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SPECIES:  Danthonia compressa
Flattened oatgrass. Image hosted by USDA-NRCS PLANTS Database, used with permission of Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York. Vol. 1: 221.


SPECIES: Danthonia compressa
AUTHORSHIP AND CITATION: Carey, Jennifer H. 1994. Danthonia compressa. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: []. Revisions: On 2 October 2018, the common name of this species was changed in FEIS from: mountain oatgrass to: flattened oatgrass. Images were also added.
ABBREVIATION: DANCOM SYNONYMS: NO-ENTRY NRCS PLANT CODE: DACO COMMON NAMES: flattened oatgrass mountain oatgrass slender oatgrass TAXONOMY: The scientific name of flattened oatgrass is Danthonia compressa Austin [10,12,20]. It is in the family Poaceae. There are no currently accepted infrataxa. Flattened oatgrass may intergrade with poverty grass (Danthonia spicata), a closely related species [4,12]. LIFE FORM: Graminoid FEDERAL LEGAL STATUS: No special status OTHER STATUS: NO-ENTRY


SPECIES: Danthonia compressa
GENERAL DISTRIBUTION: Flattened oatgrass occurs in the eastern United States and southeastern Canada. It occurs from extreme southeastern Ontario east through southern Quebec to Nova Scotia and south through New England and the Appalachian Mountain region to northern Georgia. In the southeastern United States, flattened oatgrass is restricted to the Appalachian Mountains [10,12,20].
Western (left) and eastern (right) distributions of flattened oatgrass. Maps courtesy of USDA, NRCS. 2018. The PLANTS Database. National Plant Data Team, Greensboro, NC. [2018, October 2] [24].
   FRES15  Oak - hickory

     CT  DE  GA  KY  ME  MD  MA  NH  NJ  NY
     NC  OH  PA  RI  SC  TN  VT  VA  WV  NB
     NS  ON  PQ


   K100  Oak - hickory forest
   K104  Appalachian oak forest



Flattened oatgrass occurs in forest openings, open woods, and mountain

Flattened oatgrass is dominant in grassy balds of the southern
Appalachian Mountains.  Other herbaceous plants occurring in grassy
balds include redtop (Agrostis alba), timothy (Phleum pratense), Canada
bluegrass (Poa compressa), Kentucky bluegrass (P. pratense), red fescue
(Festuca rubra), five-fingers (Potentilla canadensis), and sheep sorrel
(Rumex acetosella) [4,18,26,27]

On the Allegheny Plateau in Pennsylvania, deciduous forests which failed
to regenerate after logging support a dense groundcover of flattened
oatgrass, rough goldenrod (Solidago rugosa), tall flat-topped white
aster (Aster umbellatus), and bracken fern (Pteridium aquilinum) [13].

Flattened oatgrass is listed as a dominant species in the following

Vegetation of the Great Smoky Mountains [27]


SPECIES: Danthonia compressa
IMPORTANCE TO LIVESTOCK AND WILDLIFE: Flattened oatgrass is not considered a regionally important forage species [11,17], although it is an important pasture grass in the Appalachian highlands [4,6]. PALATABILITY: NO-ENTRY NUTRITIONAL VALUE: NO-ENTRY COVER VALUE: NO-ENTRY VALUE FOR REHABILITATION OF DISTURBED SITES: NO-ENTRY OTHER USES AND VALUES: NO-ENTRY OTHER MANAGEMENT CONSIDERATIONS: The dense growth habit and competitive nature of flattened oatgrass restricts tree seedling establishment [26]. Where tree establishment is desired, herbicides easily control existing flattened oatgrass. Glyphosate does not impede germination of residual dormant seeds, but Bromacil delays germination for more than 1 year [13]. Flattened oatgrass is host to the systemic parasitic fungus Atkinsonella hypoxylon [6].


SPECIES: Danthonia compressa
GENERAL BOTANICAL CHARACTERISTICS: Flattened oatgrass is a native, perennial bunchgrass. The culms are slender, compressed, sometimes decumbent, and 12 to 32 inches (30-80 cm) tall. The leaves are mostly at or near the base and up to 8 to 10 inches (20-25 cm) long. The inflorescence is a panicle; slender branches bear two or three spikelets. The awn is bent and 0.2 to 0.3 inches (0.6-0.8 cm) long [4,10,12,20]. RAUNKIAER LIFE FORM: hemicryptophyte REGENERATION PROCESSES: Flattened oatgrass reproduces by seed. Large amounts of seed are produced annually, some of which remain dormant in the litter for at least several years [13]. Flattened oatgrass also sprouts from perennating buds at the base of the culms. In two populations in North Carolina, flattened oatgrass produced an average of 50 percent cleistogamous flowers [6]. SITE CHARACTERISTICS: In the southern Appalachians, flattened oatgrass is a frequent species on grassy balds which occupy well-drained sites on ridges, broad slopes, and dome-shaped summits between 5,000 and 6,000 feet (1,500-1,800 m) in elevation. Grassy balds occur on slopes of all aspects but are most commonly found on south, southwest, and west aspects. Flattened oatgrass grows on dry sites but is susceptible to drought [19,26]. On wetter areas of grassy balds, flattened oatgrass dominance gives way to sedges (Carex spp.) [26]. SUCCESSIONAL STATUS: Flattened oatgrass grows in full sun and in open woods. It does not persist under closed canopies [4]. It establishes on disturbed sites including recently logged and burned areas [14,18]. Grassy balds are persistent successional communities. The origin of grassy balds is not fully understood, but former forests may have died from ice storms, blow downs, fire, or climate change. Woody species establishment is often delayed on these sites by dense herbaceous cover, harsh environment, fire, and/or grazing [3,19]. Grassy balds in the Appalachian Mountains are succeeded by Rhododendron spp. thickets, American green alder (Alnus viridis ssp. crispa) thickets, or spruce (Picea spp.)-fir (Abies spp.) forests. A dense carpet of moss (Polytrichum commune) advances into the grassy bald at the edge of the spruce-fir forest and suppresses flattened oatgrass [5]. SEASONAL DEVELOPMENT: Flattened oatgrass generally flowers from June to August [20]. In North Carolina, flattened oatgrass flowers from mid-June to early July [4].


SPECIES: Danthonia compressa
FIRE ECOLOGY OR ADAPTATIONS: Flattened oatgrass occurs in oak (Quercus spp.) woods and grassy mountain meadows which occasionally experience either lightning or human-caused fire. Lightning commonly strikes the peaks and ridges of the southern Appalachian Mountains from April through August [1]. Grassy balds in the Pisgah National Forest of North Carolina respond favorably to fire, becoming thick and lush. The low-severity fires burn very little of the surface detritus [18]. Flattened oatgrass basal buds and dormant seeds probably survive low-severity fire. 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: Tussock graminoid Ground residual colonizer (on-site, initial community) Secondary colonizer - off-site seed


SPECIES: Danthonia compressa
IMMEDIATE FIRE EFFECT ON PLANT: Fire probably kills the culms and leaves of flattened oatgrass. PLANT RESPONSE TO FIRE: Dormant seeds in the soil or litter germinate after fire. Flattened oatgrass seedlings began growing 1 week after a spring fire on Gregory Bald in the Great Smoky Mountains National Park [18]. Poverty grass, a close relative of flattened oatgrass, regenerated from a seedbank after fire on an upland site in Michigan [22]. FIRE MANAGEMENT CONSIDERATIONS: Prescribed fire is used to maintain grassy balds in the southern Appalachian Mountains. Woody species are invading many grassy balds because of fire suppression and decreased grazing [18]. Prescribed burning was as effective as mowing in preventing woody species establishment in Big Meadows, Shenandoah National Park, Virginia. Biomass in the area prescribed burned in April was equal to the unburned control by the end of the summer [7]. Grassy balds respond well to fall fires. The fuel is less compact and favorable weather conditions last longer in the fall than in the spring [18].


SPECIES: Danthonia compressa
REFERENCES: 1. Barden, Lawrence S.; Woods, Frank W. 1974. Characteristics of lightning fires in southern Appalachian forests. In: Proceedings, annual Tall Timbers fire ecology conference; 1973 March 22-23; Tallahassee, FL. No. 13. Tallahassee, FL: Tall Timbers Research Station: 345-361. [19012] 2. Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals, reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's associations for the eleven western states. Tech. Note 301. Denver, CO: U.S. Department of the Interior, Bureau of Land Management. 169 p. [434] 3. Thompson, Frank R.; Lewid, Stephen J.; Green, Janet; Ewert, David. 1993. Status of neotropical migrant landbirds in the Midwest: identifying species of management concern. In: Finch, Deborah M.; Stangel, Peter W., eds. Status and management of neotropical migratory birds: Proceedings; 1992 September 21-25; Estes Park, CO. Gen. Tech. Rep. RM-229. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 145-158. [21273] 4. Blomquist, H. L. 1948. The grasses of North Carolina. Durham, NC: Duke University Press. 276 p. [23351] 5. Brown, Dalton Milford. 1941. Vegetation of Roan Mountain: a phytosociological and successional study. Ecological Monographs. 11: 61-97. [23349] 6. Clay, Keith. 1983. Variation in the degree of cleistogamy within and among species of the grass Danthonia. American Journal of Botany. 70(6): 835-843. [234] 7. Cocking, W. D.; Baxter, E. E.; Lilly, S. L. 1979. Plant community responses to the use of prescribed burning as an alternative to mowing in the management of Big Meadows, Shenandoah NP. In: Linn, Robert M., ed. Proceedings, 1st conference on scientific research in the National Parks: Volume II; 1976 November 9-12; New Orleans, LA. NPS Transactions and Proceedings Series No. 5. Washington, DC: U.S. Department of the Interior, National Park Service: 1205-1207. [10545] 8. Eyre, F. H., ed. 1980. Forest cover types of the United States and Canada. Washington, DC: Society of American Foresters. 148 p. [905] 9. 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] 10. 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] 11. Gould, Frank W.; Shaw, Robert B. 1983. Grass systematics. 2d ed. College Station, TX: Texas A&M University Press. 397 p. [5667] 12. Hitchcock, A. S. 1951. Manual of the grasses of the United States. Misc. Publ. No. 200. Washington, DC: U.S. Department of Agriculture, Agricultural Research Administration. 1051 p. [2nd edition revised by Agnes Chase in two volumes. New York: Dover Publications, Inc.]. [1165] 13. Horsley, S. B. 1981. Control of herbaceous weeds in Allegheny hardwood forests with herbicides. Weed Science. 29: 655-662. [23352] 14. Horsley, S. B. 1982. Development of reproduction in Allegheny hardwood stands after herbicide clearcuts and herbicide-shelterwood cuts. Res. Note NE-308. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experimental Station. 4 p. [23353] 15. Kartesz, John T.; Kartesz, Rosemarie. 1980. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. Volume II: The biota of North America. Chapel Hill, NC: The University of North Carolina Press; in confederation with Anne H. Lindsey and C. Richie Bell, North Carolina Botanical Garden. 500 p. [6954] 16. Kuchler, A. W. 1964. Manual to accompany the map of potential vegetation of the conterminous United States. Special Publication No. 36. New York: American Geographical Society. 77 p. [1384] 17. Leithead, Horace L.; Yarlett, Lewis L.; Shiflet, Thomas N. 1971. 100 native forage grasses in 11 southern states. Agric. Handb. 389. Washington, DC: U.S. Department of Agriculture, Forest Service. 216 p. [17551] 18. Lindsay, Mary M.; Bratton, Susan Power. 1979. Grassy balds of the Great Smoky Mountains: their history and flora in relation to potential management. Environmental Management. 3(5): 417-430. [23347] 19. Mark, A. F. 1958. The ecology of the southern Appalachian grass balds. Ecological Monographs. 28(4): 293-336. [23350] 20. Radford, Albert E.; Ahles, Harry E.; Bell, C. Ritchie. 1968. Manual of the vascular flora of the Carolinas. Chapel Hill, NC: The University of North Carolina Press. 1183 p. [7606] 21. Raunkiaer, C. 1934. The life forms of plants and statistical plant geography. Oxford: Clarendon Press. 632 p. [2843] 22. Scheiner, Samuel M. 1988. The seed bank and above-ground vegetation in an upland pine-hardwood succession. Michigan Botanist. 27(4): 99-106. [12396] 23. Stickney, Peter F. 1989. Seral origin of species originating in northern Rocky Mountain forests. Unpublished draft on file at: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Fire Sciences Laboratory, Missoula, MT; RWU 4403 files. 7 p. [20090] 24. U.S. Department of Agriculture, Natural Resources Conservation Service. 2018. PLANTS Database, [Online]. U.S. Department of Agriculture, Natural Resources Conservation Service (Producer). Available: [34262] 25. U.S. Department of the Interior, National Biological Survey. [n.d.]. NP Flora [Data base]. Davis, CA: U.S. Department of the Interior, National Biological Survey. [23119] 26. Wells, B. W. 1937. Southern Appalachian grass balds. Journal of the Elisha Mitchell Scientific Society. 53(1): 1-26. [23348] 27. Whittaker, R. H. 1956. Vegetation of the Great Smoky Mountains. Ecological Monographs. 26(1): 1-79. [11108]

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