MANUAL OF THE GRASSES OF THE UNITED STATES 387 



51. Muhlenbergia longiligula Hitchc. (Fig. 807.) Culms erect, 

 about 1 m tall, the base hard, wiry, cylindric, the lower sheaths 

 expanded: ligule (or auricle of sheath) firm, usually about 1 cm long; 

 blades as much as 50 cm long, 2 to 5 mm wide, flat to subinvolute, 

 very scabrous, usuallv drying involute; panicle narrow, somewhat 



Figure S00.— Muhlenbergia rigida. 



Panicle and lieule. X 1; glumes and floret. X 10. (Metcalfe 1447, 

 X.Mex.) 



loose, erect, 20 to 40 cm long, the branches ascending or appressed; 

 spikelets 2 to 3 mm long; glumes subequal, acutish, usually glabrous; 

 lemma usually about as long as the glumes, glabrous, awnless, rarely 

 with a minute awn. % (Epicampes ligulata Seribn., not Muhlen- 

 bergia ligulata Seribn. and Merr.) — Canyons and rocky slopes, west- 

 ern New Mexico, Arizona, southern Nevada, and northern Mexico. 



52. Muhlenbergia lindheimeri Hitchc. 

 (Fig. 808.) Culms erect, 1 to 1.5 m tall, the 

 numerous overlapping lower sheaths keeled; 

 ligule rather thin, elongate, mostly hidden 

 in the folded base of the blade; blades elon- 

 gate, firm, flat or usually folded, about 3 mm 

 wide, scaberulous or glabrous; panicle nar- 

 row, pale, somewhat loose, erect, 20 to 40 cm 

 long, the branches ascending or appressed; 

 spikelets 2.5 to 3 mm long; glumes acute to 

 rather obtuse, scabrous-puberulent ; lemma 

 a little shorter to a little longer than the 

 glumes, 3-nerved, glabrous or obscurely pu- 

 bescent, awnless or rarely with an awn as 

 much as 3 mm long. % — Rockv slopes, 

 Texas. 



53. Muhlenbergia involuta Swallen. 

 (Fig. 809.) Culms erect, densely tufted, 60 

 to 135 cm tall; sheaths compressed-keeled; 



*. scabrous; ligule about 10 mm long; blades 

 floret, x P m icl ?M*tca^^ involute, wiry, scabrous; panicle 



erect, narrow, 30 to 40 cm long, the sub- 

 capillary branches ascending or appressed, naked toward the base, the 

 lower as much as 20 cm long; spikelets 3 to 4.5 mm long; glumes 

 acute or somewhat erose, scabrous, 2 to 2.5 mm long; lemma densely 

 pubescent on the margin toward the very base, the minutely toothed 

 apex awned from just below the teeth, the awn slender, 1.5 to 2 mm 

 long. 01 — Canyons and ravines, southern Texas. 



