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 P. communis 



POA Linne 1753 BLUE GRASS 

 (Gr. poa, grass) 



PL 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. dnnua 



2. Stems perennial, with rootstocks 



a. Stems distinctly flattened and 2-edged P. comprfosa 



b. Stems round, not 2-edged 



(1) Lemma cobwebby at base 



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



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



x. Branches of the panicle reflexed P. reftexa 



y. Branches not reflexed 



(x) Lemmas acute or pointed P. pratensis 



(y) Lemmas obtuse P.fldva 



(2) Lemma not cobwebby 



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



long, 3-4 mm. wide P. alpina 



(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. Lettermdnnii 



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



hairy, especially the nerves P.Pattersdnii 



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 







