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



Illinois and Kansas to North Caro- 

 lina, Alabama, and Texas. 



15. Tridens albescens (Vasey) 

 Woot. and Standi. White tridens. 

 (Fig. 289.) Culms erect, tufted, 30 to 

 80 cm. tall; blades flat to loosely in- 

 volute, elongate, 2 to 4 mm. wide, 

 tapering to a fine point; panicle nar- 

 row, rather dense, greenish to nearty 

 white, 10 to 20 cm. long; spikelets 

 short-pediceled, 8- to 12-flowered, 5 

 to 7 mm. long, the florets closely im- 

 bricate; glumes a little longer than the 

 first lemma, subacute; lemmas 3 mm. 

 long, obscurely pubescent on the cal- 

 lus, otherwise glabrous, obtuse, the 

 midnerve minutely or not at all excur- 

 rent; palea a little shorter than the 

 lemma, bowed out below. % 

 (Rhomb olytrum albescens Nash.) — 

 Plains and open woods, Kansas and 

 Colorado to Texas and New Mexico; 

 northern Mexico. 



Figure 287. — Tridens texanus. Panicle, X 1; floret, 

 X 5. (Wooton, Tex.) 



Figure 288. — Tridens stric- 

 tus. Panicle, X 1 ; two 

 views of floret, X 5. 

 (Newton, Kans.) 



current as a minute awn; palea about 

 as long as the lemma, short-ciliate on 

 the sharp keels, not strongly bowed 

 out. % (Tricuspis stricta A.Gray.) 

 — Low moist ground and low woods, 



Figure 289. — Tridens albescens. Panicle, X 1; two 

 views of floret, X 5. (Ball 1652, Tex.) 



16. Tridens muticus (Torr.) Nash. 

 Slim tridens. (Fig. 290.) Culms 

 slender, densely tufted, 30 to 50 cm. 

 tall; sheaths and blades scaberulous, 

 the sheaths usually loosely pilose, 

 more densely so at the summit ; blades 

 flat or subinvolute, 1 to 3 mm. wide, 

 sometimes sparsely pilose; panicle 

 narrow, rather dense, interrupted, the 

 branches short, appressed; spikelets 



