No. 26. 

 MUHLENBERGIA GRACILIS Trinius. 



Rootstocks short, ascending. 



Culms tnfted, erect, 9 to 24 inches high, unbranched above the base, glabrous. 



Leaves all radical; sheaths of the outer ones short (1 to 3 inches long), loose, 

 flattened, slightly scabrous on the back, inner longer and sheathing, uppermost 

 usually reaching to, and sheathing, the inflorescence; blade 6 inches or less long, in 

 line with the sheaths, usually involute, scabrous on the back, glabrous above; 

 ligule membranaceous, about i to ^ inch long, at the base broader than the blade, 

 apex slender-acute and often lacerate, the whole shriveled when old. 



Inflorescence paniculate. Panicle sheathed or long-pedunculate, 2 to 7 inches 

 long, erect or nearly so; rachis scabrous; branches scabrous, 2 inches long or less, 

 nearly erect. 



Spikelets lanceolate, acute, 2 lines long exclusive of the awn, borne singly on 

 short pedicels. 



Glumes 3; first lanceolate, acuminate-aristate, 1-nerved, scabrous on the back, 

 about 1 line long, lead-colored below, hyaline above ; second slightly longer, sim- 

 ilar in texture, scabrous on the back, ovate-oblong, truncate, 3-nerved, nerves pro- 

 duced into aristate points; third (flowering) lanceolate, involute, 1-nerved or with 

 two additional nearly marginal nerves, scabrous on the back, ciliate on the mar- 

 gins, as long as the spikelets, straw-colored, with a lead-colored apex tapering into 

 a not twisted slender, scabrous, flexuous awn about £ inch long. 



Flower single, hermaphrodite. Palet lanceolate, slightly shorter than its 

 glume, obtuse when flattened, 2-nerved, scabrous on the back. Stamens 3 ; an- 

 thers linear, about 1 line long. Stigmas cylindrical, purple. 



Grain not seen. Palet and glume coriaceous when old. 



Plate XXVI ; a and b, spikelet, the parts spread open, and the rachilla 

 broken above the second glume; c, second glume; d, first glume ;■ e, same as b, 

 showing the back of the flowering glume. 



This species is common on stony ridges or hills from Mexico to Montana, and 

 a small form occurs in California. 



