892 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
long; lemma about 5 mm, long, loosely hairy, with long, white hairs, the four teeth 
fringed or frayed into minute, hair-like teeth, with 3 scabrous awns, 1 to 1.5 mm. 
long, palet 4-notched, two-nerved with two scabrous awns, hairy on the edges and 
laciniate at apex like the lemma, 4mm. long; rudiment consisting of two rudimentary 
florets, the lower composed of rudimentary scale-like glumes and three long, scabrous 
awns (about 3 mm. long), subtended by a tuft of long, straight, white hairs, all borne 
upon a naked stipe 1 mm. long; second rudiment consisting of scale-like glumes 
upon a naked, short stipe; caryopsis ovate to obovate, about 1.26 mm. long, the 
scutellum covering nearly the entire ventral surface. (Piare 75, A, B. Ficures 
45, 46.) 
There are large areas in southern Arizona and neighboring regions where this is 
the most important grass of the stock ranges. It inhabits the upper mesas and the 
Fic. 45.—Bouteloua rothrockii. a, Spikelet; b,c, lemma and palet of first floret; d, e, rudimentary second 
and third florets; f, two views and cross-section of caryopsis. a, Scale 7.5; b-f, scale 20. a-e, From type 
specimen; /, from Griffiths 7185, 
gentle, brushless slopes of the foothills during the summer rainy season, July to 
September, often to the exclusion of all other species. It is a very characteristic 
species, and although often appearing to intergrade with B. barbata it is very distinct 
and easily distinguished in the field. There are many specimens, however, which 
are very difficult to separate from B. barbata on the herbarium sheet. When the 
EXPLANATION OF PLATE 75.—A. An isolated tuft of Bouteloua rothrockii on desert east of Tucson, 
Arizona. B. A large native crop of Bowtelowa rothrockii in southern Arizona. This area had not been 
pastured for five years. 
