry planting. ship, Dakota County near County Highway 70. An east f:icing The difference in performance between the closely related exposure on fill approaching a bridge was selected. Jumpers, Sweetfern_ and Bayberry undoubtedly reflects the quality of deciduous shrubs, and perennial materials were planted for the plantmg _sto~k rather than the inherent potential for evaluation as ground covers and of establishment procedures. g'.o.~th on this site. Bayberry planted from root pieces and The juniper plants used in this study were balled and bur d1v1s10ns from old plants performed just as poorly as similar lapped stock grown in the Arboretum nurseries ( table 11) · stock of Sweetfern. Well rooted nursery grown seedlings of Plantings were made on May 12 and 15, 1967. Plants were Bayberry, however, adapted readily and grew well. Both spaced 3 feet apart in staggered rows and mulched with wood Sweetfern and Bayberry are readily increased by division or chips to inhibit weed growth and conserve soil moisture.

36 Table 10. 1969 evaluation of materials planted in 1963 and 1964 on TH-65

Class of Initial Final Reason if Plant material performance rating* unsatisfactory

Creeping Juniper 2 year plants 1 1

Skandia Juniper 2 year plants 1 1

Chemung Crownvetch 2 year plants 1 1

Creeping Juniper 2 year plants 1 1

Japanese Trailing 1 year plants 3 2 thin cover produced on Raspberry this site

Andorra Juniper 2 year plants 2 2 hardiness not as satisfactory as in other creeping junipers

Yucca 1 year plants 2 2 cover too incomplete - decorative function only

Tamarix Juniper plants 2 2 good growth - hardiness somewhat questionable

Sweetfern ( spring dug) wild stock 3 3 proved difficult to establish from wild dug plants

Blueberry 3 year seedlings 3 3 most died out on dry upper slopes

Fringed Sagebrush plants died out

Blueberry 2 year seedlings 3 poor establishment

Sweetfern (fall dug) wild stock 3 poor establishment

Oldfield Juniper 2 year plants failed to become established - poor planting stock

Wineleaf Cinquefoil plants failed to establish

Sweetfern wild stock failed to establish

Bristly Sarsaparilla wild stock failed to establish

Sweetfern root cuttings failed to grow

Huckleberry 2 year seedlings failed to establish

Olympic St. Johnswort 1 year plants not hardy

Dwarf Southernwood 1 year plants 3 not adapted to sand soil

• 1 = Excellent, 2 = Good, 3 = Poor.

37 Table 11. Performance of selected junipers after 2 straw to conserve soil moisture and provide erosion protection years on the Lakeville site: planted 1967 to the slope ( table 12). In table 12, only the Birdsfoot Trefoil varieties have estab lished a satisfactory cover. 1969 Percent Deciduous Shrub Planting ground 1969 In autumn 1967 a planting of dormant deciduous shrubs Plant cover Rating* was made to observe performance under highway slope con ditions. Single row vertical plantings of 12 plants each were Creeping Juniper 30 2 made in four replications with plants spaced 3 feet apart in Creeping Juniper 20 2 the row. Survival of the plants has been complete ( table 13). Creeping Juniper 20 2 Creeping Juniper 60 1 Marshall Creeping Juniper 50 1 Table 13. Performance of deciduous shrub plantings: 3 Andorra Juniper 40 planted 1967 at Lakeville Japanese Garden Juniper 80 1 Pfitzer Juniper 60 2 Blue Pfitzer Juniper 60 2 1969 Savin Juniper 55 2 Plant Rating•:• Tamarix Juniper 60 2 Skandia Juniper 75 1 Dahurian Rose 2 Kamchatka Rose 1 • 1 = Excellent, 2 = Good, 3 = Po•,r. Rose (unidentified) 3 Georgia Bushhoneysuckle 2 Cutleaf Stephanandra 2 Marshall Creeping Juniper is a vigorous bluish-green variety that produced a dense mat of vegetation. It is the best • 1 = Excellent, 2 = Good, 3 = Poor. material in this planting and has performed well elsewhere. Japanese Garden Juniper also performed well but did not grow as rapidly as the Marshall Creeping Juniper. It produced The most effective plant in this group is the Kamchatka a dense blue-green foliage that covered the soil well. Rose. This is an extremely hardy (zone 2) rose from north The Skandia Juniper is a hardy form of Savin Juniper of eastern Asia. The plants spread freely by suckering and reach low arching habit but does not have the free running habit of a height of about 4 feet. The shrub flowered profusely. Creeping Juniper. This juniper was fully hardy exhibiting no The Dahurian Rose is similar in habit to the Kamchatka winter injury. Rose but did not perform quite as well. Both Pfitzer and Blue Pfitzer Junipers are satisfactory The unidentified rose species was grown from seed col plants for southern Minnesota in areas where exposure is not lected near Central City, Colorado. In the native location it extreme. Plants grow into an arching shrub. Planted closely produced an open thicket of stems about 3½ feet high. Its (3 to 4 feet) they produce a heavy cover. Minnesota growth was unsatisfactory and compared unfavor- Andorra Juniper is a juvenile form of Creeping Juniper ably with the above two species. . with little tendency to spread. The juvenile foliage is more Georgia Bushhoneysuckle is larger and grows m~re vigor tender than that of varieties that develop mature foliage. ously than the native Dwarf Bushhoneysuckle but 1s ~ot as The variety showed little tendency to creep in this plant hardy. There was evidence of winter injury on the f!latenal on ing and exhibited winter injury. Savin Juniper and the Tama this site although the species has performed well m the Ar- rix variety of the same species were more prone to winter boretum for 10 years. . injury than the other species discussed above. Cutleaf Stephanandra is a low scr~mbling plan~ with branches that tend to strike toot when m contact with the Legume Seedings soil. This material exhibited injury on exposed branch tips. Cicer Milkvetch, Sicklepod Milkvetch, Flat Peavine, On an exposed site it is possible more severe injury may occa Schimid Lespedeza, Birdsfoot Trefoil, and Bird Vetch were sionally be experienced, otherwise it would make an excellent planted May 12, 1967. Plantings were made in vertical strips ground cover. in two tiers with three replications. The slope was prepared by raking. Inoculated seed was hand sown and the soil lightly NATIVE GROUND COVER COLLECTIONS raked to cover the seed. The seeded area was mulched with There are two native Minnesota junipers suitable for ground cover use: Prostrate or Oldfield Juniper and Creepmg Table 12. Germination and ground cover evaluation of Juniper. The native species of yew, Canada Yew (Taxus cana herbaceous materials: planted 1967 at Lakeville densis), has a suitable shrubby habit but limited side adapta bility and is quite unsuited to general roadside situations. Both Prostrate and Creeping J unipcr are widely distri~uted 1967 1969 in northern North America. Both species have given nse _to Percent Percent many improved cultivated varieties. In Minnesota both spe~i~s Plants germination ground cover have statewide distribution except for the southwest pra_me area. On the premise that native plant materials are a logical Birdsfoot Trefoil (Fridley) 70 85 source for fully adapted varieties, collections of plants. of bot~ Birdsfoot Trefoil, Leo 85 85 species in wild populations in the state were made m 19 6 Birdsfoot Trefoil (SCS) 70 85 and 1963. Schimid Lespedeza 85 45 Plant to plant differences are obvious when closely ob· Cicer Milkvetch 70 15 served in the wild. Experience has demonstrated that these Bird Vetch less than 10 0 differences in habit, appearance, and structural. detail can be Flat Peavine less than 10 0 satisfactorily perpetuated by rooting cuttings. D1fferen~es due to habitat or accident of situation are not under genetic con·

38 trol and therefore are not reproducible in this manner. The been grown under nursery conditions for comparison with seed reproduction of variants such as these is not acceptable commercially available varieties and specimens grown in the because they do not reproduce true to type. Minnesota Landscape Arboretum. Extensive populations of native Creeping Juniper in Otter Up to this time no Creeping Juniper selections have ex Tail and Polk counties were surveyed in October 1963. Col ceeded the more vigorous cultivated clones such as Hughes or lections were made by gathering cutting material from indi Marshall (table 14). Selection 63857, a male clone from Polk vidual plants. Collection was determined on the basis of above County has produced a good quality cover in the nursery: average vigor, attractive appearance, or ground covering ca dense and weed free. Clone 63864 placed in a planting on pacity. Six collections were made in the vicinity of Paul Lake, sandy soil on the TH-65 planting site in Soderville, Anoka Otter Tail County and 11 in southern Polk County on the County has produced a satisfactory erosion protective cover. dunes along the shoreline of glacial Lake Agassiz. Approxi The plants are not obvious due to the presence of annual mately 50 cuttings were obtained from each selected plant. plants and weeds that grow through the rather open cover Cuttings were rooted in the greenhouse and transplanted to provided by the Juniper. In time as the plants thicken, it is one of the project nurseries for observation and comparison. anticipated that weed frequency will diminish and the Juniper The Prostrate or Oldfield Juniper of North America is cover will become more apparent. Other clones in the considered to be a botanical variety of the Common Juniper planting on l-35W in Lakeville, Dakota County have not been of Eurasian distribution. Throughout its distribution range, established long enough for evaluation. All clones of these the plant varies immensely in form from a prostrate shrub to selections require continued observation for some years be an upright tree. Most North American forms are shrubby but fore their ultimate value can be determined. It is not possible differ strikingly on both a regional and individual basis. In to recommend any one of them now as being sufficiently su Minnesota the plant is commonly a low shrub ranging up to perior to substitute for available recommended varieties of 4 feet in height but individuals of low compact habit are the Creeping Juniper. frequently observed. Two such plants were collected in the The two local selections of Prostrate Juniper from East East Bethel, Anoka County area. Bethel, Anoka County, 62880 and 62881, have shown desir Additional sources of variation in Prostrate Juniper were able qualities of vigor and habit of growth. Selection 62880 is obtained from selections made in Massachusetts and of the somewhat lower and of better ground hugging character than Rocky Mountain form from near Central City, Colorado and 62881. Both are vigorous enough to be recommended for the Black Hills of South Dakota. All accessions were propa planting where a heavy juniper cover is desired. Planted at 3 gated from cuttings grown in the Project 615 nursery for foot spacings they developed a solid cover in 2-3 years. observation. No special advantage has been noted in Prostrate Juniper Numerous cultivated forms of both Creeping and Pros selection 65607 from Massachusetts. The Rocky Mountain trate Juniper are available in the nursery trade. Many of them forms under trial grew too slowly to be of value to this pro were introduced into cultivation because of superior qualities gram but are exceedingly fine compact ornamental shrubs. of growth or habit as well as for sheer novelty of appearance. In neither of the above species is there a great tolerance for Obviously any new variety to be introduced must possess some salt and in employing these plants, efforts must be made to quality not already marketed. Collections in this project have place them so as to minimize chemical injury.

Table 14. Rating of Creeping Juniper collected from native stands after 2 years of growth: planted 1963

Number Diameter Performance Source plants Density* (centimeters) 1969

Native Ottertail County 56 4 40 Unsatisfactory Native Ottertail County 14 4 25 Unsatisfactory Native Ottertail County 28 4 27 Unsatisfactory Native Ottertail County 22 4 25 Unsatisfactory Native Ottertail County 21 4 25 Unsatisfactory Native Polk County 22 3 45 Borderline Native Polk County 7 3 40 Acceptable Native Polk County 11 1 50 Acceptable Native Polk County 4 2 45 Acceptable Native Polk County 2 1 50 Acceptable Native Polk County 19 2 40 Acceptable Native Polk County 3 3 40 Borderline Native Polk County 3 4 20 Unsatisfactory Native Polk County 7 3 40 Acceptable

• Density: 1 = Complete weed free cover; 2 = Sufficient cover and soil stabilization, some weed competition; 3 = Borderline. Growth insufficient, weed competition; 4 = Unacceptable cover.

39 In 1963 a selection was made from an unusual Redosier mung, Penngift and "Winona" was made at the Landscape Dogwood shrub growing in the University of Minnesota Ce Arboretum in April 1964. Seedlings were planted at 2 foot dar Creek Natural History Area in Anoka and Isanti counties. by 2 foot spacing in 10 foot by 10 foot blocks replicated This shrub's branches were extremely fine and dense, quite three times. unlike the coarsely textured open character of normal Redosier Observation the first season confirmed the slow initial es Dogwood plants. It apparently matures at about half the height tablishment and growth of Crownvetch. Survival, however of the normal plant. The plant lends itself well to low shrub was complete. During summer 1965 the plants were accident'. plantings and may be particularly useful in areas with wet ally mowed, which delayed evaluation until September 1966. soils. The clone has been named 'Isanti' and is in the process Plants were scored for percentage of soil cover, average height of introduction to the horticultural trade. of plants, relative vigor, and weed frequency (table 15). Barrenstrawberry is a strawberry-like ground cover plant In order of quality of cover, Chemung and "Winona" occurring sporadically in the northeastern United States and varieties formed the best cover followed closely by Penngift. southern Canada. In Minnesota it occurs in Jack Pine areas of Emerald did not develop adequate cover. Chemung and "Win central St. Louis County. It is highly regarded as a ground ona" were the tallest growing of the varieties. Penngift was cover because of its rapidly spreading manner of growth and consistently lower in height and finer textured than the other its showy yellow flowers. Crownvetch varieties. Material was collected near Biwabik, Minnesota and has Plantings with the most vigorous varieties had the fewest been increased extensively in the Landscape Arboretum. It is weeds. The very vigorous Chemung was especially competi included in the ground cover demonstration area. The plant tive, maintaining a weed-clean planting area. The variety Em has not exhibited as much drought tolerance as anticipated but erald was the least competitive resulting in weedy plantings. is of vigorous growth and is worthy of further evaluation as a slope planting material. Dwarf Pussy Willow is a low shrub willow of the prairie oak savanna areas of Minnesota. Its low shrubby habit sug gested its use as a low native ground cover. The plant matures at 2-3 feet. It is readily propagated by cuttings. Table 15. Mean ratings for establishment of transplant This low willow has grown well in preliminary trials but ed seedlings of four Crownvetch varieties; planted May has not been outplanted in suitable test areas. It needs further 25, 1967, and rated July 23, 1968 evaluation. Percent Height Variety cover (centimeters) Weedinesst Vigor:j: EXPERIMENTS IN PROPAGATION AND ESTABLISHMENT Emerald 43 45 3* 1* Crown vetch "Winona" 58* 58 3 2 Crownvetch apparently was first planted in Minnesota Chemung 55 48 2* 2 during the late 1920's or early 1930's. The oldest known es Penngift 43 27 3 2 tablished planting is still growing south of Winona on County 1 Highway 74. This pfanting probably originated from seed sup X 49 X 44 X 3 X plied by the Soil Conservation Service ( SCS). Other SCS orig s 7 s 12 s .4 s .17 in plantings were observed in Redwood County and in a U.S. Forest Service planting in Cass County. This was the most • Indicates extremes beyond 1 standard deviation. northerly location encountered during the early years of Proj t Weediness rated 1 to 4, 1 = fewest weeds. ect 615. During the last 5 years Crown vetch has become es :j: Vigor rates 1 to 3, 1 = least vigorous. tablished throughout Minnesota. Crownvetch has been widely promoted as an all-purpose "miracle" ground cover. Excellent and effective as it is when grown under proper conditions, the plant has a well grounded reputation for being difficult and slow to establish. From seed Visually Chemung and "Winona" are very similar and _it ing time to full cover may require three or more growing is possible that the Chemung variety and the "Winona" strain seasons. arose from the same SCS stock. The long establishment time makes it necessary to plant a A similar but more extensive planting was established nurse crop for initial soil stabilization. Planting crowns (trans from transplanted seedlings in 1967 along the north and south planted pieces of plants or seedlings) may speed the process sides of a new road in the Landscape Arboretum. Perform of developing a full cover under good cultural conditions. ance of the variety Emerald was more satisfactory in this To ensure proper plant growth, the root system of Crown planting. In addition to Chemung, Penngift, and "Winona" vetch must be inoculated with a specific rhizobial bacteria the trial included the Iowa strain known as "Calmar" and a culture which is available commercially. New seedings of USDA Plant Introduction Station selection from Kentucky. Crownvetch should be given 6-12-12 fertilizer at a rate of Variety plantings were replicated three times on each slope. about 500 pounds per acre. Once established, Crownvetch Plots were 10 feet by 10 feet with plant spacing at 2 feet _by ra~e)y requires supplemental fertilization. A pH of 5.5 is the 2 feet staggered intervals. The cover produced in this planting mm1mum tolerated by Crownvetch while a range of 6.0 to 7.5 was complete by July 1968 because of very favorable growmg is optimal. When necessary, lime should be added to correct conditions. There were very few weeds because of the com the pH. plete cover. . ,, _Three methods of establishment were investigated in ex The varieties Emerald, Chemung, Penngift, and "Winona penn:ients under Minnesota conditions: ( 1 ) seeding directly in were sown in replicated rod rows in a Landscape Arboretu~ the f(eld, ( 2) plantiJ?g. ~reenhouse grown seedlings, and ( 3) nursery on June 1, 1964. Germination was somewhat erratic planting crowns or d1v1s10ns. in the absence of irrigation, but a satisfactory stand was 0~ Twenty-seven accessions were grown including the com tained with all varieties except Penngift. The autumn germi mercial varieties: Penngift, Chemung, Emerald, and "Cal nation noted in Penngift and Chemung was evidently ?~e to mar." Seed collected from the Winona stand was also included hard seeds finally responding to increased moisture. Ind1v1dual under the unofficial de5ignation "Winona." plants were measured for height and width at the end of the An experiment using potted seedlings of Emerald, Che- growing season ( table 16).

40 Table 16. Mean heights and widths of four varieties of plantings gave results similar to those reported in table 17 for Crownvetch after one growing season from seed: plant transplanted seedlings. In the nursery trials, however, it was ed June 1, 1964, scored October 7, 1964 possible to observe the spreading capability of individual plants, which is a property of more significance in ground covers than is height ( table 18). The entire planting was in Seedlings such excellent condition that no judgment of variation in vigor Mean Mean was practical (fig. 61). Varieties height width (centimeters) (centimeters) Table 18. Mean heights and widths of five Crownvetch varieties grown from seedings: planted May 9, 1967, Chemung 6.3* 32.5 scored July 23, 1968 Emerald 10.3 35.7* "Winona" 8.7 30.9 Seedlings Penngift 9.4 31.1 Height Width X = 8.7 X= 32.6 Varieties (centimeters) (centimeters) s 1.7 s = 2.24 Emerald 53.33 * 131.66* Indicates extremes beyond 1 standard deviation. "Winona" 45.00 110.00* Chemung 50.00 120.00 Penngift 40.00* 123.33 Chemung was markedly lower in height growth in this "Kentucky" 43.33 130.00 trial while Emerald was somewhat better in its spreading X 46.33 X 122.98 ability than the other three varieties ( table 17). Analysis of variance indicated no significant difference among varieties s 5.32 s 8.67 in respect to height or spread. Another comparative seeding of varieties was established • Departure beyond 1 standard deviation. May 9, 1967 with the varieties Emerald, Chemung, "Winona," Penngift and two accessions of "Kentucky" in replicated nur Emerald performed especially well in terms of spread in sery rows. On July 23, 1968, plantings were measured and the this trial while "Winona" was the poorest of the varieties. average height and width of each determined. The comparative performance of all varieties in this plant ing was uniformly good. The plantings were scored for aver age height and overall performance. Height does not neces Direct Seeding of Woody Plants saily indicate any inherent superiority in taller scoring varie Sumac Seed Experiments ties. The scoring for overall performance is probably a more meaningful measure for ground cover purposes ( table 17). In Minnesota, both Smooth and Staghorn Sumac frequent ly invade highway slopes. They have been regarded as a mixed blessing, a nuisance on slopes that were mowed regu larly but sometimes tolerated on long unmowed grades. Sumac Table 17. Ratings of Crownvetch seedlings grown on has often been the object of herbicidal sprays where mainten the Landscape Arboretum slope: planted April 28, 1964, ance has concentrated on the elimination of woody plants. scored September 11, 1966 The attractive summer foliage and striking autumn coloring adds to the landscape value of these plants. In winter the red fruiting "bobs" or seed heads borne on the bold open branch Seedlings ing structure add to sumacs' landscape appeal. Mean height Performance• Varieties (centimeters) rating Smooth Sumac Smooth Sumac ranges widely over the United States and Emerald 50.0 l.6t southern Canada. It tolerates a relatively broad range of pH and can thrive on subsoils as well as normal topsoils. It is Chemung 49.16 1.8 commonly seen on hot dry south-facing slopes where many Iowa ("Calmar") 49.16 1.8 other woody species find it difficult to become established. "Kentucky" 50.0 1.6 However, it favors no particular exposure. Smooth Sumac "Kentucky" 45.8 2.0 spreads vegetatively by rhizomes and single plants can even "Winona" 47.5 2.1 t tually occupy a large area. Colonies or clones, each derived Penngift from one original seedling, are readily discernible to the 45.0 2.0 trained observer who can detect the likeness of individual X 48.09 X 1.9 stems within a given colony. s 2.02 s .186 Experiments were designed to investigate some of the re quirements associated with germination and establishment of Sumac. Investigations were limited to Smooth Sumac because ' Performance rating = 1. excellent, 2. good, 3. fair. t Indicates extremes beyond 1 standard deviation. its lesser height at maturity makes it more desirable for slope plantings than the larger Staghorn Sumac. Treatments in cluded boiling water, hot water (150° F.), sulfuric acid soak, mechanical scarification, and stratification, Under the experi . While Emerald and one lot of "Kentucky" scored highest mental conditions, boiling water was found to be a safe, read m_ over~ll performance, it should again be emphasized that ily controllable, inexpensive method of seed pretreatment this entire planting developed so well that varietal differences ( Johnson et al., 1966). Further investigation will be required Were difficult to observe. before any of the treatments can be recommended on a prac Direct seeding of Crownvetch varieties in comparative ticable basis.

41 Direct Seeding of Smooth Sumac ing of forest trees and s~rubs. Properl_y treated _seed of g?od To determine the effects of planting time and seed pre quality will usually germinate but survival and final estabhsh treatment on the establishment of Smooth Sumac, a study was ment of the seedings is often too low to be of value in re designed incorporating untreated seed and seed -'?retreated vegetating bare sites. Under natural conditions seeding usually with boiling water to break down the_ seed coat re~1stance to takes place at an extraordinarily high rate. Germination may water imbibition. The procedure consisted of plantmg treated be good but losses are correspo_ndingly ?igh_ and the ultimate and untreated seeds, 5 seeds per hill respectively in hil}s 2 feet population reaches a balance with the s1tuat1on. apart with 20 hills per line at ap~ro~imatel)'. weekly mtervals The purpose of this experiment was to determine the prac beginning October 28, 1966 contmumg until freeze-up (No ticability of employing direct seeding procedures for the es vember 23, 1966) and resuming March 28, 1967. The last of tablishment of woody ground cover plants on steep slopes. A 15 plantings was made on June 5, 1967. comparison was also made of seed treat~ent and mulching A steep west facing slope was selected on 1-494 near the materials in the germination and establishment of woody County Road 60 interchange in Eden Prairie. The slope had ground covers. a cover of Smooth Bromegrass, Sweet Clover, and Leafy The experiment included twelve kinds o~ seed treatments and was laid out on the east and west facing slopes of the Spurge. . . · f Periodic checks were made in 1967 for germmat10n o Cannon Falls bypass ( table 19). Plantings were done in three fall and spring sown seeds. Competition w!th the e_xisting vege tiers on each side of the road with _seed lots randomized in tation caused the death of the few seedlmgs which had ger each tier. Planting dates were May 20, 1965 for the west bank minated as soon as dry summer weather set in. There was no and June 9 1965 for the east bank. The late planting dates survival the first year so that no conclusions could be drawn on this dry, sandy location undoubtedly contributed to the as to the effectiveness of pretreatment with boiling water. poor results. Further checks which occurred periodically until 1969 in dicated no further germination. This method for ~stablishing sumac on roadsides evidently is of no value, especially where Table 19. Cannon Falls direct seeding test: plant and there is grass competition. mulch materials used Hydroseeding of Smooth Sumac Seed Plant materials Mulch materials An experimental Smooth Sumac seeding using the Highway Department's hydroseeder was undertaken ?~ April 14, 1966, Smooth Sumac (untreated) Straw on the Ossanna Hill cut on 1-494, Eden Prame. Smooth Sumac (stratified) Wood Pulp Nineteen pounds of Smooth Sumac collected locally were Smooth Sumac (acid treated) Wood Chips pretreated by immersion in boiling water. The seed was '.1dded Autumnolive to 1,300 gallons of water in the hydroseeder and apphed to Partridgepea an area approximately 90 feet by 400 feet on the lower part Fragrant Sumac of the east facing slope. Based on 68,600 seeds per pound, an Bayberry estimated 1,300,000 seeds were applied to the area. Germ_ina Buckbrush tion tests showed 73 percent live seeded which resulted m a Sea Buckthorn seeding rate of approximately 26 live seeds per square foot. Virginia Creeper The seed was not covered or mulched, the soil being rough enough at the time of seeding to provide some covering as a result of washing. The first observations were made on April 19, 1966 using Both untreated and pretreated seed were used in t~is e~ a quadrat of 1 square foot randomly situated in the seeded periment. Pretreatment of seeds consisted of a sulfuric acid area. These observations indicated an average of 7.5 exposed soak of the hard seed coats of Smooth Sumac to bre~~ down seeds per square foot, which would account for about one the resistance to water imbibition. All seeds were st~at1f1ed for fourth of the seeds discharged into the plot. Germination was 60 days prior to sowing with the exception ?f Partndgepe~. poorer than expected. No seedlings were observed during Individual plots were 20 feet by 6 feet wit~ ~ 4 fC?ot b01 der 1966. It was not until 2 years later that seedlings of Smooth between plots. After sowing, the plots _we~e. d1v1ded ~nto three Sumac began to appear in and immediately around the hydro equal subplots, which were mulched _in~1v1~ually with straw, seeded plot. While both Smooth and Staghorn Sumac are ap wood chips, and wood fiber.* The d1stnbut10n of the mulch pearing sporadically around the Ossanna Hill cut, the concen material was randomized throughout the subplots. tration of plants in the hydroseeded areas is an indication of Best germination with Partridgepea resulted under t~e significant establishment as a result of this seeding. wood fiber, while the poorest was obtained under. straw m Chances of success and valid evaluation of the seeding are eight of the nine plots. In the top tier of the east facing slope, very limited because this area has been mowed annually. This the wood chip treatment produced slightly more seedlings than has prevented the sumac seedlings from developing and con wood fiber when scored on July 31, 1965. . , tributing to the effective cover on the slope. Untreated Smooth Sumac Buckbrush, Autumnohve, Ba)· berry, or Sea Buckthorn failed to germinate. Germination was Direct Seeding of Woody Ground Covers-Cannon Falls observed in acid treated and stratified Smooth Suma~, Frag rant Sumac, and Virginia Creeper. As ~ith the Part1dgepea, Direct seeding of woody plants offers a tempting approach germination was best under the woo~ fiber. mul~h follC?wed to cost reduction in establishing stands of such materials. The closely by wood chips. Straw was decidedly mfenor to e1!her high cost of nursery stock, high planting and maintenance wood fiber or wood chips in most plots. Up to 400 seedl~ngs costs combine to make the establishment of plantings expen of Smooth Sumac were observed in one of the wood fiber sive. If plantings could be satisfactorily established by seeding, subplots. Mortality was heavy and could be attri_bute~ to the costs would be cut. draughty nature of the sandy soil. When examined (n Sep Most research in the area of woody plant establishment tember 1965, Smooth Sumac in small numbers survived. 10 by direct seeding has been done with forest trees. With the ex only seven plots in the lower two tiers of the east fac!ng ception of the southern pines, and moderate success with Jack slope. Seedlings in the top tier and all th?st: ~n the west ~aci~! Pine, little significant success has been achieved in direct seed- slope had perished. The two plots of VIrginia Creeper m t

• A product manufactured by Conwed Co., Cloquet, Minnesota.

42 two lower tiers of the east facing slope contained a few seed plant, indicating a need for selection of plants which root with lings at this time but ultimately perished. greater ease and grow vigorously. The failure of this planting may be partially attributed to Sweetfern is a plant worthy of serious investigation in the late planting dates and the sandy soil with little water hold propagation and establishment in highway planting. With spe ing capacity. Under these site conditions, planting may have cial care, Sweetfern can be propagated by root cuttings. been more successful in late April, which would have allowed Young plants must be grown as nursery stock before trans germination during cooler weather when moisture was still planting to the field. abundantly available. Junipers comprise the only coniferous evergreen group adapted to ground cover use in northern situations. It is pos sible that more research on forms and hardiness in this group PLANT SURVEYS OF EXISTING HIGHWAY SLOPES could result in the production of new forms and clones with adaptive qualities, An example may be taken from the Skandia One objective of the research program was to determine Juniper, a hardy form of the Savin Juniper. The common what plant species were present on roadsides, the relative im Savin Juniper originated in central Europe and is not hardy. portance of various species and how their presence might be Development of similar variations may be possible in other related to maintenance practices, past and present. To obtain species if research were undertaken. With the exception of this information, vegetation composition surveys were made Japanese Shore Juniper, most junipers are not very salt toler on selected highway slopes in south central Minnesota. ant. The Japanese Shore Juniper, though salt tolerant, is not On the sites investigated the proportion of native (i.e., in hardy in Minnesota. The possibility of combining the two digenous species) plants on roadsides was found to depend on characteristics depends on further research. the age of the slope. On the older relatively undisturbed slopes the native species ranged up to 90 percent of those present MISCELLANEOUS SMALL TREES BROUGHT INTO THE while on newly established slopes they might run as low as PROGRAM 10 percent, the latter being primarily native weedy plants such as ragweeds. As a result of the broad interest in plant materials suited The native materials found on the older sites were mostly to highway use some nonground cover type plants inevitably Jong-lived perennials, a situation brought about by manage found their way into the program. These are of interest and ment which has largely excluded woody species. value but not to be equated with the ground cover species. The native materials are in large part components of the Autumnolive is a small tree related to the commonly original prairie vegetation of the state. Sound management planted ornamental Russianolive. The plant has merit for aimed at encouraging such native flora can produce stable, planting on dry alkaline soils but none of the accessions re attractive roadsides requiring minimal maintenance. ceived in this program proved to be sufficiently winter hardy in Minnesota (table 20). Sea Buckthorn, another plant related to Russianolive, is ADDITIONAL RESEARCH CONSIDERATIONS fully hardy and may be used interchangeably with Russian olive throughout southern Minnesota. Like Russianolive, the The primary effort of the program was focused on the Sea Buckthorn is a small tree suited to dry and alkaline soils. evaluation of plant materials for highway planting. A limited It is well adapted to use for screening, its silvery white foliage amount of work applied to the propagation and cultural re providing a striking visual effect during the summer months. quirements of each species. As a result, much remains to be Fruits from low-growing nearly prostrate forms of American learned about the detailed requirements of many of the lesser Plum and Western Chokecherry were collected near Boulder, known species and varieties included in this report. Colorado. These materials were grown to determine if their Information on the propagation and establishment of low habit was sufficiently heritable to make these forms plants adapted to acid soils is needed to broaden the numbers useful as seed grown varieties for possible bank planting. and use of plant materials in acid situations. Bayberry, one of Plants have not been observed sufficiently long to judge their the finest ground covers for sandy soils, is difficult to trans- potential value.

Table 20. Evaluation of small trees for. roadside planting

Hardiness Plant Plant zone Height type Evaluation and comments

Autumn olive 5 10' shrub Tolerates alkaline and salt (Elaeagnus umbellata) soils. Not sufficiently hardy in Minnesota. Sea Buckthorn 3 10' shrub Tolerates alkaline and salt (Hippophae rhamnoides) or small soils. Suitable for screening tree and background plantings on difficult sites. American Plum 3 4' shrub A low-growing variant not (Prunus americana) adequately evaluated. Western Chokecherry 3 5' shrub A low-growing variant not (Prunus virginiana var. adequately evaluated. demissa) Siberian Salttree 2 6' woody Extremely hardy, salt toler- (Halimodendron ant shrub adapted to saline or halodendron) alkaline soils. Circumneutral to saline soils, full sun. Estab- lish by transplants.

43 Ill. Establishment and Maintenance of containers should be removed prior to planting. Pressed peat containers should have the bottom removed and the top of the Plant Materials container removed to the soil line. The soil ball in containers and at the time of planting should be continually maintained This section gives a brief summary of plantings and selec in a moist condition. tion considerations. A trained landscape manager should evaluate individual situations, select plant materials, and over Balled and Burlapped Materials (evergreens) see maintenance operations. The B & B technique is used primarily with field grown evergreens. Care must be taken to lift only the ball and not GRADES AND STANDARDS the stems or trunk. Rough handling of the soil ball results in destruction of the root system and separation of roots and soil. Seed If B & B stock is not planted immediately it should Seed should be certified for purity, germination, and al mulched and maintained in a moist condition. lowable weed seed content. Proper bacterial inoculant should be specified for legume seed. PLANTING Plant Materials A soil test is recommended to determine a fertility pro All plant materials should be selected and specified ac gram for each planting site. Instructions and containers for cording to "USDA Standard for Nursery Stock" (196~). soil testing are available from county agents throughout the Woody plants are ordinarily marketed as: (1) bare root, 1.e. state. Samples may be mailed directly to the Soil Testing Lab without a soil ball around the roots; (2) balled and burlapped oratory, Department of Soil Science, University of Minnesota, (B & B), i.e. with a soil ball around the roots and (3) as con St. Paul, Minn. 55101. tainer-grown or potted stock. Topsoil should be spread to a depth of 4 to 8 inches. Till Bare root stock is commonly dug in the fall and stored ing and mixing of the _first 2-3 inches ~~ topsoil with the ~ub over-winter for spring sale and planting. B & B stock is usually soil bonds the two soil layers and facilitates water, nutnent, dug in either spring or fall for immediate planting._ Contai~er and root penetration. This practice also reduc~s the possibility or potted stock may be field planted at almost any time durmg of slides and slips after plants become estabhshed. If no soil the growing season. test is available, tilling in 0-20-0 or 0-20-20 fertilizer to a All plant materials should be specified b}'. spe~ies and depth of 5-6 inches at the rate ?~ 800 pounds per . acre is variety, size and/or age, and manner of handlmg; 1.e., bare recommended. Nitrogen (N) fertlhzers are best applied and root; B & B; or container-grown. Evergreens sh~uld never be lightly incorporated into the surface of the soil. Readily avail specified as bare root. Liners ( small rooted cuttmgs) are de able N should be applied at a rate of ½ pound actual N per signed for nursery trade and are not recommended. 1,000 square feet or at one-half the rate o_f potassi~m and The smallest size of finished, spreading type juniper nur phosphorus. When _wood chip or other org~~1c mulch 1s used, sery stock is generally offered as 15-to-18-inch spread in varie a periodic topdressmg of 10-10-10 type fert1hzer at the rate of ties such as Skandia or Pfitzer Juniper. Sizes offered may 1 pound N per 1,000 square feet is advised. In acid soils, li~e range up to 3 or 4 feet. The unit cost of larger sizes increases should be applied and tilled into the topsoil prior to plantmg rapidly. In general the smaller sizes will prove more economi according to soil test recommendations. cal if adequate post planting care is provided. Larger sizes can Topsoils used in planting hol~s for b~e root, B & B,_ ~nd be justified for quicker landscaping effect but are likely to container material should be ennched with 0-20-20 fertilizer have a higher mortality during the establishment period than at the rate of 2-3 pounds per cubic yard of soil. In shrub smaller stock. planting areas, 3-4 pounds of 0-20-20 tilled into 100 square feet of area is recommended. SOURCE OF PLANT MATERIALS Seeding Local purchase of plant materials is recommended when Topsoil should be tilled and graded pri~r to see_din_g. S_eed ever possible. Usually there are advantages to obtaining nur should be broadcast or drilled to ensure uniform d1stnbut10n. sery stock locally. This ensures local adaptation of the ma Drilling ordinarily results in a light soil covering over the seed. terials where hardiness differences exist within a species. Local Broadcast seedings should be covered lightly _by me~ns of a acquisition is particularly important for collected materials light drag or raking. Seedings must be kept m01st contmuously and materials grown from seed. after the seeds have started to germinate until seedlings are Clonal material, which includes most evergreens, can well established ( 3-4 weeks). be grown at distant locations. However, local production en Early spring and fall seedings generally give the best ~e sures proper hardening or conditioning of a plant to the sea sults. Mulching with straw at 1½-2 tons per acre tacked with sonal stresses of Minnesota's climate. asphalt has proven to be very beneficial and is recommended on all seedings. HANDLING OF PLANT MATERIALS Seed PLANTING OF NURSERY STOCK Seed should be planted immediately or stored in a cool dry All nursery stock can be planted as purchased. Holes place in a rodent proof container. Seed should never be al should be deep enough to ensure planting at the same dep!h lowed to become moist in storage. as the plants were in the nursery. Plants should be planted m Plants staggered rows across a slope. Planting distances should be determined by the type and size of plant material used _(some Bare root materials (decidious) plants spread more and faster than others), by the kmd_ of Bare root stock should be planted immediately after pur effect desired (e.g., a mass effect planting) and the time chase or removal from storage. It must be stored under cool needed to develop full cover. . moist conditions. Roots must be protected and kept moist at The soil around plants should be secured firmly aft~r all times during storage, transport, and planting. Damaged planting. Plants should be watered immediately to settle so~ roots and branches should be pruned before planting. and then mulched with a long lasting material such as woo Container-grown materials (decidious and evergreen) chips to conserve moisture. Container-grown and potted plant materials can be planted When B & B or container grown plants are used, the ~ole almost any time during the growing season. Metal and durable should be at least 6 inches larger than the ball. The subsoil at

44 the bottom of the hole should be loosened at the time of trolled by mowing. An occasional mowing of the entire plant planting. The burlap on B & B materials should be cut in sev ing will not injure such legumes as Birdsfoot Trefoil. Crown eral places at planting time. Enriched topsoil should be eased vetch, however, will be permanently injured by mowing. in gradually and firmed around the base. A depression should Dwarf Southernwood and certain other species mentioned in be left around the plant when finished in order to hold water. Recommended Varieties can be mowed with the mower set Plantings should be watered immediately and then mulched. at the highest level. Care should be exercised with the use of 2,4-D type chem ESTABLISHMENT OF PLANT MATERIALS icals around all legume and woody plantings. These chemicals can kill or severly injure nongrassy plantings under common The control of weeds, particularly during the establish application rates. ment period, is important to the welfare and appearance of a planting. Weed control can be accomplished mechanically AVAILABILITY OF PLANT MATERIALS through cultivation or chemically. Where weed conditions warrant, pretreatment of the planting site with short-lived Many plant materials recommended in this report are not sterilants such as methyl bromide or Vapam may be desirable. commonly available from commercial nurseries. Some ma In seeding a legume such as Birdsfoot Trefoil a mixture of terials are available in limited numbers from nurseries located 1 pound dalapon and ½ pound 4-(2,4-DB) per acre controls in Minnesota and other states. grassy and broadleaf weeds. It may be necessary to contract production of certain ma Dacthat• is an herbicide commonly used on ornamental terials until they become established in the nursery trade. The plants. It controls certain annual grasses and broadleaf weeds. Minnesota Nurserymen's Association will supply names of Rates suggested are 15-20 pounds in 50 gallons of water per producers interested in contract production. A supply of basic acre, which can be applied 2 days after transplanting! It is best propagation stock would have to be made available at the ini used in spring as a pre-emergence herbicide. Treflan (triflura tiation of production. Special arrangements would be required lin) may be used similarly for broadleaf weed and annual with the University of Minnesota for furnishing propagation grass control at 1 pint (light soil) to 1 quart (heavy soil) per stock. acre on preplanted stock. Treflan must be incorporated into Most of the recommended materials in limited produc the soil after application. Princep SOW ( simazine) can be tion could be readily propagated in large numbers once a used on coniferous plantings at 2-4 pounds per acre as a pre demand was established. Materials falling into this category emergent weed control. are in the cinquefoils, Dwarf Southernwood, Reynoutria Fleeceflower, etc. MAINTENANCE OF PLANT MATERIALS Many plant species are naturalized over a wide range of climatic conditions. In certain areas locally adapted races have Maintenance should be minimal after ground covers have developed. The locally adapted race may have the same ap been established ( see list of Recommended Varieties, page .. pearance as a hardier type from another area. With this in for suggestions for individual ground covers). mind, qualified plantsmen should be consulted before pur Most woody plants will require a periodic top dressing of chasing plant materials produced in states other than Minne fertilizer. Deciduous materials may be fertilized with a 1-2-2 sota. ratio fertilizer at the rate of ½-1 pound of actual N per 1,000 square feet. Evergreen materials should be fertilized with a List of References 2-1-1 or 1-1-1 ratio fertilizer at the same rate during the spring of the year. Fertilization should take place prior to June 1. American Association of Nurserymen. 1969. U.S.A. Standard Weed control may also be desirable in some plantings dur for nursery stock. USAS 260.1. 27 pp. ing the establishment period. The same materials recommend Johnson, A. G., L. E. Foote, and M. H. Smithberg. 1966. ed above may be considered. "Smooth sumac seed germination." Plant Propagator 12 Woody plantings should be designed so that mowing (3):5-8. around individual plants is unnecessary. Mulching and herbi Kelsey, H. P. and W. A. Dayton, editors. 1942. Standardized cide use can serve that purpose. Some legumes may spread plant names. J. Horace McFarland Co., Harrisburg, Penna. beyond the designated planting area and these may !le con- 675 pp.

'The inclusion of a trade name does not imply endorsement by the University of Minnesota and exclusion does not imply nonapprovai. 'Reprinted by permission; Farm Technology, Vol. 25 (3), 1969.

45 Figure 2. Bearberry Figure 5. Redosier Dogwood

Figure 3. Crownvetch Figure 6. Arcadia Juniper

Figure 4. Tawny Daylily Figure 7. Skandia Juniper 46 Figure 8. Creeping Juniper Figure 11. Pfitzer Juniper

Figure 9. Japanese Garden Juniper Figure 12. Sargent Juniper

Figure 10. Oldfield or Prostrate Juniper Figu re 13. Cicer Milkvetch 47 Figure 14. Kamchatka Rose Figure 17. Birdsfoot Trefoil

Figure 15. Fragrant Sumac Figure 18. Prostrate Alfalfa

Figure 16. Smooth Sumac Figure 19. Pirone Alfalfa 48 Figure 20. Sicklepod Alfalfa Figure 23. Allegheny Blackberry

Figure 21. Barrenstrawberry Figure 24. Georgia Bushhoneysuckle

Figure 22. Bayberry Figure 25. Dwarf Spring Cinquefoil 49 Figure 29. White Clover

Figure 27. Friedrichseni Cinquefoil Figure 30. Zigzag Clover

Figure 28. Irving Cinquefoil Figure 31. Cowberry 50 Figure 32. Thicket Creeper Figure 35. Lilac Honeysuckle

Figure 33. Virginia Creeper Figure 36. Rush Lespedeza

Figure 34. Reynoutria Fleeceflower Figure 37. Sicklepod Milkvetch 51 Figure 38. India Mockstrawberry Figure 41. Perennial Peavine

Figure 39. Partridgepea Figure 42. Herbaceous Periwinkle

Figure 40. Russian Peashrub Figure 43. Quicksilver Petunia 52 Figure 44. Alaska Phlox Figure 47. Japanese Trailing Raspberry

Figure 45. Maiden Pink Figure 48. Fringed Sage

Figure 46. Magic Carpet Polygonum Figure 49. Common Snowberry 53 Figure 50. Dwarf Southernwood

Figure 51. Billiard Spirea Figure 54. Two-row Stonecrop

Figure 52. Dwarf Garland Spirea Figure 55. Sweetfern 54 Table 3. Plants not recommended or not sufficiently evaluated for Minnesota roadsides (continued)

Plant Plant Evaluation, comments, and Name zone height Type availability

PEAVINE, GROUNDNUT 3 3' vine Not as strong growing as Flat Pea- (Lathyrus tuberosus) vine. May be toxic to cattle.

PEAVINE, PERENNIAL 3 3' vine Herbaceous ground cover. Does (Lathyrus sativus) not produce adequate cover.

PINE, BROOMED JACK 2 5' woody D\•:a:f co~pact shrubby evergreen. (Pinus banksiana "Broom") Ac1d1c to circumneutral soils, full sun.

PLANTAINLILY 4 1' herb* Rare possibility of use in shady (Hosta sp.) sites. Part or total shade.

RASPBERRY, WESTERN RED 3 2' woody Western form of common rasp- (Rubus idaeus aculeatissimus) berry.

ROSE, DAHURIAN 2 4' spreading Promising rapidly spreading shrub (Rosa davurica) shrub rose suited to most well-drained soils. Insufficient evaluation. i\ ROSE, DROPHIP 5 4' woody Not hardy in Minnesota. (Rosa pendulina)

ROSE, MAX GRAF 5 3' trailing Not fully hardy in Minnesota. (Rosa 'Max Graf') woody

~ ROSE, MEMORIAL 5 2' half ever- Hardy only in southern Minnesota. (Rosa wich11raiana) green Trailing stems. shrub

SAGE, JERUSALEM 4 3' herb* Insufficient evaluation. Coarse-tex- (Phlomis tuberosa) tured plant; spreads by suckering.

ST. JOHNSWORT, AARONSBEARD 5 1' herb"' Not hardy in Minnesota. (Hypericum calycinum)

II Classified as noxious weed. ST. JOHNSWORT, COMMON 4 1½' herb* (Hypericum perforatum)

Not hardy in Minnesota. ST. JOHNSWORT, HIDCOTE 6 2' woody (Hypericum patulum 'Hidcote')

3' woody Shrub difficult to establish. Hardy ST. JOHNSWORT, KALM 3 in Minnesota. Acid to circumneu- (Hypericum kalmianum) tral soils, full sun or part shade. Establish from transplants. Avail- ablity limited.

Not hardy in Minnesota ST. JOHNSWORT, OLYMPIC 5 6" subshrub (Hypericum olympicum) 27 Figure 56. Bird Vetch Figure 59. Adamsneedle Yucca

Figure 60. 1963 plantings on 1-494

Figure 61. Crownvetch plantings in Landscape Arboretum 55