146 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. 



Chaboissnea Fourn., Mex. PI. 2: 112. 1886. A single species, C. ligulata, is 

 included. This is Muhlenbergia ligulata (Fourn.) Scribn. and Merr. 



Muhlenbergia is a somewhat artificial genus, including species of 

 very diverse habit. It differs from Sporobolus in the 3-nerved awned 

 or mucronate lemma, and from Agrostis in the firmer lemma, usually 

 longer than the glumes. One group, including M. squarrosa (Trin.) 

 Rydb. (fig. 81), M. repens (Presl) Hitchc., and their allies, has been 

 usually referred to Sporobolus. The species of this group are in- 

 cluded in Muhlenbergia because of the 3-nerved mucronate or awned 

 lemmas, but they form a distinct section or possibly a distinct genus. 



FIG. 81. Muhlenbergia, squarrosa. Plant, X \ ; spikelet and floret, X 5. 



In M. repens the lateral nerves of the lemma are commonly obsolete, 

 and the apex is sometimes scarcely mucronate. 



Of the species found in the United States two are annuals, M. de- 

 pauperata Scribn., with acuminate or awned glumes, and M. micro- 

 sperma (DC.) Kunth, with obtuse glumes, both growing in the ex- 

 treme Southwest. The latter species produces cleistogenes in the axils 

 of the lower sheaths. Muhleiibergia mexicana (L.) Trin. and its 

 allies have branching stems and numerous panicles. The glumes are 



