GRASS FAMILY 29 



31. CALAMAGROSTIS Adans. Reed-grass. 



Awn of the lemma geniculate, exserted; callus-hairs usually much shorter than the glume 

 Awns of the lemma greatly exceeding the empty glumes; plant tufted; leaf-blades 

 involute. 

 Empty glumes very scabrous throughout; marcescent basal leaf-sheaths very 

 long, loose and numerous. 1. c. purpurascens 



Empty glumes nearly glabrous, except on the keels; marcescent basal leaf-sheaths 

 short and few. 2. C. Vaseyi. 



Awns of the lemma about equalling the empty glumes. 



Empty glumes sharply keeled; spikelets strongly compressed; plant stoloiiiferous . 



3. C. montanensis. 

 Empty glumes not strongly keeled; spikelets not strongly conpressed; plants 

 tufted. 

 Leaves usually involute; panicle very dense. 



Panicle very narrow, spike-like, usually red-purplish. 4. C. rubescens. 

 Panicle lance-oblong, usually pale green. .5. C. Suksdorfii. 



Leaves usually flat; panicle ovoid, open. 6. C. luiurians. 



Awn of the lemma straight or nearly so, included; callus-hairs usually equalling the 

 lemma (except in C. scopulorum and C. Cusickii). 

 Panicle open, the lower branches spreading; leaf-blades usually flat; callus-hairs 

 nearly or quite equalling the lemma. 

 Empty glumes 4-6 mm. long, narrow, sharp-acuminate; awn of the lemma at- 

 tached below the middle, exceeding the lemma. 7. C. Langsdorfii. 

 Empty glumes 2-4 mm. long; awn of the lemma aotached at or above the middle, 

 shorter than the lemma. 

 Awn attached near the middle of the lemma; spikelets usually purple. 

 Spikelets 3-4 mm. long: panicle loosely flowered. 8. C. canadensis. 

 Spikelets 2-2.5 mm. long; panicle densely flowered. 9. C. Macouniana. 

 Awn attached near the apex of the lemma; spikelets pale or white. 

 „ . , , 10. C. blanda. 

 Panicle more or less contracted. 

 Leaf-blades flat or nearly so. 



Empty glumes smooth or nearly so, except on the veins. 



Callus-hairs copious, at least two-thirds as long as the lemma; plant with 



a rootstock. II. C. Scribneri. 



Callus-hairs sparse, much shorter than the lemma. 



Plant tall, 9-12 dm. high; sheaths bearded at the summit; plant with a 



rootstock. 12. C. Cusickii. 



Plant lower, 3-8 dm. high; sheaths not bearded; plant tufted. 

 ^ , 13. C. scopulorum. 



Empty glumes verj scabrous; plant tufted. 14. C. elongala. 



Leaf-blades strongly involute. 



Panicle open. 15. C. lucida. 



Panicle dense, narrow, spike-like. 



Spikelets 2 ram. long; empty glumes tliickish, barely acute or obtusi.sh. 

 „ ., , 16. C. micrantha. 



Spikelets 3-4.5 mm. long. 



Plant scarcely cespitose; empty glumes long-acuminate. 



Leaves filiform, soft; plant 4-6 dm. lilgh, slender; empty glumes 



minutely scabrous on the veins. 17. C. neglecta. 



Leaves stiff and hard; plant 8-12 dm. high; empty glumes strongly 

 .scabrous. 18. C. inerpansa. 



Plant densely cespitose; empty glumes abruptly acute or short-acumin- 

 ate, very scabrous. 19. C. americana. 



32. CALAMOVILFA Hack. Reed-grass, Sand-gr.\ss. i. c. longifolia. 



33. DESCHAMPSIA Beauv. Hair-grass. 



Empty glumes not extending beyond the apex of the upper lemma; lower empty glume 

 1-nerved; densely cespitose tufted perennials. 

 Leaves neither stiff nor pungent. 



Awn inserted one-third to one-fifth from the base of the lemma; branches of the 

 inflorescence at last spreading or reflexed. 

 Awns long-exserted, at least half longer than the lemma. 



Empty glumes 3-4 mm. long; leaves flhform, revolute, scarcely 1 mm. 



wide; plant 2-3 dm. high. 1. D. curtifolia. 



Empty glumes 4-5 mm. long; leaves broader and often flat, 1.5-2.5 mm. 

 wide; plant 3-5 dm. high. 2. D. alpicola. 



Awns scarcely exserted beyond the lemma. 3. D. caespitosa. 



Awn inserted near the base of the lemma, slightly if at all exceeding it; branches 

 of the inflorescence ascending. 4. D. confinis. 



Leaves arcuate, strongly involute, very stiff and pimgent. 5. D. pungens. 



Empty glumes extending beyond the apex of the upper lemma. 



Spikelets usually dark purple; empty glumes lanceolate, purple, about 5 mm. long, 

 the lower 1-nerved. 6. D. atropurpurea. 



Spikelets light green; empty glumes linear-lanceolate, both 3-nerved. 

 Spikelets 3-5 mm. long; tufted perennials. 



Leaves filiform-involute; sheaths close; spikelets 3-4 mm. long. 



7. D. elongala. 

 Leaves involute but not filiform, or the stem-leaves flat; upper sheaths loose; 

 spikelets 4-5 mm. long. 8. D. ciliata. 



Spikelets 5-8 mm. long; annuals. 9. D. calycina. 



