146 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. 
Chaboissaea 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.) 
Eydb. (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. SI. — 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- 
pauperate 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. Muhlenbergia mexicana (L.) Trin. and its 
allies have branching stems and numerous panicles. The glumes are 
