4a. Sheath hairy at least at top or base 5 



4b. Sheath not hairy 7 



5a. Sheath distinctly flattened 



57. Cenchrus pauciflorus — Field Sandbur 



Leaves rolled in bud-shoot ; sheath distinctly flattened, smooth with a 

 tuft of hairs at throat, split with overlapping hyaline margins; auricles 

 absent; collar narrow to broad, hairy on margins; ligule a fringe of hairs, 

 .6 to 1 mm. long; blade 3 to 5 mm. wide, rough above, smooth near base 

 and rough near tip below, margins slightly rough to rough and hyaline. 

 Inflorescence — a nearly round, hairy bur with sharp spines. Through- 

 out. Sandy open ground. 



5b. Sheath not distinctly flattened 6 



6a. Blade generally rough above 



58. Danthonia spicata — Poverty Oatgrass 



Leaves folded in bud-shoot; sheath round to somewhat flattened, 

 hairy at least at top or base, split with overlapping hyaline margins; 

 auricles absent; collar mostly narrow and hairy at least on margins; 

 ligule a fringe of hairs, mostly .2 to .6 mm. long (occasionally to 1 mm.) , 

 sometimes with longer hairs to 3 mm. long; blade 3 to 5 mm. wide, 

 smooth to rough above, mostly smooth and glossy below but occasionally 

 short hairy, margins rough and hyaline. Inflorescence — a narrow pan- 

 icle with stiff, short branches bearing one spikelet. Common throughout. 

 Sandy and sterile or rocky soil. 



6b. Blade generally smooth above 



59. Danthonia compressa — Mountain Oatgrass 



Leaves folded in bud-shoot; sheath round to somewhat flattened, 

 hairy at least at top, split with overlapping hyaline margins; auricles 

 absent; collar narrow, may be hairy at least on margins; ligule a fringe 

 of hairs, .2 to .4 mm. long but occasionally with longer hairs; blade 2 to 

 5 mm. wide, mostly smooth above at least near base but may be long 

 hairy, smooth to occasionally long hairy below, margins smooth to rough 

 and somewhat long hairy. Inflorescence — a narrow panicle with stiff, 

 short branches bearing 2 or 3 spikelets. Throughout. Meadows and 

 open woods. 



7a. Blade long hairy below at least near base 



60. Danthonia sericea — Downy Oatgrass 



Leaves folded in bud-shoot ; sheath round, smooth, split with overlap- 

 ping hyaline margins; auricles absent; collar broad, may be hairy; ligule 

 a fringe of hairs, .6 to 1 mm. long; blade 3 to 5 mm. wide, smooth to 

 rough above, long hairy below at least near base, margins rough or long 

 hairy. Inflorescence — a narrow panicle with stiff, short branches bear- 

 ing 2 to 6 spikelets. Massachusetts south, chiefly Coastal Plain. Sand 

 barrens. 



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