Plants annual or perennial; usually rhizomatous, often cespitose, sometimes mat-forming, rarely stoloniferous. Culms 2-300 cm, erect, geniculate, or decumbent, usually herbaceous, sometimes becoming woody. Sheaths open; ligules membranous or hyaline (rarely firm or coriaceous), acuminate to truncate, sometimes minutely ciliolate, sometimes with lateral lobes longer than the central portion; blades narrow, flat, folded, or involute, sometimes arcuate. Inflorescences terminal, sometimes also axillary, open to contracted or spikelike panicles; disarticulation usually above the glumes, occasionally below the pedicels. Spikelets with 1(2-3) florets. Glumes usually (0)1(2-3)-veined, apices entire, erose, or toothed, truncate to acuminate, sometimes mucronate or awned; lower glumes sometimes rudimentary or absent, occasionally bifid; upper glumes shorter than to longer than the florets; calluses poorly developed, glabrous or with hairs; lemmas glabrous, scabrous, or with short hairs, 3-veined (occasionally appearing 5-veined), apices awned, mucronate, or unawned; awns, if present, straight, flexuous, sinuous, or curled, sometimes borne between 2 minute teeth; paleas shorter than or equal to the lemmas, 2-veined; anthers (1-2)3, purple, orange, yellow, or olivaceous. Caryopses elongate, fusiform or elliptic, slightly dorsally compressed. Cleistogamous panicles sometimes present in the axils of the lower cauline leaves, enclosed by a tightly rolled, somewhat indurate sheath. x = 10. Named for Gotthilf Henry Ernest Muhlenberg (1753-1815), a Lutheran minister and pioneer botanist of Pennsylvania.

Muhlenbergia is primarily a genus of the Western Hemisphere. It has approximately 155 species. Sixty-nine of the 70 species treated here are native to the Flora region. The other species, M. diversiglumis, is included because it was recently reported from Texas, but no specimens supporting the report have been found. It may be based on a misidentification. Within the Flora region, Muhlenbergia is represented best in the southwestern United States. Muhlenbergia montana is an important range grass in the southwestern United States and northern Mexico.

In the key and descriptions, puberulent refers to having hairs so small that they can only be seen with a 10 hand lens.

SELECTED REFERENCES Douglas, G.W., D. Meldinger, and J. Pojar. 2002. Illustrated Flora of British Columbia, vol. 8. British Columbia Ministry of Sustainable Resource Management and British Columbia Ministry of Forests, Victoria, British Columbia, Canada. 457 pp.; Gustafson, D.J. and P.M. Peterson. 2007. Re-examination of Muhlenbergia capillaris, M. expansa, and M. sericea (Poaceae: Muhlenbergiinae). Journal of the Botanical Research institute of Texas 1: 85-89; Herrera-Arrieta, Y.1998. A revision of the Muhlenbergia montana (Nutt.) Hitchc. complex (Poaceae: Chloridoideae). Brittonia 50:23-50; Hitchcock, A.S. 1935b. Muhlenbergia Schreb. Pp. 431-476 in M.A. Howe, H.A. Gleason, and J.H. Barnhart (eds.). North American Flora, vol. 17, part 6. New York Botanical Garden, New York, New York, U.S.A. 64 pp.; Hitchcock, A.S.1951 [title page 1950]. Manual of the Grasses of the United States, ed. 2, rev. A. Chase. U.S.D.A. Miscellaneous Publication No. 200. U.S. Government Printing Office, Washington, D.C., U.S.A. 1051 pp.; Kartesz, J. and C.A. Meacham. 1999. Synthesis of the North American Flora, Version 1.0 (CD-ROM). North Carolina Botanical Garden, Chapel Hill, North Carolina, U.S.A.; Kearney, T.H. and R.H. Peebles. 1951. Arizona Flora. University of California Press, Berkeley and Los Angeles, California, U.S.A. 1032 pp.; McGregor, R.L., T.M. Barkley, R.E. Brooks, and E.K. Schofield. 1986. Flora of the Great Plains. Contribution No. 84-135-B, Division of Biology, Kansas Agricultural Experiment Station, Kansas State University. Contribution No. 1254, Department of Botany, North Dakota Agricultural Experiment Station, North Dakota State University. University Press of Kansas, Lawrence, Kansas, U.S.A. 1392 pp.; Morden, C.W. and S.L. Hatch. 1984. Cleistogamy in Muhlenbergia cuspidata (Poaceae). Sida 10:254-255; Morden, C.W. and S.L. Hatch. 1996. Morphological variation and synopsis of the Muhlenbergia repens complex (Poaceae). Sida 17:349-365; Peterson, P.M. 2000. Systematics of the Muhlenbergiinae (Chloridoideae: Eragrostideae). Pp. 195-212 in S.W.L. Jacobs and J. Everett (eds.). Grasses: Systematics and Evolution. International Symposium on Grass Systematics and Evolution (3rd:1998). CSIRO Publishing, Collingwood, Victoria, Australia. 408 pp.; Peterson, P.M. and C.R. Annable.1991. Systematics of the annual species of Muhlenbergia (Poaceae-Eragrostideae). Syst. Bot. Monogr. 31:1-109; Peterson, P.M.and Y. Herrera-Arrieta. 2001. A leaf blade anatomical survey of Muhlenbergia (Poaceae: Muhlenbergiinae). Sida 19:469-506; Soderstrom, T.R. 1967. Taxonomic study of subgenus Podosemum and section Epicampes of Muhlenbergia (Gramineae). Contr. U.S. Natl. Herb. 34:75-189; Swallen, J.R.1932. Five new grasses from Texas. Amer. J. Bot. 19:436-442; Welsh, S.L., N.D. Atwood, S. Goodrich, and L.C. Higgins (eds.). 1993. A Utah Flora, ed. 2, revised. Monte L. Bean Life Science Museum, Brigham Young University, Provo, Utah, U.S.A. 986 pp.

Plants annual or perennial; synoecious; tufted, cespitose, or sprawling. Culms 2-30 cm. Sheaths open; ligules membranous; blades flat. Inflorescences terminal, racemelike, 1-sided panicles, usually exceeding the upper leaves; branches 0.4-0.8 mm, not appressed to the rachis, with 3 spikelets, bases sharply curved, strigose, axes not extending beyond the distal spikelets; disarticulation at the base of the branches. Spikelets with 1 floret; lateral spikelets pedicellate, staminate or sterile, varying from rudimentary to as large as the central spikelet; central spikelets sessile or pedicellate, laterally compressed, bisexual. Glumes exceeded by the florets, cuneate, truncate to bilobed, 1-veined, awned from the midveins, sometimes also from the lateral lobes; lemmas 3-veined, central veins and sometimes the lateral veins extended into awns, central awns always the longest; paleas almost as long as the lemmas, 2-keeled, 2-awned; lodicules 2; anthers 3; styles 2. Caryopses about twice as large as the embryos; hila punctate. x = 10. Name from the Greek aix, goat, and pogon, beard, alluding to the fascicles of the awns of the spikelets.

Aegopogon is an American genus of four species that extends from the southwestern United States to Peru, Bolivia, and northern Argentina. One species is native in the Flora region.

SELECTED REFERENCE Beetle, A.A.1948. The genus Aegopogon Humbold. & Bonpl. Univ. Wyoming Publ. 13:17-23.