10a. Plants with large creeping rhizomes, only in salt marshes 



92. Spartina alterniflora — Smooth Cordgrass 



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

 lapping margins hairy; auricles absent; collar broad, indistinct; ligule a 

 fringe of hairs, 1 to 2 mm. long; blade 10 to 12 mm. wide, smooth above 

 and below, margins smooth and hyaline. Inflorescence — a series of comb- 

 like spikes forming an appressed panicle. Maine south along coast. Salt 

 marshes, often in water. 



10b. Plants without creeping rhizomes 



93. Setaria viridis — Green Foxtail 



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

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

 narrow to broad, divided, sometimes hairy; ligule a fringe of hairs, 1 to 

 2 mm. long; blade 8 to 15 mm. wide, rough above, smooth to somewhat 

 rough below, margins rough and hyaline. Inflorescence — dense, bristly, 

 cylindrical, green or purplish, erect, spike-like. Common throughout. 

 Cultivated soil and waste places. 



1 1 a. Ligule 3 mm. or less long 12 



1 1 b. Ligule more than 3 mm. long 17 



1 2a. Sheath hairy at least at top 13 



1 2b. Sheath not hairy 15 



13a. Sheath dense velvety short hairy 



94. Panicum scoparium — Velvety Panicum 



Leaves rolled in bud-shoot ; sheath round, dense velvety short hairy, 

 split with overlapping margins hairy; auricles absent; collar medium 

 broad to broad, hairy; ligule a fringe of hairs, 1.5 to 3 mm. long; blade 

 10 to 20 mm. wide, short velvety hairy above and below, margins short 

 hairy. Inflorescence — an open, many branched panicle with sticky 

 blotches on axis and branches. Massachusetts south. Wet or damp soil. 



13b. Sheath smooth, hairy at top only 14 



14a. Blade smooth above, long hairy near base 



95. Panicum amaralum — Bitter Panicgrass 



Leaves rolled in bud-shoot; sheath round, smooth and hairy at top, 

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

 divided; ligule a fringe of hairs, 2 to 3 mm. long, fused at base; blade 10 

 to 13 mm. wide, smooth above with long hairs near base, smooth and 

 midrib prominent below, margins rough and hyaline with a few long 

 hairs. Inflorescence — a large, compact, densely flowered, slightly nod- 

 ding panicle. New Jersey south. Sandy shores and coast dunes. 



• 31 



