Index of Species Information

SPECIES:  Rudbeckia hirta


SPECIES: Rudbeckia hirta
AUTHORSHIP AND CITATION : Walsh, Roberta A. 1994. Rudbeckia hirta. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: [].

ABBREVIATION : RUDHIR SYNONYMS : NO-ENTRY SCS PLANT CODE : RUHI2 RUHIA RUHIB RUHIF RUHIP COMMON NAMES : black-eyed Susan TAXONOMY : The currently accepted scientific name of black-eyed Susan is Rudbeckia hirta L. [28,35]. It is in the sunflower family (Asteraceae). Recognized varieties are as follows: R. h. var. hirta R. h. var. angustifolia (Moore) Perdue [12,55] R. h. var. brittonii (Small) Fernald [48,55] R. h. var. floridana (Moore) Perdue [55,61] R. h. var. pulcherrima Farwell [35,55] LIFE FORM : Forb FEDERAL LEGAL STATUS : No special status OTHER STATUS : NO-ENTRY


SPECIES: Rudbeckia hirta
GENERAL DISTRIBUTION : Black-eyed Susan is found throughout most of North America, particularly east of the Rocky Mountains [45,51]. It has been sporadically introduced into the Pacific Northwest [35]. Black-eyed Susan has also been introduced in Europe as an ornamental and can now be found growing wild in seminatural stands [57]. Rudbeckia hirta var. hirta occurs from Pennsylvania to Georgia and sparingly north to Maine and west to Illinois [26]. Rudbeckia hirta var. angustifolia is in the South [28]. Rudbeckia hirta var. brittonii is found in the southeastern United States [48,55]. Rudbeckia hirta var. floridana is found in central Florida [61]. Rudbeckia hirta var. pulcherrima is widespread, especially in disturbed habitats [26]. ECOSYSTEMS : FRES10 White - red - jack pine FRES11 Spruce - fir FRES12 Longleaf - slash pine FRES13 Loblolly - shortleaf pine FRES14 Oak - pine FRES15 Oak - hickory FRES17 Elm - ash - cottonwood FRES18 Maple - beech - birch FRES19 Aspen - birch FRES20 Douglas-fir FRES21 Ponderosa pine FRES23 Fir - spruce FRES30 Desert shrub FRES35 Pinyon - juniper FRES37 Mountain meadows FRES38 Plains grasslands FRES39 Prairie FRES41 Wet grasslands STATES : AL AR CA CO CT FL GA IL IN IA KS KY LA ME MD MA MI MN MS MO MT NE NH NJ NM NY NC ND OH OK PA SC SD TN TX VT VA WA WV WI WY AB BC MB NB NF NS ON PQ SK MEXICO BLM PHYSIOGRAPHIC REGIONS : 2 Cascade Mountains 3 Southern Pacific Border 5 Columbia Plateau 8 Northern Rocky Mountains 10 Wyoming Basin 13 Rocky Mountain Piedmont 14 Great Plains 15 Black Hills Uplift 16 Upper Missouri Basin and Broken Lands KUCHLER PLANT ASSOCIATIONS : K005 Mixed conifer forest K007 Red fir forest K012 Douglas-fir forest K015 Western spruce - fir forest K017 Black Hills pine forest K018 Pine - Douglas-fir forest K023 Juniper - pinyon woodland K040 Saltbush - greasewood K066 Wheatgrass - needlegrass K072 Sea oats prairie K073 Northern cordgrass prairie K074 Bluestem prairie K081 Oak savanna K082 Mosaic of K074 and K100 K083 Cedar glades K084 Cross Timbers K095 Great Lakes pine forest K096 Northeastern spruce - fir forest K098 Northern floodplain forest K099 Maple - basswood forest K100 Oak - hickory forest K102 Beech - maple forest K104 Appalachian oak forest K106 Northern hardwoods K107 Northern hardwoods - fir forest K110 Northeastern oak - pine forest K111 Oak - hickory - pine forest K112 Southern mixed forest SAF COVER TYPES : 1 Jack pine 14 Northern pin oak 15 Red pine 16 Aspen 19 Gray birch - red maple 20 White pine - northern red oak - red maple 26 Sugar maple - basswood 31 Red spruce - sugar maple - beech 32 Red spruce 33 Red spruce - balsam fir 37 Northern white-cedar 40 Post oak - blackjack oak 42 Bur oak 45 Pitch pine 46 Eastern redcedar 52 White oak - black oak - northern red oak 53 White oak 55 Northern red oak 60 Beech - sugar maple 62 Silver maple - American elm 70 Longleaf pine 71 Longleaf pine - scrub oak 76 Shortleaf pine - oak 78 Virginia pine - oak 80 Loblolly pine - shortleaf pine 83 Longleaf pine - slash pine 84 Slash pine 107 White spruce 110 Black oak 207 Red fir 210 Interior Douglas-fir 220 Rocky Mountain juniper 237 Interior ponderosa pine 239 Pinyon - juniper 251 White spruce - aspen SRM (RANGELAND) COVER TYPES : NO-ENTRY HABITAT TYPES AND PLANT COMMUNITIES : In southwest Michigan black-eyed Susan occurs in wet prairie in association with goldenrods (Solidago spp.), sedges (Carex spp.), Indian grass (Sorghastrum nutans), marsh fern (Thelypteris palustris), queen-of-the-prairie (Filipendula rubra), purple meadowrue (Thalictrum dasycarpum), prairie cordgrass (Spartina pectinata), and cowbane (Oxypolis pectinata) [40]. Associates of black-eyed Susan in tallgrass prairie in central Illinois include leadplant (Amorpha canescens), sawtooth sunflower (Helianthus grosseserratus), stiff sunflower (Helianthus rigidus), rattlesnake master (Eryngium yuccifolium), New Jersey tea (Ceanothus americanus), and flowering spurge (Euphorbia corollata) [38]. Associates of black-eyed Susan in remnant upland tallgrass prairie in west-central Missouri include eastern red-cedar (Juniperus virginiana), dewberry (Rubus flagellaris), chokecherry (Prunus virginiana), buck brush (Symphoricarpos orbiculatus), leadplant (Amorpha canescens), and wild snowball (Ceanothus americanus) [37]. Associates of black-eyed Susan in montane meadow grasslands within the Rocky Mountain, Sierran, and Madrean montane conifer forests include bracken fern (Pteridium aquilinum), California false-hellebore (Veratrum californicum), monkey flower (Mimulus nasutum), mountain brome (Bromus marginatus), and iris (Iris missouriensis) [10]. Associates of black-eyed Susan in Sequoia National Park, California, on sites adjacent to a giant sequoia (Sequoiadendron giganteum) grove include California wood fern (Dryopteris arguta), beaked hazel (Corylus cornuta), American trailplant (Adenocaulon bicolor), incense-cedar (Libocedrus decurrens), bush chinquapin (Chrysolepis sempervirens), Richardson geranium (Geranium richardsonii), California buckeye (Aesculus californica), white hedgenettle (Stachys albens), white fir (Abies concolor), sugar pine (Pinus lambertiana), Sierra gooseberry (Ribes roezlii), and western cowbane (Oxypolis occidentalis) [3].


SPECIES: Rudbeckia hirta
IMPORTANCE TO LIVESTOCK AND WILDLIFE : NO-ENTRY PALATABILITY : In the western Cross Timbers of northern Texas in 1944, black-eyed Susan was lightly grazed by cattle during the last half of April, heavily grazed during May, and lightly grazed during the first half of June. It was not grazed at any other time [20]. In southeastern Minnesota white-tailed deer grazed black-eyed Susan plants which had been transplanted as seedlings into test plots in the spring of 1983. Thirty-six percent of black-eyed Susan plants were grazed in 1983, and 8 percent in 1984. No plant was grazed more than once. Eastern cottontails and thirteen-lined ground squirrels were observed in the study area, but they did not make use of black-eyed Susan [21]. NUTRITIONAL VALUE : NO-ENTRY COVER VALUE : NO-ENTRY VALUE FOR REHABILITATION OF DISTURBED SITES : Black-eyed Susan is recommended for restoration of disturbed areas and prairies [51]. Black-eyed Susan seeds are available for restoration and conservation efforts from the USDA Soil Conservation Service Plant Materials Center at Corning, New York [58]. Roadside sites: Black-eyed Susan seeds or plants were used along highways in Wisconsin as part of a natural tallgrass prairie roadside restoration project. Black-eyed Susan gave excellent response to all attempted propagation methods: direct seeding on the field site; transplanting seedlings; and tranplanting year-old plants [46]. Black-eyed Susan, along with other native wildflowers, was used in Massachusetts to restore a roadside site that had shallow, infertile soil, poor moisture retention, and hostile exposure. After 4 years, black-eyed Susan was one of few survivors at the site [1]. Black-eyed Susan was used in the rehabilitation of a sand and gravel borrow-pit in Greene County, Ohio in 1986 and 1987. Black-eyed Susan was inconspicuous and aboveground growth was slow the first summer, but during the second year (1987) it flowered. On the drier, less fertile sites black-eyed Susan flowered in 1988, even though it was still quite small [14]. Mine sites: Black-eyed Susan, along with other native prairie forbs and grasses, was planted on iron mine tailings in west-central Wisconsin. The tailings are sandy loam in texture, lack essential nutrients, are very low in organic matter, and have an average pH of 8.5. Seed was broadcast by hand, raked in, and mulched. No artificial watering or weeding was done. Of the black-eyed Susan seeds planted, 6.8 percent produced seedlings. Growth was slow, but by the second growing season, many of the plants were flowering. Black-eyed Susan showed very little response to any fertilizer treatment [32]. Prairie sites: Black-eyed Susan was used as a cover crop to protect other forb and grass seedlings in a north-central Illinois oldfield prairie restoration project [8]. Black-eyed Susan was used in a seeding effort on open upland and drier southwest-facing slopes around groves and draws of hickories (Carya spp.) and oaks (Quercus spp.) in degraded tallgrass savanna in northwest Illinois. In October and November of 1988, seeds were hand broadcast. By fall, 1991, there were seedlings and mature black-eyed Susan plants [9]. OTHER USES AND VALUES : Black-eyed Susan is used as a garden ornamental [51]. The leaves of black-eyed Susan are used to make a tea that is said to be a diuretic, with some cardiac stimulation properties [45]. The Forest Potawatomis treated colds with a tea prepared from the roots of black-eyed Susan [4]. OTHER MANAGEMENT CONSIDERATIONS : Black-eyed Susan may be an indicator of range condition. In the western Cross Timbers of northern Texas on fine sandy loam soil, black-eyed Susan was not present on range in excellent and good condition, had coverage of 2 percent on range in fair condition, and had coverage of 4 percent on range in poor condition [20]. The Missouri grass glades were overgrazed from the late 1800's until the 1960's. By the 1930's on overgrazed open range the composition of the once productive prairie glades had changed to a community of soft chess (Bromus mollis) and black-eyed Susan [42]. Tallgrass prairie in north-central Oklahoma was subjected to short-duration grazing schedules from 1985 to 1988. Black-eyed Susan did not respond to different grazing schedules, but did fluctuate in numbers in response to environmental conditions influencing its establishment [25]. Black-eyed Susan was grazed by white-tailed deer in southeastern Minnesota in 1983 and 1984. The grazing did not significantly affect seedling survival in wet years. However, under drought conditions grazed plants might not be able to resume growth sufficiently to survive winter or compete successfully with annuals the following spring [21]. Herbivory may decrease seed yield from black-eyed Susan. Black-eyed Susan plants in a pasture in southern Oklahoma were infested with the silvery checkerspot butterfly (Nymphalidae) caterpillar during the summer of 1981. Heads from infested plants produced 50 percent fewer seeds than did heads from uninfested plants. Dispersion of black-eyed Susan plants may decrease infestation because of the limited distances the caterpillars can travel [47]. Fertilization of black-eyed Susan is probably not effective [27,32]. Black-eyed Susan may be extremely sensitive to ozone exposure. More than 50 percent of black-eyed Susan plants showed foliage injury in response to the ambiant ozone levels which occurred in the Great Smoky Mountains in 1989. With ozone exposure twice ambient level, injury was greater than 90 percent [30]. Black-eyed Susan may be a good indicator species for soil cadmium. In northwestern Indiana urban-industrial regions the soil is contaminated with cadmium and other heavy metals. Black-eyed Susan seed germination was reduced in proportion to additions of soil cadmium [62].


SPECIES: Rudbeckia hirta
GENERAL BOTANICAL CHARACTERISTICS : Black-eyed Susan is a native, warm-season, annual, biennial or short-lived perennial forb [26,34]. It has one to a few stems [4] 12 to 40 inches (0.3-1.0 m) tall [26], which are erect and sometimes sparingly branched [33]. The lower leaves are 2 to 6 inches (5-15 cm) long [28], alternate and petioled [34]. The upper leaves are mostly sessile [26]. The inflorescences are few to many flower heads on peduncles 2 to 8 inches (5-20 cm) long [34]. The fruit is an achene 0.06 inches (1.5 mm) long; there is no pappus [33]. Black-eyed Susan has a taproot or a cluster of fibrous roots [28]. It is a mycorrhizal species [43]. RAUNKIAER LIFE FORM : Hemicryptophyte REGENERATION PROCESSES : Black-eyed Susan reproduces sexually by seed [4,28]. It is pollinated by bees and flies [15,22]. It also reproduces vegetatively [56] by sprouting from the root crown [48]. In remnant tallgrass prairie in central Illinois, black-eyed Susan seeds made up 2.4 percent of germinable seeds found in the seedbank. Fifty percent of black-eyed Susan seeds were in the upper 0.8 inches (2 cm) of soil; the rest were in the next 3 inches (8 cm) of soil. The seeds occurred in high-density clumps rather than being randomly dispersed. Black-eyed Susan was a very minor component of the vegetational cover. There were more black-eyed Susan seeds in the seedbank than would be predicted by its importance value [38]. Black-eyed Susan seed germination varies with area and time of collection, and with germination conditions. Black-eyed Susan seeds were collected from wild seed sources in central Wisconsin in the fall of 1976. The seeds were given cold, dry stratification for at least 2 months, before germination testing. Germination ranges were 0 to 38 percent. When grown in soil in 1977, none germinated; in 1978, germination in soil ranged from 10 to 24 percent. The higher rate in 1978 was probably due to reduction in dormancy and to higher germination temperatures than in 1977. Light had no marked effect on the germination of black-eyed Susan seeds in this study. Wild black-eyed Susan had a very wide range of Pure Live Seed values [31]. In a germination study of Wisconsin tallgrass prairie plants, seeds were collected from the southern tier of Wisconsin counties. With 3 months cold stratification, black-eyed Susan had a maximum of 46 percent germination. However, germination values for seeds collected in different years fluctuated greatly. In some years seeds would germinate even though unstratified [29]. In trembling aspen (Populus tremuloides)-dominated vegetation in western Colorado, black-eyed Susan seeds were collected September 2-3, 1981. Germination tests were conducted within 6 months of collection. Germination rates were very low in the absence of light and without stratification. Germination rates ranged from 24 to 36 percent for moistened seeds grown in light and stratified 30 to 120 days [36]. SITE CHARACTERISTICS : Black-eyed Susan is found on clayey loam to sandy loam soils. It has low to moderate water requirements, and grows in full sun to partial shade [51]. It is found in plains and open woods [18,19], sunny roadsides and meadows [57], sandhills and bogs [12], and disturbed places [35]. Black-eyed Susan occurs at the following elevations: Elevation (feet) Elevation (meters) CA 328-3,937 100-1,200 [34] CO 5,000-9,500 1,524-2,896 [17,33] WY 8,200 2,500 [17]. SUCCESSIONAL STATUS : Facultative Seral Species Black-eyed Susan is considered a pioneer species [31], and can be dominant in early stages of succession [50]. Black-eyed Susan is part of the weed stage of abandoned fields in central Oklahoma and southeastern Kansas [59]. At the establishment of the Curtis Prairie in south-central Wisconsin between 1936 and 1941, black-eyed Susan plants were left intact, as they already occurred in some fields. They persisted a short time, spreading opportunistically into other areas. Areas originally dominated by black-eyed Susan were invaded extensively by various more aggressive species [52]. In a tallgrass prairie establishment effort in southern Wisconsin, begun in 1974, black-eyed Susan appeared in 1975, though it had not been seeded. It was abundant in the surrounding area, however [60]. SEASONAL DEVELOPMENT : Black-eyed Susan is able to flower its first year [28], but flowers more prolifically its second year. By the end of the first year it may begin vegetative reproduction, and show a distinct "bunching" effect with 2 or more shoots [46]. Topgrowth dies back each year [36,42]. Biennial and perennial forms sprout the next spring from the root crown [48]. Black-eyed Susan initiates growth in late spring and becomes dormant by early fall [2]. Black-eyed Susan flowering times are: Begin Peak End Flowering Flowering Flowering FL May ---- October [12] IL June ---- September [44] KS June ---- August [4] MI June ---- August [22] MN June July July [15] MO June ---- August [37] NC May ---- July [48] ND July July August [11] SC May ---- July [48] TX June ---- ---- [20] WI June ---- August [16] Great Plains May ---- September [28] Northeast US June ---- October [26].


SPECIES: Rudbeckia hirta
FIRE ECOLOGY OR ADAPTATIONS : Black-eyed Susan probably has good fire tolerance in the dormant state, since it reproduces vegetatively from the root crown [48,56]. It produces numerous small seeds [11] and can establish on burned sites. Black-eyed Susan thrives in the open, sunny conditions [31,51] created by fire. It may be an initial on-site colonizer since its seeds are found up to 4 inches (10 cm) or deeper in the seedbank [38]. However, no information was available on seed tolerance to heat or length of seed viablility in the seedbank. FIRE REGIMES : Find fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find Fire Regimes". POSTFIRE REGENERATION STRATEGY : Initial-offsite colonizer (off-site, initial community) Caudex, growing points in soil


SPECIES: Rudbeckia hirta
IMMEDIATE FIRE EFFECT ON PLANT : Black-eyed Susan is probably top-killed by fire during the growing season. It may survive by sprouting from the root crown [56]. DISCUSSION AND QUALIFICATION OF FIRE EFFECT : NO-ENTRY PLANT RESPONSE TO FIRE : Black-eyed Susan does not respond uniformly to burning. Depending on season of burning and local conditions, it often establishes successfully; existing populations may either increase or decrease in abundance. In south-central New York wildfires burned goldenrod (Solidago spp.)- poverty oatgrass (Danthonia spicata) fields in the springs of 1962, 1963, and 1964. Adjacent burned and unburned areas were measured for vegetative response 10 to 26 months after the fires. The average frequency of black-eyed Susan in unburned areas was 29 percent; in burned areas it was 2 percent [54]. In southwestern Missouri after a decade of prescribed burning on glade grasslands black-eyed Susan had decreased in abundance [42]. Black-eyed Susan seeds were broadcast in the fall of 1988 on sites in tallgrass oak savanna in northwestern Illinois. Consecutive spring prescribed fires were conducted in 1989, 1990, and 1991. By the fall of 1991 there were both seedlings and mature plants of black-eyed Susan on burned sites [9]. Black-eyed Susan decreased with repeated dormant season prescribed fire on one test plot in south-central Wisconsin, but increased every year in another field subjected to the same treatment [39]. In south-central Wisconsin the Curtis Prairie has had a biennial burning schedule since 1950, one-third being burned one year and the other two-thirds the following year. Black-eyed Susan was not present in 1951, but had appeared in small numbers by 1961. An extended growing season on the burned prairie appears to enhance presence of black-eyed Susan. During the spring, daytime temperatures are substantially warmer on the burned than on the unburned prairie, where the litter layer retards soil warming. The burned surface also cools faster at night. These effects are most pronounced in May and June [2] Black-eyed Susan in tallgrass prairie in eastern Nebraska on silty clay loam was burned in early May, early July, and mid-September, 1983. Plots were sampled in the fall of 1983, 1984, and 1986. Burning, particularly summer and fall burning in years with adequate precipitation, resulted in higher black-eyed Susan seedling establishment than occurred without burning. In dry years burning reduced seedling establishment. Black-eyed Susan cover also increased with summer and fall burning; cover decreased without burning [7]. Black-eyed Susan on a poor condition prairie range site in north-central Oklahoma was burned April 1, 1965-1967, in conditons where the soil was moist and the fire burned against a 5 to 10 mile-per-hour (8-16 k/h) breeze. Matched unburned plots were mowed earlier in the spring, and the residue removed. In the spring of 1966, black-eyed Susan flowered profusely on unburned plots, but was absent on burned plots [27]. The Research Project Summary, Herbaceous responses to seasonal burning in experimental tallgrass prairie plots provides information on postfire response of black-eyed Susan in experimental prairie plots that was not available when this species review was originally written. DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : NO-ENTRY FIRE MANAGEMENT CONSIDERATIONS : NO-ENTRY


SPECIES: Rudbeckia hirta
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[434] 6. Betz, Robert F.; Lamp, Herbert F. 1989. Species composition of old settler silt-loam prairies. In: Bragg, Thomas B.; Stubbendieck, James, eds. Prairie pioneers: ecology, history and culture: Proceedings, 11th North American prairie conference; 1988 August 7-11; Lincoln, NE. Lincoln, NE: University of Nebraska: 33-39. [14016] 7. Bragg, Thomas B. 1991. Implications for long-term prairie management from seasonal burning of loess hill and tallgrass prairie. In: Nodvin, Stephen C.; Waldrop, Thomas A., eds. Fire and the environment: ecological and cultural perspectives: Proceedings of an international symposium; 1990 March 20-24; Knoxville, TN. Gen. Tech. Rep. SE-69. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station: 34-44. [16631] 8. Branhagen, Alan J. 1990. Gravel prairie, sedge meadow and fen restoration underway at Kieselberg Forest Preserve. Restoration & Management Notes. 8(2): 102-103. [14157] 9. Bronny, Christopher. 1992. 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[820] 19. Dorn, R. D. 1977. Manual of the vascular plants of Wyoming. New York: Garland Publ. 2 vols. [21082] 20. Dyksterhuis, E. J. 1948. The vegetation of the western Cross Timbers. Ecological Monographs. 18(3): 326-376. [3683] 21. Englund, Judy Voigt; Meyer, William J. 1986. The impact of deer on 24 species of prairie forbs. In: Clambey, Gary K.; Pemble, Richard H., eds. The prairie: past, present and future: Proceedings, 9th North American prairie conference; 1984 July 29 - August 1; Moorhead, MN. Fargo, ND: Tri-College University Center for Environmental Studies: 210-212. [3575] 22. Evans, Francis C. 1986. Bee-flower interactions on an old field in southeastern Michigan. In: Clambey, Gary K.; Pemble, Richard H., eds. The prairie: past, present and future: Proceedings, 9th North American prairie conference; 1984 July 29 - August 1; Moorhead, MN. Fargo, ND: Tri-College University Center for Environmental Studies: 103-109. [3538] 23. Eyre, F. H., ed. 1980. Forest cover types of the United States and Canada. Washington, DC: Society of American Foresters. 148 p. [905] 24. Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; [and others]. 1977. Vegetation and environmental features of forest and range ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of Agriculture, Forest Service. 68 p. [998] 25. Gillen, Robert L.; McCollum, F. Ted; Hodges, Mark E.; [and others]. 1991. Plant community responses to short duration grazing in tallgrass prairie. Journal of Range Management. 44(2): 124-128. [14135] 26. Gleason, Henry A.; Cronquist, Arthur. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. 2nd ed. New York: New York Botanical Garden. 910 p. [20329] 27. Graves, James E.; McMurphy, Wilfred E. 1969. Burning and fertilization for range improvement in central Oklahoma. Journal of Range Management. 22(3): 165-168. [3717] 28. Great Plains Flora Association. 1986. Flora of the Great Plains. Lawrence, KS: University Press of Kansas. 1392 p. [1603] 29. Greene, H. C.; Curtis, J. T. 1950. Germination studies of Wisconsin prairie plants. American Midland Naturalist. 43(1): 186-194. [4086] 30. Hacker, David; Renfro, James. 1992. Great Smoky Mountain plants studied for ozone sensitivity. Park Science. 12(1): 6-7. [17788] 31. Halinar, Marlene. 1981. Germination studies and purity determinations on native Wisconsin prairie seeds. In: Stuckey, Ronald L.; Reese, Karen J., eds. The Prairie Peninsula--in the "shadow" of Transeau: Proceedings, 6th North American prairie conference; 1978 August 12-17; Columbus, OH. Ohio Biological Survey Biological Notes No. 15. Columbus, OH: Ohio State University, College of Biological Sciences: 227-231. [3433] 32. Hardell, Julie; Morrison, Darrell G. 1983. Response of prairie species planted on iron ore tailings under different fertilization levels. In: Kucera, Clair L., ed. Proceedings, 7th North American prairie conference; 1980 August 4-6; Springfield, MO. Columbia, MO: University of Missouri: 287-292. [3230] 33. Harrington, H. D. 1964. Manual of the plants of Colorado. 2d ed. Chicago: The Swallow Press Inc. 666 p. [6851] 34. Hickman, James C., ed. 1993. The Jepson manual: Higher plants of California. Berkeley, CA: University of California Press. 1400 p. [21992] 35. Hitchcock, C. Leo; Cronquist, Arthur. 1973. Flora of the Pacific Northwest. Seattle, WA: University of Washington Press. 730 p. [1168] 36. Hoffman, George R. 1985. Germination of herbaceous plants common to aspen forests of western Colorado. Bulletin of the Torrey Botanical Club. 112(4): 409-413. [3267] 37. Hurd, Richard M.; Christisen, Donald M. 1975. Ecology study of Friendly Prairie, Missouri. In: Wali, Mohan K., ed. Prairie: a multiple view. Grand Forks, ND: University of North Dakota Press: 89-102. [4432] 38. Johnson, Ronald G.; Anderson, Roger C. 1986. 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