but usually interrupted; glumes 3-4 mm. long, shining, grayish, keeled, awnless; 

 lemma 2-3 mm. long, linear, grayish, glabrous but with a basal callus bearing a 

 beard of hairs 2-3 mm. long and an apical awn 4-8 mm. long; palea nearly 

 equaling lemma. 



In wet meadows, moist thickets and river beds, in the (?) Tex. Trans-Pecos 

 and N. M. (San Miguel Co.); w. U.S., e. to Wyo., Colo., N.M. and possibly Tex. 



8. Muhlenbergia racemosa (Michx.) B.S.P. Fig. 116. 



Perennial from scaly white rhizomes 1-2 mm. thick; aerial culms 3-7 dm. long, 

 0.5-2.5 mm. thick, erect, leafy, sparingly branched; ligule an erose scale 0.5-1 mm. 

 long, without auricles; blades 4-16 cm. long, 1-7 mm. broad, flat, rather stiffly 

 erect; panicles 2-14 cm. long, 4-11 mm. thick, spikelike but usually interrupted; 

 glumes 1.5-2 mm. long, lanceolate, apically with a stiff awn 2-5 mm. long; lemma 

 2.5-3.5 mm. long, short-pilose on the lower half, acuminate or the apical portion 

 awnlike; palea nearly equaling lemma. 



Moist ground, wet meadows, swamps, alluvial soil along rivers, streams and 

 irrigation ditches, in Okla. (Waterfall) and the Tex. Plains Country, rare (one 

 collection from Perryton, Ochiltree Co.), N. M. (widespread) and Ariz. (Apache 

 and Coconino cos.), Sept.-Oct.; most of U. S. w. of Miss. River. 



9. Muhlenbergia frondosa (Poir.) Fern. Wirestem muhly. 



Perennial from scaly white rhizomes 1-2 mm. thick; aerial culms 3-10 dm. 

 long, 1-2 mm. thick, leafy, profusely geniculately branched near the middle, top- 

 heavy and falling over (then often rooting at the nodes), the naked pedunculiform 

 terminal internodes only 1-4 cm. long or absent; ligule an erose scale 0.5-1 mm. 

 long, not auricled; blades 4-11 cm. long, 1.5-5 mm. broad, flat, ascending or 

 appressed; panicles 3-10 cm. long, when only 1-2 mm. thick then linear but 

 when 3-6 mm. thick tapered to both ends, loose and interrupted; glumes 2.5-3.5 

 mm. long including the awnlike tip, linear-lanceolate; lemma about 3 mm. long, 

 awnless, pubescent on the lower part; palea about 3 mm. long. 



Woods, sandbars along streams, muddy banks of streams and swales, low wet 

 soils and thickets, in Okla. [Waterfall) and n.-cen. Tex., rare (Dallas and Grayson 

 cos.) Oct.; e. Can. s. to n. Ala., Tex. and Okla. 



10. Muhlenbergia sylvatica (Torr.) Torr. 



Perennial from scaly rhizomes 1-2.5 mm. thick; aerial culms 4-10 dm. long, 

 1-3 mm. thick, leafy, moderately branched near the middle, weak and often 

 reclining, the lower nodes rooting, the internodes minutely strigose in a zone just 

 below the nodes (use lens), the terminal internodes short and not pedunculiform; 

 ligule an erose scale 0.5-1.2 mm. long; blades 6-18 cm. long, 2-7 mm. broad, 

 flat, ascending; panicles 4-10 cm. long, 3-5 mm. thick, somewhat spikelike, 

 interrupted, nodding; glumes about 2 mm. long, awnless or with an awnlike tip 

 0.1-1 mm. long; lemma about 3 mm. long, pubescent in the lower part, with 

 an awn 3-10 mm. long; palea about 3 mm. long. 



Dense woods and swampy meadows, in Okla. (Waterfall) and n.-cen. Tex. and 

 e. Edwards Plateau, rare, Aug -Sept.; s.e. Can. s. to n. Ala. and Tex. 



11. Muhlenbergia mexicana (L.) Trin. 



Resembling M. frondosa: culms erect or ascending, usually simple below, less 

 freely branching, scaberulous below the nodes; blades lax, 1-2 dm. long, mostly 

 2-4 mm. wide; panicles mostly long-exserted, narrow, the upper often 10-15 cm. 

 long, of numerous short appressed densely flowered somewhat aggregate branches; 

 spikelets 2-3 mm. long; glumes narrow, attenuate, awn-tipped, about equaling 

 the pointed or awn-tipped lemma, the lemma long-pilose below. 



249 



