MANUAL OF THE GRASSES OF THE UNITED STATES 



211 



mm. wide, flat or folded, mostly in 

 a short basal cluster, somewhat pilose, 

 the margins thick, white, the culm 

 blades 1 to 2 cm. long; panicle long- 

 exserted, ovoid, 1 to 2 cm. long, 

 pale or purplish, of 3 to 10 large 

 short-pediceled spikelets; spikelets 6- 

 to 12-flowered, 1 to. 1.5 cm. long, 

 compressed, glumes about two-thirds 

 as long as the lower florets; lemmas 

 about 6 mm. long, densely pilose 

 toward the base, pilose on the margin 

 toward the tip, acute, minutely 2- 

 toothed, the awn 1 to 2 mm. long; 

 palea half as long as the lemma, 

 pilose on the back and margins below. 



% ( Triodia acuminata Vasey ; Tri- 

 cuspis pilosa Nash; Erioneuron pilo- 

 sum Nash.) — Plains and rocky hills, 

 western Kansas to Nevada, south to 

 Texas, Arizona, and central Mexico. 



5. Tridens congestus (L. H. Dewey) 

 Nash. (Fig. 279.) Culms erect, tufted, 

 30 to 60 cm. tall; blades flat, 2 to 3 



Figure 278. — Tridens pilosus. Plant, X H< floret, 

 X 5. (Griffiths 6427, Tex.) 



Figure 279. — Tridens congestus. Panicle, X 1; floret, 

 X 5. (Tracy 8879, Tex.) 



mm. wide, tapering to a fine point; 

 panicle mostly dense, pale or pinkish, 

 4 to 10 cm. long, sometimes inter- 

 rupted below; spikelets rather tur- 

 gid, 6- to 12-flowered, 5 to 10 mm. 

 long; lemmas 3 to 4 mm. long, broad, 

 obtuse, short-pilose on the midnerve 

 and margin below, the apex slightly 

 notched, the awn less than 1 mm. 

 long; palea about as long as the lem- 

 ma, broad, abruptly bowed out be- 

 low. % — Sandy or dry plains, 

 southern Texas. 



6. Tridens buckleyanus (L. H. 

 Dewey) Nash. (Fig. 280.) Culms 

 erect, tufted, 30 to 60 cm. tall; 

 sheaths scaberulous, sometimes 

 sparsely pilose ; blades flat, i to 3 mm. 

 wide, tapering to a fine point; panicle 

 10 to 20 cm. long, the few branches 

 distant, ascending to spreading, as 

 much as 7 cm. long; spikelets pale to 

 dark purple, short-pediceled, ap- 

 pressed, rather few and somewhat dis- 

 tant along the simple branches, 3- to 



