Genus 92. GRASS FAMILY. 255 



7. Poa pseudopratensis Scribn. & Ryd. Prairie Meadow-grass. Fig. 610. 



Poa pseudopratensis Scribn. & Rydb. Contr. Nat. 

 3: 531. 1896. 



Herb. 



Culms i°-2j° tall, erect, simple, smooth and gla- 

 brous. Sheaths shorter than the internodes, smooth 

 or slightly rough; ligule 2" long, acute, decurrent; 

 blades i"-3" wide, smooth beneath, a little rough 

 above and on the margins, those of the culm i'-zV 

 long, the basal 6'-io' in length; panicle 2'-$' long, 

 open, the branches spreading or ascending, 1 '-2' long; 

 spikelets 3-5-flowered, 3"-4" long, exceeding their 

 pedicels; lower scales nearly equal, acute, 3-nerved; 

 flowering scales acutish, about ii" long, rough above, 

 S-nerved, pubescent between the nerves below, the 

 marginal nerves and midnerve silky-pubescent about 

 half their length. 



Manitoba and Assiniboia to Nebraska and Colorado. 



8. Poa trivialis L. Rough-stalked Meadow-grass. Fig. 611. 



Poa trivialis L. Sp. PI. 67. 1753. 



Culms i°-3° tall, usually more or less decumbent at 

 the base, simple, smooth or slightly scabrous. Sheaths 

 usually shorter than the internodes, rough ; ligule 2"s" 

 long, acutish; blades 2-7' in length, l"-2" wide, gener- 

 ally very rough; panicle 4'-6' long, open, the branches 

 usually spreading or ascending, i'-2' long; spikelets 2- 

 or sometimes 3-flowered, ii" long, exceeding their pedi- 

 cels ; scales acute, the empty basal ones rough on the 

 keel, the lower i-nerved, shorter than the 3-nerved 

 upper; flowering scales i"-li" long, webbed at the base, 

 5-nerved, the midnerve silky-pubescent below, the lateral 

 nerves naked, the intermediate ones prominent. 



In meadows and waste places, Newfoundland to Ontario, 

 South Carolina and Louisiana. Naturalized from Europe. 

 Fowl or Round-stalked Meadow-grass, Natural grass, Bird- 

 grass. June-Aug. 



9. Poa debilis Torr. Weak Spear-grass. Fig. 

 612. 



Poa debilis Torr. Fl. N. Y. 2: 459. 1843. 



Culms i°-2i° tall, erect, slender, simple, somewhat 

 flattened, smooth and glabrous. Sheaths compressed, 

 much shorter than the internodes; ligule i'-i" long; 

 blades i'-4i' long, 1" wide or less, erect, smooth be- 

 neath, rough above; panicle 2-6' in length, open, often 

 nodding at the top, the branches erect or ascending, 

 sometimes spreading, ii'-3' long; spikelets 2-4-flow- 

 ered, iJ"-2" long, their pedicels longer; empty scales 

 unequal, acute, the first i-nerved, shorter than the 

 3-nerved second one; flowering scales \\" long, obtuse, 

 sparingly webbed at the ' base, S-nerved, the nerves 

 naked. 



In woods, Quebec and Ontario to Rhode Island, Penn- 

 sylvania, Illinois and Iowa. June-Aug. 



