HITCHCOCK—MEXICAN GRASSES. 
Awns not yellow nor strongly flexuous. 
Blades short, mostly not over 10 cm. long; 
plants comparatively low. 
Lemma 2-lobed, the lobes 0.5 mm. long; 
panicle rather open............--- 38. 
Lemma entire or minutely toothed. 
Panicle open, the short branches 
spreading; glumes abruptly awned 39. 
Panicle narrow, the branches ap- 
pressed. 
Lemma 4 to 5 mm. long; glumes less 
than half as long, broad, thin; 
blades involute, mostly basal... 40. 
Lemma 2 to 3 mm. long; glumes 
more than half as long; blades 
scattered. 
Lemma conspicuously hairy; 
glumes as long as lemma, 
awned......... we aecceeeees 41, 
Lemma slightly hairy or glabrous; 
glumes shorter, acute or 
awned. 
Ligule 2 mm. long; lemma hairy 
at base, 2mm. long; glumes 
Ligule inconspicuous, 1 mm. 
long; lemmaglabrous, 3mm. 
long; glumes often awned.. 42. 
Blades elongated; plants usually tall and 
stout. 
Panicle large, diffuse; branches and 
pedicels capillary. 
Panicle about 50 cm. long; spikelets 
about 3 mm. long; plants often 2 
meters high............-.--------- 44, 
Panicle mostly less than 30 cm. long; 
spikelets about 4 mm. long; 
plants not so tall...........-.--. 45, 
Panicle not diffuse. 
Glumes shorter than the lemma. 
Glumes obtuse, erose or obscurely 
toothed; lemma villous........ 54. 
Glumes more or less acute. 
Blades flat, strongly nerved above; 
ligule 1 to 2 mm. long....... 50. 
Blades involute. 
Blades smooth; panicle green.. 56. 
Blades scabrous, at least on the 
attenuated point. 
Lemma 3 mm. long, scarcely 
nerfed; panicle green or 
tawny.......-----.-- . OT. 
Lemma 5 mm. long, strongly 
nerved; panicle purple.. 58. 
289 
M. argentea. 
M. alamosae. 
M. setifolia. 
M. polycaulis. 
3. M. monticola. 
M. pauciflora. 
M. elata. 
M., affinis. 
M. enervis. 
M. palmeri. 
M. acuminata. 
M, elongata. 
M. berlandiert, 
