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



Figure 421— Distribution of 

 Triodia albescens. 



30 cm long; spikelets short-pediceled, 4- to 6-flowered, about 



5 mm long, the florets closely imbricate; glumes as long as the 

 spikelet, or nearly so, the apex spreading, the keel 

 glandular- viscid toward maturity; lemmas about 3 

 mm long, obtuse, the keel and margins pilose on the 

 lower half to two-thirds, the midnerve excurrent as a 

 minute awn; palea about as long as the lemma, short- 

 ciliate on the sharp keels, not strongly bowed 

 out. % (Tricuspis striata A. Gray; Tridens strictus 

 Nash.) — Low moist ground and 

 low woods, Tennessee, Missouri, 

 and Kansas to Alabama and 

 Texas (fig. 419). 



12. Triodia albescens Vasey. 

 White triodia. (Fig. 420.) 

 Culms erect, tufted, 30 to 80 cm 

 tall; blades flat to loosely invo- 

 lute, elongate, 2 to 4 mm wide, 



tapering to a fine point; panicle narrow, rather dense, 

 greenish to nearly white, 10 to 20 cm long; spikelets 

 short-pediceled, 8- to 12-flowered, 5 to 7 mm long, the 

 florets closely imbricate ; glumes a little longer than the 

 first lemma, subacute; lemmas 3 

 mm long, obscurely pubescent on 

 the callus, otherwise glabrous, 



obtuse, the midnerve minutely or not at all ex- 

 current; 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 (fig. 421). 



13. Triodia mutica (Torr.) Scribn. Slim 



triodia. (Fig. 422.) 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 6- to 8- 



flowered, about 1 cm long, pale to purplish, nearly 

 terete ; glumes scaberu- 

 lous, about as long as the 

 lower florets ; lemmas 

 about 5 mm long, densely 

 pilose on the lower half of 

 the nerves and on the cal- 



Figttre 420.— Tri- 

 odia albescens. 

 Panicle, X 1; 

 two views of 

 floret, X 5. 

 (Ball 1652, 

 Tex.1 



FlGUBE 423.— Distribution of 

 Triodia mutica. 



lus, obtuse, entire or mi- 



Figtjre 422.— Triodia mutica. 

 Panicle, X 1; two views of 

 floret, X 5. (Chase 5902, 

 Tex.) 



nutely notched, the mid- 

 nerve not exserted; palea 

 half or two-thirds as long as the lemma, densely pilose on the keels 

 and puberulent on the back. % (Tridens muticus Nash.) — Plains 

 and rocky slopes, Arkansas and Texas to southeastern California, 

 north to Nevada, Utah, and Colorado (fig. 423). 



