HITCHCOCK—-MEXICAN GRASSES. 
One glume and often both of all spikelets awned. 
Panicle open, the primary branches spread- 
ing; lemma ciliate 
Panicle narrow, the branches appressed. 
Glumes narrow, firm, the first usually 
Glumes broad at base, membranous, 
entire... -. cence cece eee eee ee eee 
Glumes not awned, often acute or acuminate. 
Second glume broad, 3-toothed; awn flexuous... 
Second glume entire; awn straight. 
Lemma, 2-lobed; glumes villous..........-- 
Lemma entire; glumes not villous. 
Second glume 2 to 3 mm. long. 
Leaves clustered at the base of the 
nearly simple culms, the 
sheaths inflated..........---- 
Leaves not clustered nor with in- 
flated sheaths; culms ‘reely 
branching.......-.-..------ 
Second glume not over 1 mm. long. 
Glumes acute or mucronate; body 
of lemma 1.5 mm: long...--. 
Glumes obtuse; body of lemma 2 to 
3 mm. long. 
Pedicels capillary, flexuous or 
recurved 
Pedicels short, relatively stout, 
often reflexed but not 
curved or flexuous 
Plants perennial. 
Plants producing creeping rhizomes; blades short; stems 
usually low, often decumbent; awn usually short. 
Callus hairs conspicuous; glumes awned, nearly as 
long as the short-awned or long-awned lemma; 
blades flat........--.------------------eeeeee 
Callus hairs inconspicuous. 
Main culms tall, woody, conspicuously larger 
than the numerous slender branches. .... - 
Main culms slender. 
Glumes very short, the second 0.5 mm. or 
less long, the first nearly obsolete; 
culms long and straggling......--.---- 
Glumes longer, subequal. 
Panicle narrow or reduced, the main 
branches short, appressed. 
Ligule 2 to 3 mm. long; blades flat, 
. thin; spikelets scarcely 2 mm. 
Ligule short; blades more or less 
involute, firm; spikeletsabout 
Panicle open, at least the main branches 
spreading or ascending, slender. 
81544°—13——8 
14, 
15. 
. 10. 
12..- 
13. 
17, 
16. 
20. 
18. 
287 
. M. ciliata. 
M. schaffneri. 
. MM. tenella. 
M. peruviana. 
M. biloba. 
. M. pulcherrima. 
M. quitensis. 
. M. nebulosa. 
M., implicata. 
M. microsperma. 
M. lemmoni. 
. M. dumosa. 
M. schreberi. 
M. repens. 
M. squarrosa, 
