216 MISC. PUBLICATION 200, U. 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 strida 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 

 figure 420.- Trt- short-pediceled, 8- to 12-flowered, 5 to 7 mm long, the 

 Pan ic ieJ 6e ' 5 x n i'; florets closely imbricate ; glumes a little longer than the 

 two viWs of fi rs t lemma, subacute; lemmas 3 

 (Baii'i652| mm long, obscurely pubescent on 

 Tex-) the callus, otherwise glabrous, 



obtuse, the midnerve minutely or not at all ex- 

 current; palea a little shorter than the lemma, 

 bowed out below. % (Rhombolytrum 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 

 subin volute, 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- 

 lus, obtuse, entire or mi- 

 Figure 423.— Distribution of nutelv notched, the mid- 



Triodia mutica. J ' ■, ■, 



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). 



Figure 422.— Triodia mutica. 

 Panicle, X 1; two views of 

 floret, X 5. (Chase 5902, 

 Tex.) 



