AGROPYRUM— AGROSTIS 341 



( 1 ) Spikelets much flattened ; awns spreading, 



v 1-2 cm. long A. spicatum 



(2) Spikelets cylindric or little flattened, awned 



or awnless A.caninum 



2. Stems not in bunches from creeping rootstocks, 

 usually forming a turf 



a. Spikelets much flattened, not densely hairy ; 



awned or awnless A. occidentdle 



b. Spikelets nearly cylindric, or densely hairy 



when somewhat flattened 



(1) Spikelets cylindric, usually smooth, en- 



closed by the glumes or nearly so A. pseudorepens 



(2) Spikelets somewhat flattened, usually 



densely hairy ; glumes half as long as 'the 



spikelets or less A. dasystdchyum 



Agrostis Linne 1753 Redtop, Hair Grass 



(Gr. agros, field, from the habitat) 



PI. 46, fig. 13. 



Spikelets 1-flowered in panicles ; glumes 2, keeled, acute or awned ; 

 lemma obtuse, hyaline, occasionally with an awn on the back, palet shorter, 

 sometimes tiny or wanting ; annual or perennial. 



1. Axis of spikelet extending beyond the palet; 



spikelets 2 mm. long A. thurberidna 



2. Axis of spikelet not extending beyond the palet 



a. Palet distinct, 2-nerved 



(1) Lemma shorter than the glumes 



(a) Stems 1-3 ft. high; panicles open and 



spreading ; lemma without prickle on 



the back A.dlba 



(b) Stems 4-8 in. high ; panicle narrow, 



spike-like ; lemma with a tiny prickle 



on back below the tip A. depressa 



(2) Lemma equalling the glumes; awnless A.humilis 



b. Palet a tiny nerveless scale or none 



( 1 ) Panicle narrow, not spreading ; spikelets 



2-4 mm. long; glumes about equal; lem- 

 ma ]/2-Ya as long as the glumes A. exardta 



(2) Panicle open and spreading; spikelets 1-2 



mm. long; glumes equal; lemma a little 



shorter or equalling the glumes A. hiemdlis 



