POACEAE. 47 



Lower glume 3-nerved. 



Annual; glumes 5-7 mm. long. D. calycina. 



Perennial; glumes 3-4 mm. long. D. elongata. 



Deschampsia caespitosa (L.) Beauv. Silver-top. Densely tufted perennial; 

 stems 60-150 cm. high, much exceeding the numerous basal leaves; stem leaves 

 3, the blades narrow, involute, 5-12 cm. long, scabrous, the smooth sheaths 

 snorter than the internodes; panicle 10^-30 cm. long, usually open, the capillary 

 branches in whorls of 2-5, flower-bearing above the middle; spikelets shining, 

 greenish or purplish, 2-3 mm. long; lemma hairy at the base, erose-toothed 

 at the apex, bearing a slender awn near the base. 



In moist soils, common. A very variable widespread grass. 



Deschampsia atropurpurea (Wahlenb.) Scheele. Perennial; stems 30-90 cm. 

 high; leaves broad and flat; panicle rather close, purple; spikelets broad, flat, 

 5-6 mm. long. 



In mountain meadows, common. 



Deschampsia calycina Presl. Annual; the slender stems erect, 15-40 cm. 

 tall; leaves narrow, involute, the blades 2-6 cm. long; panicle very loose, 7-20 

 cm. long, with subequal branches mostly in twos, these capillary, branched 

 above and bearing spikelets near the tips; spikelets pale green, sometimes 

 purple-tingled, about 7 mm. long; lemma long-hairy at the base, minutely 

 toothed at the apex, bearing a geniculate awn three or four times as long. 



In dry soil. 



Deschampsia elongata (Hook.) Munro. Stems densely tufted, smooth, 

 30-90 cm. tall; leaves filiform, commonly involute, smooth; panicle narrow, 

 15-45 cm. long, somewhat nodding; branches very unequal, ascending or 

 appressed, very slender, naked below; spikelets pale green, usually purple- 

 tinged near the apex; lemmas hairy at base, shining^irregularly toothed at 

 apex, bearing a slender awn about twice as long. 



Common in open places. 



71. TRISETUM. 



Ours all cespitose perennials; inflorescence a spike-like or 

 open panicle; spikelets 2-4-flowered, the flowers all perfect or 

 the uppermost staminate; rachilla glabrous or with long soft 

 hairs, extending beyond the flowers; glumes unequal, acute, 

 persistent; lemmas 24, usually shorter than the glumes, decidu- 

 ous, 2-toothed, bearing a dorsal awn below the apex or sometimes 

 awnless; palea narrow, hyaline, 2-toothed; grain free, enclosed 

 in the lemma. 



Panicle dense and spike-like. T. spicatum. 

 Panicle loose and spreading. 



Rays long and drooping; sheaths smooth. T. cernuum. 



Rays shorter, erect; sheaths hairy. T. canescens. 



Trisetum spicatum (L.) Richter. Densely tufted, 10-40 cm. high, pubes- 

 cent to glabrous with the sheaths pubescent; panicle oblong-ovate, 5-15 cm. 

 long, shining and often brownish-purple; glumes ciliate on the keels, the lower 

 short; lemma 5-6 mm. long, its awn divergent and about as long. 



In mountain meadows at 1500-2000 m. altitude. 



Trisetum cernuum Trin. Stems 60-100 cm. tall, erect, the nodes pale; 

 leaf blades flat, merely scabrous, 15-20 cm. long, 6-10 mm. wide; panicle 



