DESCRIPTIONS OF TRIBES AND GENERA. 135 



2-3-flowered ; inflorescence of the ? plant capitate, ses- 

 sile (recalling Cenchrus], scarcely exserted from the 

 sheath of the subtending leaf ; empty glumes two, con- 

 cave, indurated, three-lobed. 



Species one (B. dactyloides Engelm.), the renowned 

 "Buffalo grass" of the North American prairies. In 

 Texas it remains green over winter, and if it completely 

 dries up during the summer drouth it is still readily eaten 

 by cattle, and a few hours' rain is sufficient to make it 

 green again. 



195. (195) Opizia Presl. $ spikelets in several alter- 

 nating, slender spikes ; second empty glume of the ? 

 spikelet with three long awns surrounding the rest of 

 the spikelet like an involucre ; flowering glumes two- 

 lobed, sterile bracts long-awned. 



Species one (0. stolonifera Presl), in Mexico. 



TRIBE XL FESTTJCEJE. 



Inflorescence in panicles or racemes (apparently 

 spikes on account of the very short pedicels of the 

 spikelets) ; spikelets 2-oo -flowered, rarely one-flowered, 

 usually $ ; empty glumes usually shorter than the near- 

 est flowering glume ; flowering glumes awnless or with 

 from one to many awns which are usually terminal, rarely 

 dorsal, and straight (very rarely geniculate) ; palese two- 

 keeled ; embryo usually small ; starch-grains usually 

 compound. The most important meadow-grasses of the 

 temperate zones, as well as the predominating grasses of 

 high mountains in the tropics. 

 A.. Flowering glumes divided into three-to-many awn-like 



lobes, or with the awns rising from between the lobes, or 



dorsal. 



a. Flowering glumes cleft above into 9-23 awn-like 

 divisions 196. Pappophorum. 



b. Flowering glumes with 9-11 irregular, membra-- 

 naceous, awned lobes 197. Cottea. 



c. Flowering glumes with 5-9 dorsal awns. 



269. Boissiera. 



d. Flowering glumes with four membranaceous lobes, 

 between and at the sides of which arise five awns. 



198. Schmidtia. 



