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



somewhat laterally compressed and 

 slightly twisted at summit, the 

 densely pubescent callus about 2 mm. 

 long; awns 2 to 2.5 cm. long, united 

 for 1 to 2 mm., the bases curved in 

 a semicircular somewhat contorted 

 bend, the upper part thus usually de- 

 flexed. O — Open sandy soil or 

 sandy woods, Illinois, Nebraska, and 

 Texas. 



2. Aristida tuberculosa Nutt. (Fig. 

 673.) Annual; culms branching, 30 to 

 60 cm. or even 1 m. tall; blades in- 

 volute, 2 to 4 mm. wide when flat; 

 panicle 10 to 20 cm. tall, the branches 

 stiffly ascending; glumes about equal, 

 gradually narrowed into an awn, 

 about 2.5 cm. long, including the 

 awn; lemma 11 to 13 mm. long, gla- 

 brous, except for the slightly sca- 

 brous summit, extending downward 

 into a densely pubescent callus 3 to 

 4 mm. long; column of awns twisted, 

 10 to 15 mm. long, the upper 2 or 3 

 mm. twisted but not united, above 

 this forming a semicircular bend, the 

 terminal straight part of the awns 

 usually deflexed, 3 to 4 cm. long. 

 O — Open sandy woods, Massa- 

 chusetts to Georgia and Mississippi 

 near the coast; around the southern 

 end of Lake Michigan and in other 

 localities in Wisconsin, Indiana, Illi- 

 nois, Iowa, and Minnesota. 



3. Aristida californica Thurb. (Fig. 

 674.) Perennial, tufted, much 

 branched at base; culms pubescent, 

 10 to 30 cm. tall; blades mostly in- 

 volute and less than 5 cm. long; pan- 

 icles numerous, mostly reduced to 

 few-flowered racemes; first glume 

 about 8 mm. long, the second about 

 12 mm. long; lemma 5 to 7 mm. long, 

 glabrous below, scaberulous toward 

 the summit, the strongly pubescent 

 callus 1.5 to 2 mm. long; column 15 

 to 20 mm. long, the awns about equal, 

 2.5 to 3.5 cm. long, spreading hori- 

 zontally, the bases arcuate and 

 slightly contorted. % — Dry sandy 

 or gravelly soil, deserts of southern 

 California, southwestern Arizona, and 



Figure 673. — Aristida tuberculosa, X 1. (V. H. Chase „„ ii „ l\T~, :„~ 



322, ind.) northern Mexico. 



Figure 672. — Aristida desmantha, X 1. (Reverchon 

 3428, Tex.) 



as much as 80 cm. tall; sheaths often 

 woolly; blades folded or involute, 2 

 to 3 mm. wide; panicle as much as 20 

 cm. long, the branches stiffly ascend- 

 ing, very scabrous, bearing 1 to few 

 spikelets; glumes slightly unequal, 

 the body about 1 cm. long, tapering 

 into an awn about half as long; lemma 

 7 to 8 mm. long, glabrous below, 



