MANUAL OF THE GRASSES OF THE UNITED STATES 



443 



twisted. % — Deserts and plains, 

 Idaho, Colorado, Nevada, and Cali- 

 fornia. 



12. Oryzopsis hymenoides (Roem. 

 and Schult.) Ricker. Indian rice- 

 grass. (Fig. 636.) Culms densely 

 tufted, 30 to 60 cm. tall; ligule about 

 6 mm. long, acute; blades slender, 

 involute, nearly as long as the culms; 

 panicle diffuse, 7 to 15 cm. long, the 

 slender branches in pairs, the branch- 

 lets dichotomous, all divaricately 

 spreading, the ultimate pedicels capil- 

 lary, flexuous; glumes about 6 to 7 

 mm. long, puberulent to glabrous, 

 rarely hirsute, papery, ovate, 3- to 

 5-nerved, abruptly pointed; lemma 

 fusiform, turgid, about 3 mm. long, 

 nearly black at maturity, densely 

 long-pilose with white hairs 3 mm. 

 long; awn about 4 mm. long, straight, 

 readily deciduous. % — Deserts 

 and plains, medium altitudes, Mani- 

 toba to British Columbia, south to 

 Texas, California, and northern Mex- 

 ico. 



Oryzopsis hymenoides var. con- 

 tracta B. L. Johnson. Panicles nar- 

 row, the branches ascending; lem- 

 mas less turgid and less copiously 

 pilose. 21 — Dry soil, Wyoming. 



Nassella chilensis (Trin. and 

 Rupr.) E. Desv. Slender tufted peren- 

 nial; blades narrow, flat or loosely in- 

 volute; panicle narrow, 3 to 5 cm. 

 long, the few branches appressed, 1 

 to 1.5 cm. long; glumes 4 mm. long, 

 awn-pointed; mature lemma flattish, 

 obovate-oblong, gibbous at apex, 

 smooth and shining, 2 mm. long; awn 

 geniculate, 1 cm. long, soon decidu- 

 ous. % (N. major (Trin. and 

 Rupr.) E. Desv.) — Ballast, Portland, 

 Oreg. Introduced from Chile. 



90. PIPTOCHAETIUM Presl 



Spikelets 1-flowered, disarticulating 

 above the glumes, the callus of the 

 floret short, acutish, usually bearded; 

 glumes about equal, broad, ovate, 

 convex on the back, thin, abruptly 

 acuminate; fruit brown or dark gray, 



Figure 635. — Oryzopsis webberi. Panicle, X 1; floret, 

 X 5. (Hillman, Nev.) 



Figure 636. — Oryzopsis hymenoides. Panicle, X 

 floret, X 5. (Mearns 2583, Wyo.) 



coriaceous, obovate, shorter than the 

 glumes, glabrous or hispid above the 

 callus, often minutely striate, some- 

 times tuberculate near the summit, 

 the lemma turgid, usually somewhat 

 compressed and keeled on the back, 

 gibbous near the summit back of the 

 awn, the edges not meeting but clasp- 

 ing the sulcus of the palea, the sum- 

 mit sometimes expanded into a crown; 

 awn deciduous or persistent, curved, 



