GRAMINEAE (GRASS FAMILY) 57 



29. AGROSTIS L. BENT GRASS. HERD'S GRA.SS 



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, inclosed in the lemma. 



Rachilla prolonged behind the palet 1. A. Thurberiana. 



Rachilla not prolonged 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. asperifolia. 



Plant 10-20 cm. high 6. A. Rossae. 



Panicle diffusely spreading. 

 Lemma awnless. 



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



Plant 10-20 cm. high 8. A. idahoensig. 



Lemma awned . . . . . . . . . 9. A. melaleuca. 



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

 1905. Culms tufted, slender, 20^10 cm. high, somewhat decumbent at base: 

 basal leaves numerous, lax, slightly scabrous; culm leaves 2 or 3; ligule 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 1.3mm. long; callus obscurely 

 hairy. From western Wyoming to Washington. 



2. Agrostis alba L. Sp, PL (>">. 17-"):;. 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 glume. 

 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 filiform: 

 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 depressa Vasey, Bull. Torr. Bot. Club 13: 54. 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; ligule 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. Unifl. 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. 



0. 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, 



