AGROPYRUM AGROSTIS 341 



(1) Spikelets much flattened; awns spreading, 



1-2 cm. long A. spicdtum 



(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) 



PL 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. alba 



(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 y2-^4 as long as the glumes A. exarata 



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



mm. long; glumes equal; lemma a little 



shorter or equalling the glumes A. hiemdlis 



