37 



14. S. setigera, Presl. New Mexico to California. 



15. 8.? Sibirica, Lam,. Rocky Mountains, bat doubtful. 



16. S. Scribneri, Vasey. New Mexico. 



17. S. spartea, Trin. Prairies and plains, Illinois to California. 



18. S. speciosa, Trin. Arizona and California. 



19. S. Stillmanii, Boland. California. 



20. S. stricta, Vasey. California, Nevada to Oregon. 



21. S. tenuissima, Trin. New Mexico and Arizona. 



22. S. viridula, Trin. Rocky Mountains. 



S. viridula, var. pubescens, Vasey. Rocky Mountains. 

 S. viridula, var. minor, Vasey. Rocky Mountains. 



Oeyzopsis, Mich. 



This genus differs from Stipa chiefly in having a shorter, ovate or 

 oblong flower, with the callus at the base shorter and broader, and 

 in having usually a very short and deciduous awn to the flowering 

 glume. 



1. O. asperifolia, Michx. Northern States to Colorado. 



2. O. Canadensis, Torr. Northern States to Colorado. 



3. O. cuspidata, Benth. (Eriocoma, JVutt.) Rocky Mountains. 

 This grass has a wide distribution, not only on the Sierras of 



California, but northward to British America, and eastward through 

 all the interior region of Utah, Nevada, New Mexico, Texas, Colo- 

 rado, and Nebraska to the Missouri River. It is a perennial, grow- 

 ing in dense tufts, whence its common name of bunch grass. The 

 culms are 1 to 2 feet high, with about three narrow, convolute 

 leaves, the upper one having a long, inflated sheath which incloses 

 the base of the panicle. The radical leaves are narrow, rigid, and 

 as long as or longer than the culm. The panicle is about 6 inches 

 long, very loose, spreading, and flexuous. The branches are in 

 pairs, slender, rather distant, and are subdivided mostly in pairs. 

 The spikelets are at the ends of the capillary branches, each one 

 flowered. The outer glumes are three to four lines long, inflated 

 and widened below, gradually drawn to a sharp-pointed apex, thin 

 and colorless except the three or five green nerves, and slightly 

 hairy. The glumes inclose an ovate flower, which is covered ex- 

 ternally with a profusion of white, silky hairs, and tipped with a 

 short awn, which falls off at maturity. This apparent flower is the 

 flowering glume, of a hard, coriaceous texture, and incloses a similar 



