GROUP 12 



la. Blade with boat-shaped tip 2 



1 b. Blade tip not boat-shaped 4 



2a. Plants with slender, creeping rhizomes 3 



2b. Plants tufted, without creeping rhizomes 



160. Poa annua — Annual Bluegrass 



Leaves folded in bud-shoot; sheath distnictly flattened, smooth, split 

 with overlapping hyaline margins; auricles absent; collar narrow to 

 broad, divided; ligule membranous, 1 to 2 mm. long, rounded to acute; 

 blade 3 to 6 mm. wide, smooth above, smooth and mostly keeled below, 

 margins smooth and hyaline, tip boat-shaped. Inflorescence — a small, 

 open, few-branched panicle. Common throughout. Lawns, pastures, 

 open ground and waste places. 



3a. Plant bluish-green, somewhat glaucous 



161. Poa compressa — Canada Bluegrass 



Leaves folded in bud-shoot; sheath distinctly flattened, smooth, split 

 with overlapping hyaline margins; auricles absent; collar narrow to 

 broad, divided ; ligule membranous, 1 to 2 mm. long, truncate to rounded ; 

 blade to about 5 mm. wide (occasionally to 7 mm.), smooth above, 

 smooth to somewhat rough and keeled below, margins smooth to rough 

 and hyaline, tip boat-shaped. Inflorescence — a narrow, short-branched 

 panicle. Common throughout. Meadows, open ground and waste places. 



3b. Plant dark green, not glaucous 



162. Poa pratensis — Kentucky Bluegrass 



Leaves folded in bud-shoot; sheath distinctly flattened, smooth or 

 rarely very short hairy, split with overlapping hyaline margins; auricles 

 absent; collar medium broad, divided; ligule membranous, 1 to 1.5 mm. 

 long, truncate; blade to 5 mm. wide, smooth above and below, margins 

 slightly rough, tip boat-shaped. Inflorescence — an open, pyramidal 

 panicle. Common throughout. Lawns, meadows, open ground and waste 

 places. 



4a. Blade glossy and shining below 



163. Lolium perenne — Perennial Ryegrass 



Leaves folded in but-shoot; sheath distinctly flattened, smooth, split 

 with overlapping hyaline margins; auricles small; collar narrow; ligule 

 membranous, 1 to 2 mm. long, rounded to acute, may be toothed ; blade 

 to 6 mm. wide, smooth above, smooth and glossy below, margins smooth 

 to slightly rough. Inflorescence — long, narrow, flat spikes with unawned 

 spikelets placed edge to rachis. Cultivated throughout. 



