GRASS FAMILY 53 



30. AGROSTIS L. Red-top, Bent-grass, Tickle-grass. 



Annuals or perennial, mostly tufted, Inflorescence paniculate. Spikelets 

 numerous, small, 1-flowered, articulate above the empty glumes. Empty glumes 

 2, persistent, membranous, keeled, acute, awnless. Lemma shorter, or barely 

 equalling the empty glumes, thin-hyaline, awnless or awned. Palet small, thin- 

 hyaline, or often wanting. Stamens usually 3. Styles short, distinct; stigmas 

 plumose. 



Rachilla prolonged above the palet, naked or minutely pubescent; lemma equalling 

 the empty glumes; palet nearly as long. 

 Spikelets about 3 mm. long, purple; racliilla one-third to one-half as long as the flower. 



1. A. aeouivnlvis. 

 Spikelets about 2 mm. long: rachilla less than one-third as long as the flower. 



Empty glumes dark purple, broadly lanceolate, abruptly acute or acuminate; 



inflorescence short and open; stem few-leaved. 2. A. atrata. 



Empty glumes green, only tinged with purple towards the tip, narrowly lanceolate, 

 gradually acute; inflorescence long and narrow; stem leafy. .3. A. Thurhcriana. 

 Rachilla not prolonged above the palet; lemma shorter than the empty glumes. 

 Palet evident, 2-nerved, at least one-fourth as long as the lemma. 



Empty glumes obtuse, scabrous on the back; panicle dense; branches flower- 



bearmg from the base, verticillate. 4. .4. stnlnnifera. 



Empty glumes acute or acuminate, glabrous or scabrous on the kee! only. 

 Plant erect or decumbent at the base, but not e.xtensively stoloniferous. 



Plant tall, usually over 3 dm. high; panicle large, open; spikelets over 2 



mm. long. o. .4. alba. 



Plant low, slender, 1-3 dm. high; panicle narrow; spikelets about 2 mm. 

 long or less. 

 Lemma nearly as long as the empty glumes; palet about two-thirds as 



long as the lemma; plant erect. 6. .4. humilis. 



Lemma one-third shorter than the empty glumes; palet about one-half 

 as long as the lemma; plant decumbent at the base. 



7. A. depressa. 

 Plant extensively stoloniferous; stolons with short leaves; palet one-fourth to 

 one-half as long as the lemma. 8. A. reptans. 



Palet lackmg or minute. 



Plant with creeping rootstock. 9. A. foliosa. 



Plant tufted, without creeping rootstock. 



Panicle dense and narrow; branches ascending or erect, flower-bearing to 

 near the base. 

 Plant over 3 dm. high; empty glumes 2.5-3 mm. long. 



Panicle lobed or interrupted; branches densely verticillate and flower- 

 bearing to the base; empty glumes narrowly lanceolate, gradually 

 attenuate: ligules 4-5 mm. long, lacerate; leaf-blades 6-10 mm. 

 wide. 10. .4. grandis. 



Panicle usually contiguous: branches few and some naked at the base; 

 empty glumes lanceolate, abruptly pointed; ligules 2-4 mm. long, 

 entire or toothed; leaf-blades 2-5 ram. wide. 11. A. asperifolia. 



Plant 1-2 dm. high; empty glumes 2 mm. long or less. 



Basal leaf-blades flat, 2 mm. wide; lemma two-thirds as long as the 



empty glumes, obtuse. 12. .4. Rossae. 



Basal leaf-blades 1 mm. wide or less, conduplicate; lemma tliree-fourths 

 as long as the empty glumes, acute. 13. .4. rariabilis. 



Panicle open: branches more or less spreading, or sometimes refle.xed. 

 Lemma a^vnless or with a very short awn. 



Panicle oblong-ovoid, its branches ascending. 



Plant 1-4 dm. liigh; empty glumes unequal, 1.5-2 mm. long. 



14. A. idahoensis. 

 Plant 3-6 dm. high; empty glumes equal or nearly .so, 3 mm. long. 



15. A. oregonensis. 

 Panicle triangular-ovoid or broadly conic; branches at least in age 



divaricate or even reflexed. 

 Leaf-blades filiform, 1 mm. wide or less, usually involute; the basal 



ones numerous; upper sheaths close. 16. .4. oreophila. 



Leaf-blades usually flat, 1-3 mm. wide; upper sheaths loose. 



17. A. hyemalis. 

 Lemma a\vned; awn equalling or exceeding the glume. 

 Panicle open, diffuse; branches spreading or ascending. 



Leaf-blades about 0.5 mm. wide; panicle broadly conic; branches 



very scabrous, in age spreading or reflexed. 18. A. geminata. 

 Leaf-biades 1-2 mm. wide; panicle ovoid; branches ascending. 



19. A. Bakeri. 

 Panicle narrow; branches nearly erect. 20. A. melaleuca. 



1. A. aequivalvis Trin. Tufted perennial; stems 2-6 dm. high; leaf-blades 

 erect, 4-6 cm. long, 1-2 mm. wide, somewhat scabrous; panicle open, 5-15 cm. 

 long; empty glumes equal, acuminate, scabrous on the keel towards the end; 

 lemma obtuse. Meadows: Alaska — -B.C. — Ore.; Lab. Subalp. Je-Au. 



