474 



MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



a minutely scabrous, slender, some- 

 what twisted beak about half the 

 total length of the lemma; awns equal, 

 divergent or horizontally spreading, 

 1.5 to 2.5 cm. long. % (A. reuer- 

 choni Vasey.) — Dry or rocky hills 

 and plains, Texas to Utah, Nevada, 

 and southern California, south to 

 Puebla, Mexico. 



Figure 693. — Aristidaglauca, XI. (Reverchon 1237 

 Tex.) 



23. Aristida purpurea Nutt. Pur- 

 ple three-awx. (Fig. 694.) Peren- 

 nial, often in large tufts; culms 30 

 to 50 c'm. tall; blades usually involute 

 and less than 10 cm. long, 1 to 1.5 

 mm. wide when unrolled; panicle 

 narrow, nodding, rather lax and loose, 

 usually purplish, 10 to 20 cm. long, 

 the branches and longer pedicels 

 capillary, more or less curved or 

 flexuous; first glume 6 to 8 mm. long, 

 the second about twice as long; lem- 

 ma about 1 cm. long, the body 

 tapering to a scarcely beaked sum- 

 mit, tuberculate-scabrous in lines 

 from below the middle to the sum- 

 mit; awns nearly equal, spreading, 3 

 to 5 cm. long. 91 — Dry hills and 



plains, Arkansas and Kansas to 

 Utah and Texas to southern Cali- 

 fornia; northern Mexico. Aristida 



PURPUREA Var. LAXIFLORA MeiT. 



Panicle few-flowered, the capillary 

 branches bearing 1 or 2 spikelets. 

 % — Texas to Arizona. 



24. Aristida roemeriana Scheele. 

 (Fig. 695.) Differing from A. pur- 

 purea chiefly in the smaller spikelets; 

 first glume 4 to 5 mm. long; lemma 

 7 to 8 mm. long, the awns about 2 

 cm. long. % {A. micrantha Nash.) 

 — Texas, New Mexico, and northern 

 Mexico. 



25. Aristida wrightii Nash. (Fig. 

 696.) Perennial; culms tufted, erect, 

 30 to 60 cm. tall; sheaths villous at 

 the throat and with a more or less 

 hispid or villous line across the collar; 

 blades involute, curved or flexuous; 

 panicle erect, narrow, 15 to 20 cm. 

 long; first glume 6 to 7 mm. long, the 

 second about twice as long; lemma 10 

 to 12 mm. long; awns nearly equal, 

 about 2 cm. long, divergent. % — 

 Dry plains and hills, Oklahoma, 

 Texas, Colorado, and Utah to south- 

 ern California and central Mexico. 



26. Aristida longiseta Steud. Red 

 three-awx. (Fig. 697.) Perennial, 

 often in large bunches; culms 20 to 30 

 cm. tall; blades involute, curved or 

 flexuous, usually less than 15 cm. 

 long; panicle narrow, erect but not 

 stiff, few-flowered, the axis only a 

 few cm. long, the branches ascending 

 or appressed, or the lower more or 

 less curved or flexuous; first glume 8 

 to 10 mm. long, the second about 

 twice as long; lemma terete, 12 to 15 

 mm. long, only slightly narrowed 

 above, glabrous or the upper part 

 scaberulous but scarcely tuberculate- 

 scabrous in lines as in .4. purpurea: 

 awns about equal, divergent, 6 to 8 

 cm. long. % — Plains and foothills, 

 North Dakota and Iowa to Montana 

 and British Columbia, south to 

 Texas, Arizona, and northern Mexico. 

 Aristida loxgiseta var. rariflora 

 Hitchc. Differing in the few-flowered 

 panicles with capillary flexuous 

 branches bearing 1 or 2 spikelets. 



