GENERA OF GRASSES OF THE UNITED STATES. 145 



(Vasey) Hitchc. (Muhlenbergia emersleyi Yasey, M. vaseyana 

 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. MUHLENBEBGIA 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. Bar. Amer. 1 : 40. 1803. ' Two species are described, 

 D. urixtomun, which is Brachyelytrum erectum, and D. minutiflorum, which is 

 MuMenbergfa 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 DC. (Muhlenbergia expanse (DC.) Trin.). 



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 

 V. comata Thurb., the only species described. This is Muhlenbergia andina 

 (Nutt.) Hitchc. (Calamag'rostis andina Nutt). 



often tinged with purple ; glumes about as long as the lemma, papery, acutish, 

 scabrous ; lemma narrowed and scabrous abovo, 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, 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 



