400 



CONTRIBUTIONS FROM THE NATIONAL, HERBARIUM. 



DESCRIPTION. 



A stout, erect, mostly cespitoee perennial, with leafy base and comparatively naked 

 culms, striate, loose sheaths, small, sparingly ciliate, pubescent ligules, and slender, 

 flat, rather rigid blades, slightly pubescent beneath; panicle racemose, about 4 cm. 

 long; spikes 4 to 6, densely woolly, 1 to 1.5 cm. long, short-pedicellate from the sharp 

 angles of a zigzag rachis; spikelets consisting of one lower perfect floret and a rudiment, 

 more or less pectinate before anthesis, but this arrangement lost with the development 

 of the long, rigid awns; first glume about 3 mm. long, the second about 4 mm. long, both 



Fig. 51. — Bouteloua chondrosioidcs. a, Spikelet; b, c, lemma and palet of first floret; d, rudimentary sec- 

 ond floret; e, two views and cross section of caryopsis. a, Scale 7.5; b-e, scale 10. a-d, From type 

 specimen of B. havardii: e, from Griffiths 7266. 



densely woolly, acuminate, indistinctly keeled; lemma, about 6 mm. long, densely 

 woolly, terminating in three equal awns; palet about the same length, woolly on the 

 edges, the two nerves terminating in short awns; rudiment consisting of 3 hispid, 

 nearly equal awns, about 7 mm. long, upon a short, naked stipe 1 to 1.5 mm. long, the 

 central awn and often the lateral with glume-like wings; caryopsis oval, about 2.5 

 mm. long, 0.9 mm. wide, the scutellum covering nearly the whole ventral surface and 

 curving over the sides onto the dorsal surface. (Figure 51.) 



This species attains its maximum development in the plateau region of Mexico, 

 where there are large areas covered with it to the exclusion of nearly all else. It also 



