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



culm, commonly purple, the capillary branches finally spreading, the 

 pedicels mostly as long as the spikelets or longer ; spikelets about 3 mm 

 long, the glumes, including the awn-tip, about two-thirds as long; 

 lemma nearly glabrous, tapering into a delicate awn about 3 mm 

 long. 9[ (M. gracillima Torr.) Plains, mesas, and dry hills, 

 western Kansas and Colorado to Texas and Arizona (fig. 795). 



43. Muhlenbergia arenicola Buckl. (Fig. 796.) Resembling M. 

 torreyi; culms taller, mostly 30 to 50 cm tall; blades usually straight 

 and on the average longer; panicle larger, mostly pale, the branches 

 and pedicels appressed; spikelets slightly longer, the lemma scabrous. 



FIGURE 787. Muhlenbergia arsenei. Plant, X 1; 

 glumes and floret, X 10. (Type.) 



FIGURE 788. Muhlenbergia monticola. Plant, X 

 1; glumes and floret, X 10. (Nealley 399, Tex.) 



91 Sandy plains and mesas, western Kansas to Arizona, south to 

 northern Mexico (fig. 797). 



44. Muhlenbergia setifolia Vasey. (Fig. 798.) Perennial, tufted; 

 culms erect, hard, wiry, 50 to 80 cm tall; sheaths with erect auricles, 

 2 to 10 mm long; blades in volute, fine, scarcely 0.5 mm thick, very 

 scabrous, flexuous, as much as 20 cm long; panicle narrow, open, 10 

 to 15 cm long, the capillary branches ascending, flexuous; spikelets, 

 excluding awns, about 5 mm long, the glumes one-third to half as long, 

 obtuse to subacute, often with a short delicate awn; lemma hairy 

 on the callus, otherwise smooth, tapering into a flexuous awn 1.5 to 

 2 cm long. 91 Rocky hills, western Texas to Arizona and north- 

 ern Mexico. 



45. Muhlenbergia dubia Fourn. PINE MUHLY. (Fig. 799.) Per- 

 ennial, closely tufted; culms erect, hard and wiry at base, 30 to 100 



