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



glumes rather thin, mostly about 

 half as long as the spikelet, broad 

 at base, tapering to an awn point; 

 lemma glabrous, acuminate, awn- 

 tipped. 01 —Plains and open 

 slopes at medium altitudes, Okla- 

 homa, Colorado, Utah, New Mexico, 

 Arizona, and northern Mexico. 



26. Muhlenbergia arenacea Buckl. 

 Hitchc. (Fig. 545.) Perennial, with 

 creeping rhizomes; culms tufted from 

 the branches of the rhizomes, some- 

 times decumbent at base, 10 to 35 

 cm. tall; ligule prominent, decurrent, 



Figure 5-14. — Muhlenbergia wrightii. Plant, X 1: 

 glumes and floret, X 10. (Standley 8249, N. Mex.) 



1 to 2 mm. long, the margins usually 

 split away, forming an erect auricle 

 at each side; blades flat, wavy, mostly 

 1 to 3 cm. long, about 1 mm. wide, 

 sharp-pointed, the margins and mid- 

 nerve white and cartilaginous; pan- 

 icle diffuse, 7 to 12 cm. long, about 

 as broad, the branches and pedicels 

 capillary; spikelets about 2 mm. 

 long, rarely 2-flowered; the glumes 

 about half as long, abruptly apicu- 

 or subacute; lemma glabrous, 

 abruptly mucronate. 01 (Sporobo- 

 lus auriculatus Vasey.) — Low places 



in mesas, Texas and Colorado to 

 Arizona and Sonora. This species 

 and the next three are placed in 

 Muhlenbergia because of the 3-nerved 

 mucronate lemma. The caryopsis 

 does not fall from the lemma and 

 palea as in most species of Sporobolus, 

 nor can the pericarp be separated 

 from the grain by moistening it. 



27. Muhlenbergia asperifolia (Nees 

 and Mey.) Parodi. Scratchgrass. 

 (Fig. 546.) Perennial, pale or glau- 

 cous, with slender scaly rhizomes; 

 culms branching at base, spreading, 

 slender, compressed, 10 to 50 cm. 

 tall, the branches ascending or erect; 

 sheaths somewhat compressed-keeled, 

 usually overlapping; ligule minute, 

 erose-toothed; blades flat, crowded, 

 scabrous, mostly 2 to 5 cm. long, 

 1 to 2 mm. wide; panicle diffuse, 5 

 to 15 cm. long, about as wide, the 

 capillary scabrous branches finally 

 widely spreading, the panicle at ma- 

 turity breaking away; spikelets 1.5 

 to 2 mm. long, occasionally 2-flow- 

 ered, the pedicels capillary; glumes 

 acute, from half to nearly as long 

 as the spikelet; lemma thin, broad, 

 minutely mucronate from an obtuse 

 apex. 01 (Sporobolus asperifolius 

 Nees and Mey.) — Damp or marshy, 

 often alkaline soil, along irrigation 

 ditches and banks of streams, New 

 York, Indiana and Alberta to British 

 Columbia, south to Texas, California, 

 and Mexico; southern South America. 

 The caryopsis is frequently affected 

 by a fungus (Tilletia asperifolia Ell. 

 and Everh.) which produces a large 

 globular body. 



28. Muhlenbergia torreyana 

 (Schult.) Hitchc. (Fig. 547.) Perennial, 

 strongly compressed at base, with 

 short very scaly rhizomes; culms 

 simple, or sparingly branching at 

 base, erect, 30 to 60 cm. tall; blades 

 elongate, rather firm, flat or folded, 

 1 to 3 mm. wide; panicle oblong, 

 open, 10 to 20 cm. long, the capillary 

 branches and pedicels ascending; 

 spikelets about 2 mm. long, the 

 glumes subequal, slightly shorter; 

 lemma and palea minutely sea- 



