lib. Blade not dense velvety hairy 12 



12a. Sheath short hairy 



197. Avena sativa — Oats 



Leaves rolled in bud-shoot; sheath round, short hairy, split with over- 

 lapping hyaline margins ; auricles absent ; collar narrow, divided, sparse 

 hairy on margins ; ligule membranous, 3 to 4 mm. long, rounded, toothed ; 

 blade to 14 mm. wide, smooth to rough above, keeled and smooth near 

 base but rough near tip below, margins short hairy and hyaline. Inflores- 

 cence — a loose, open panicle. Cultivated. 



12b. Sheath long hairy 



198. Digitaria sanguinalis — Common Crabgrass 



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

 hairy, split with overlapping hyaline margins; auricles absent; collar 

 broad, mostly divided, hairy at least on margins; ligule membranous, 3 to 

 4 mm. long, rounded, may be toothed; blade to 12 mm. or more wide, 

 rough and sometimes hairy above and below, keeled below, margins 

 rough and occasionally hairy. Inflorescence — 3 to 12 digitate spike-like 

 branches. Common throughout. Fields, gardens and waste places. 



13a. Blade rough above 



199. Avena fatua— Wild Oats 



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

 ping hyaline margins; auricles absent; collar broad, may be divided; 

 ligule membranous, 3 to 5.5 mm. long, rounded, mostly toothed; blade 10 

 to 20 mm. wide, rough above, smooth near base and rough near tip below 

 with midrib prominent, margins rough and hyaline and in young plants 

 sometimes hairy near base. Inflorescence— a loose, open panicle. Rare in 

 Northeast. Cultivated fields and waste places. 



1 3b. Blade smooth above at least near base 



200. Avena sativa — Oats 



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

 ping hyaline margins; auricles absent; collar broad, divided; ligule mem- 

 branous, 3 to 4 mm. long, rounded, toothed; blade 10 to 14 mm. wide, 

 smooth near base and rough near tip above and below, keeled below, 

 margins rough and hyaline. Inflorescence — a loose, open panicle. Cul- 

 tivated. 



58 



