PHRAGMITES— POA 



.359 



flower; lemma narrow, long-pointed, much exceeding the palet ; reed-like 



swamp perennial. 



Stems 5-15 ft. high; panicle .5-1.5 ft. long; flowering 



scales 10-12 mm. long 

 P6a 



P. communis 



L.inne 1753 Blue Grass 

 ( Gr. poa, grass) 

 PI. 45, fig. 21. 

 Spikelets 2-6-flowered, in panicles, flattened, flowers mostly perfect ; 

 glumes keeled, 1-3-nerved ; lemma longer than the glumes, often cobwebby- 

 hairy at base, 5-nerved, the nerves usually hairy; palets usually shorter, 2- 

 nerved or 2-keeled ; annual or perennial. 



1. Stems annual, i.e., without rootstocks, tufted, 2-8 



in. high ; lemma 5-nerved, not cobwebby at base P. annua 



2. Stems perennial, with rootstocks 



a. Stems distinctly flattened and 2-edged 



b. Stems round, not 2-edged 

 (1) Lemma cobwebby at base 



(a) Panicle small, 2-4 cm. long 



(b) Panicle large, 5-15 cm. long 

 x. Branches of the panicle reflexed 

 y. Branches not reflexed 



(x) Lemmas acute or pointed 

 (y) Lemmas obtuse 



P. compressa 



P. laxa 



P. reflexa 



P. pratensis 

 P. Mva 



(2) Lemma not cobwebby 



(a) Panicle 2-4 cm. long; leaves 2-4 cm. 



long, 3-4 mm. wide P. alptna 



(b) Panicle 4-15 cm. long; leaves 5-20 cm. 



long, 1-3 mm. wide 

 x. Stems 1-8 in. high; at 11000-14500 ft. 

 (x) Stems 1-4 in. high ; lemma smooth 



or nearly so P. Lettermann'u 



(y) Stems 4-8 in. high; lemma very 



hairy, especially the nerves P. Patter s6)ili 



y. Stems 1-4 ft. high, at 4-11000 ft. 

 (x) Spikelets distinctly flattened - 

 m. Flowers perfect 



(m) Plants tufted, without root- 

 stocks ; panicle narrow, 

 dense, green to purple ; 

 glumes more or less un- 

 equal P. subaristdta 



