412 GRAMINE^E. (GRASS FAMILY. ) 



8. S. asperifolius, Thurb. Stems 6 to 15 inches long, branched, de- 

 cumbent at base and forming broad matted tufts : leaves flat, scabrous, espe- 

 cially on the margins and upper surface: panicle included at base, 3 to 5 inches 

 long, pyramidal or ovoid in outline, the scabrous rays solitary or in pairs, bearing 

 3 to 4-flowered capillary branches: spikelets less than a line long: outer glumes 

 minutely scabrous. — Bot. Calif, ii. 269. Vilfa asperifolia, N. & M. Prom 

 .Nebraska to Texas, Mexico, California, and Oregon. 



19. AGROSTIS, Linn. Bent Grass. 



Mostly perennials, with slender low culms which form dense tufts. Ours 

 are strictly one-flowered. 



* Palet present. 



1. A. alba, L. Stems varying from a few inches to 2 feet high, sometimes 

 decumbent at base: leaves flat, short, smooth or roughened ; ligule short and trun- 

 cate or long and acute : panicle slender, usually spreading whten in flower and more 

 or less contracted afterwards, green, purplish, or brownish : flowering glume 

 very thin, 3 or 5-nerved, rarely with a short awn : palet \ to i the length of the 

 flowering glume. — Includes A vulgaris, With. Found in all cultivated regions. 

 A. vulgaris differs from A. alba principally in the ligule of the former being 

 short and truncate and that of the latter elongated and acute, hence they are 

 both here included under the older name of A. alba. The form vulgaris is 

 often called " Red-top." 



2. A. exarata, Trin. Stem erect, 1 or 2 feet high or more, at length 

 naked for some distance below the panicle : leaves mostly erect and flat, 

 the radical 2 to 4 and those of the stem 6 inches long or more, roughish or very 

 rough ; ligule obtuse, more or less decurrent : panicle erect, rather narrow, dense 

 to very dense and crowded, pale greenish, rarely tinged with purple : flowering 

 glume £ to \ shorter than the outer glume, 4 to 5-nerved, and marked on the 

 back by a longitudinal furrow, sometimes awned above the middle : palet usu- 

 ally shorter than the ovary, sometimes longer. — Common west of the Mississippi 

 and exceedingly variable, so much so that many forms described as distinct 

 species must be included under it. 



* * Palet entirely wanting or very minute. 

 -»- Spikelets awnless or short-aicned. 



3. A. perennans, Tuckm. Stems slender, 1 to 2 feet high : leaves flat: 

 panicle at length diffusely spreading, pale green ; the branches short, divided and 

 flower-bearing from or below the middle. — In Montana and Wyoming, and very 

 common eastward. Called " Thin Grass." 



4. A. scabra, Willd. Stems very slender, 1 to 2 feet high : leaves short 

 and narrow, the lower soon involute: panicle very loose and divergent, purplish, 

 the long capillary branches flower-bearing at and near the apex. — Common 

 throughout the whole continent. Called " Hair Grass " or " Fly-away Grass." 



+_ h_ Spikelets awned. 



5. A. canina, L. Stems \ to 2 feet high : root-leaves involute bristle- 

 form, those of the stem flat and broader : panicle 2 to 6 inches long, spread- 

 ing, the unequal rays in clusters of five below, in pairs or solitary above, 

 roughened, branching above the middle : spikelets purple or brownish : 



