GENERA OF GRASSES OF THE UNITED STATES. 
145 
(Vasey) Hitchc. (Muhlenbergia emersleyi Vasey, M. vasey ana 
Scribn.), are forage grasses. A Mexican species, E. macrowa Benth., 
is of considerable economic importance, the roots being used in the 
manufacture of scrubbing brushes. 
68. Muhlenbergia Schreb. 
Spikelets 1-flowered, the rachilla disarticulating above the glumes; 
glumes usually shorter than the lemma, obtuse to acuminate or 
awned, the first sometimes small or rarely obsolete; lemma firm- 
membranaceous, 3 to 5 nerved, with a very short, usually minutely 
pilose callus, the apex acute, sometimes bidentate, extending into a 
straight or flexuous awn, or sometimes only mucronate. 
Perennial or rarely annual low or moderately tall grasses, tufted 
or rhizomatous, the culms simple or much branched, the in- 
florescence a narrow or open panicle. Species about 80, mostly in 
Mexico and the southwestern United States, a few in the eastern part 
of the Old World ; 40 species in the United States. 
Type species: Muhlenbergia schreberi Gmel. 
Muhlenbergia Gmel., Syst. Nat. 2: 171. 1791. Only one species mentioned. 
Dilepyrum Michx., Fl. Bor. Amer. 1: 40. 1803. Two species are described, 
D. aristosum, which is Brachyelytrum erectum, and D. minutiflorum, which is 
Muhlenbergia schreberi Gmel. They are equally eligible as the type. The 
second is chosen, in order to conserve the generic name Brachyelytrum. 
Podosemum Desv., Nouv. Bull. Soc. Philom. Paris 2 : 188. 1810. The type is 
Stipa capillaris Lam. (P. capillaris Desv.), the only species mentioned. 
Olomena Beauv., Ess. Agrost. 28, pi. 7, f. 10. 1812. The type is C. peruviana^ 
the only species mentioned. This is Muhlenbergia peruviana (Beauv.) Steud. 
Trichochloa Beauv., Ess. Agrost. 29, pi. 8, f. 2. 1812. The type and only 
species is T. purpurea. This has not been identified. Roemer and Schultes 
say it is Trichochloa expansa DO. {Muhlenbergia expansa (DC.) Trim). 
Tosagris Beauv., Ess. Agrost. 29, pi. 8, f. 3. 1812. The type is T. agrostidea, 
the only species mentioned. This has not been identified, but it appears to be 
a species of Muhlenbergia. 
Sericrostis Raf., Neogenyt. 4. 1825. " Type Stipa sericea Mx. or diffusa 
Walter." This is Muhlenbergia capillaris (Lam.) Trin. 
Calycodon Nutt, Journ. Acad. Phila. II. 1 : 186. 1848. The type is C. mon- 
tanum (Muhlenbergia montana Hitchc), the only species described. 
Vaseya Thurb., in Gray, Proc. Acad. Phila. 1863: 79. 1863. The type is 
T 7 . comata Thurb., the only species described. This is Muhlenbergia andina 
(Nutt.) Hitchc. (Calamagrostis andina Nutt). 
often tinged with purple ; glumes about as long as the lemma, papery, acutish, 
scabrous ; lemma narrowed and scabrous above, villous below, awnless, or occasionally 
those of a few of the spikelets with a flexuous awn about 1 cm. long. 
Type, U. S. National Herbarium no. 905799, collected in a rocky ravine, Guadeloupe 
Mountains, near Queen, N. Mex., altitude 7,000 feet, Sept. 5, 1915, by A. S. Hitchcock, 
no. 13541. 
This species is closely allied to Epicampes emersleyi j from which it differs in the awn- 
less spikelets and larger, looser, and more spreading panicles. The writer examined the 
two forms in the Guadeloupe Mountains, southern New Mexico, and concluded from these 
field observations that the awned and awnless forms represented two distinct but closely 
allied species. The delicate awns are not noticeable at a distance but the more open 
panicle was always found to be associated with the awnless spikelets. 
Other specimens in the U. S. National Herbarium. — Texas : Limpia Canyon, Nealley 
133. Chisas Mountains, Bailey 392. Guadeloupe Mountains, Bailey 739. Western Texas, 
Wright 729. New Mexico: Socorro, Plank 53. Silver City, Greene 439. Arizona: 
Patagonia, Hitchcock 3719. Chiracahua Mountains, Tourney 15a. Santa Catalina Moun- 
tains, Griffiths 7149. 
1 Syst. Veg. 2 : 384. 1817. 
97769°— 19— Bull. 772 10 
