GRASS FAMILY 53 



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



Annuals or perennial, mostly tufted, Inflorescence paniculate. Spikclets 

 numerous, sraall, 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 

 plvmiose. 



Racliilla prolonged above the palet. naked or minutely pubescent; lemma eijualling 



the empty glumes; palet nearly as long. 

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



1. A. acouirahis. 

 Spikelets about 2 mm. long; rachiUa le^s 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. Thurbcriana. 

 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- 

 bearing from tlie base, verticillate. . 4. ^. stolonifera. 

 Empty glumes acute or acunuiiate, glabrous or scabrous on the keel only. 

 Plant erect or decumbent at the base, biit not extensively stolouiferous. 



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



mm. Ions. .5. A. alba. 



Plant low, slender, 1-3 dm. high; jianicle 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. A. humilis. 



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

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



7. A. (lepressa. 



Plant extensivel> stolouiferous; stolons with short leaves; palet one-fourth to 

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



Palet lacking 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. liigh; empty glumes 2.5-3 mm. long. 



Panicle lobed or interrupted; branches densely veiticillate and flower- 

 bearing to the base; empty ghnnes narrowly lanceolate, gradually 

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

 wide. 10. A. grandis. 



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

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



entireor toothed; leaf-blades 2-5 mm. wide. 41. A. aspcrifolia. 



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



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



empty glumes, obtuse. 12. A. Rossae. 



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



as long as the empty glumes, acute. 13. A. variabilis. 



Panicle open; branches more or less si)reading, or sometimes reflexed. 



Lemma awnless or with a very short awn. 



Panicle oblong-ovoid, its branches ascending. 



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



14. A. iflahoensis. 

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



15. A. oregonensis. 

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



divaricate or even reflexed. 

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



ones numerous; upper sheaths close. 16. A, oreophila. 



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



17. A, hyemalis. 

 Lemma awned; awn equalling or exceeding the glume. 

 Panicle open, diffuse; branches spreading or ascendmg. 



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



very scabrous, in age spreading or reflexed. IS. 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 J 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. 



