GEAMINEAE (GRASS FAMILY) 57 



29. AGROSTIS L. Bent Grass. Herd's Grass 



Tufted annuals or perennials with flat or bristle-like leaves and small spike- 

 lets in open, usually diffuse panicles. Spikelets 1-flowered. Glumes mem- 

 branous, keeled, acute; lemma shorter, obtuse, hyaline, sometimes bearing a 

 dorsal awn, subtending a perfect flower; palet distinct, short. Stigmas plu- 

 mose. Grain free, inclosea in the lemma. 



Rachilla prolonged behind the palet . . . , . . . 1. A. Thurberiana. 

 Kachilla not prolODged behind the palet. 

 Palet evident, 2-nerved. 



Plant usually 30 cm. or more high . . . . . . 2. A. alba. 



Plant low. 

 Erect, scarcely stoloniferous . • . . , . , 3. A. humilis. 



Low and spreading by stolons 4. A. depressa. 



Palet wanting, or a small nerveless scale. 



Panicle narrow, either strict or open but not diffuse. 



Plant 20-30 cm. high , . . 5. A. asperifoUa. 



Plant 10-20 cn^ high . . . . . . , . 6. A. Rossae. 



Panicle diffusely spreading. 

 Lemma awnless. 



Plant 20-80 cm. high 7. A. hiemalis. 



Plant 10-20 cm. high , . . 8. A. idahoensis. 



Lemma awned .• 9. A. melaleuca. 



1. Agrostis Thurberiana A. S. Hitch. U. S. Dept. Agr. Bu. PI. Ind. Bull. 68. 

 1905. Culms tufted, slender, 20— iO cm. high, somewhat decumbent at base: 

 basal leaves numerous, lax, slightly scabrous; culm leaves 2 or 3; Ugule semi- 

 circular, 6 mm. long: panicle narrow and lax, more or less drooping, 5-8 cm. 

 long, somewhat scabrous on the branches which are flower-bearing from the 

 middle: spikelets 2 mm. long: glumes equal, acute; lemma nearly as long as 

 the glumes, obtuse, faintly 5-nerved; palet about 1.3 mm. long; callus obscurely 

 hairy. — From western Wyoming to Washington. 



2. Agrostis alba L. Sp. PL 63. 1753. Perennial, variable in habit, often 

 stoloniferous, with smooth culms 3-9 dm. high, flat leaves, and erect many- 

 flowered open panicle 4-18 cm. long: leaves 5-20 cm. long, 2-6 mm. wide, 

 scabrous: spikelets 2-2.5 mm. long: glumes about equal, acute, smooth and 

 glabrous, except on the hispid or scabrous keel; lemma shorter than the 

 glumes, obtuse or acute; palet one half to three fourths as long as the glimie. 

 Redtop. — Naturalized in meadows and on wet banks. 



3. Agrostis humilis Vasey, Bull. Torr. Bot. Club 10: 21. 1883. Culms 

 slender, tufted from a perennial root, 10-40 cm. high: leaves mostly basal, 

 2-10 cm. long, 2 mm. wide, flat and thin or rarely conduplicate and fiUform: 

 panicles 2-8 cm. long, narrow, or in rank-growing plants open and loosely 

 flowered: spikelets usually purple, 1.5-2 mm. long: glumes equal, abruptly 

 pointed, smooth or nearly so; lemma as long as the glumes, awnless; palet two 

 thirds as long as the lemma. — Colorado to Montana and west to the Pa- 

 cific States. 



4. Agrostis depr?ssa Vasey, Bull. Torr. Bot. Club 13: £4. 1886. Tufted 

 and freely stoloniferous from the base: culms geniculate-decumbent, becoming 

 erect, usually 12-20 cm. high: leaves 3-5 cm. long, 1 mm. wide; the culm 

 leaves very scabrous; Ugule conspicuous, 2-3 mm. long: panicles narrow and 

 spike-like: glumes equal, acute, roughish on the keel above; lemma shorter, 

 with a minute prickle on the back below the tip; palet half as long as the 

 lemma. — Colorado to California and Washington. 



5. Agrostis asperifolia Trin. Gram. Umfl. 207. 1824. Erect tufted peren- 

 nial, 3-9 dm. high, with rough leaves and contracted panicles 6-25 cm. long: 

 leaves 3-20 cm. long, 2-8 mm. wide: panicles often interrupted or glomerate, 

 the branches erect and crowded, spikelet^bearing to the base: spikelets 2-2.5 

 mm. long: glumes scabrous, especially on the keel; lemma about three fourths 

 the length of the second glume; palet minute. A. exarata, at least in part. — 

 Throughout our range and westward. 



6. Agrostis Rossae Vasey, Contrib. U. S. Nat. Herb. 3: 76. 1892. Culms 

 rather stout, 10-20 cm. high, tufted but not stoloniferous: leaves mostly basal, 

 2-5 cm. long, 1-2 mm. wide; sheaths rather conspicuous: panicle contracted, 



