GENUS 92. 



GRASS FAMILY. 



253 



Ligule acute, 2" long; flowering scales lanceolate, ij^" long. 

 Ligule truncate, i" long; flowering scales ovate, 2" long. 

 Culms not tufted ; rootstocks long, creeping. 



Flowering scales naked or with short hairs at the base. 



Culms compressed, slender; plant bluish green; spikelets i 

 Culms not compressed, stout ; spikelets above 5" long. 

 Flowering scales with webby hairs at the base longer than scale. 

 Innovations intravaginal, hence plants without rootstocks or stolons. 

 Flowering scales strigose below, hispidulous above. 

 Flowering scales hispidulous all over. 

 Ligules ij4"-2" long, glabrous. 

 Ligules y*"\" long, hispidulous on the outside. 



i. Poa annua L. Annual or Dwarf Meadow- 

 grass. Low Spear-grass. Fig. 604. 



Poa annua L. Sp. PI. 68. 1753. 



Culms 2'-! tall, from an annual root, erect or 

 decumbent at the base, somewhat flattened, smooth. 

 Sheaths loose, usually overlapping; ligule about i" 

 long; blades -4' long, |"-ii" wide, smooth; panicle 

 i'-4' in length, open, branches spreading, i'-ij' long, 

 naked at the base; spikelets 3-5-flowered, ii"-2j" 

 long; lower scales smooth, the first narrow, acute, 

 i-nerved, about two-thirds as long as the broad and 

 obtuse 3-nerved second one; flowering scales iJ"-2$" 

 long, distinctly 5-nerved, the nerves pilose below. 



In waste and cultivated places nearly throughout North 

 America. Naturalized from Europe. Native also of 

 Asia. May-, Six-weeks- or Causeway-grass. May-Oct. 



-3 



21. 

 2O. 



P. pseudopratensis. 

 P. alpina. 



1 9. P. compressa. 

 P. eminens. 

 P. arachnifera. 



23. P. Buckleyana. 



P. laevigata. 

 P. confusa. 



2. Poa Chapmaniana Scribn. Chapman's 

 Spear-grass. Fig. 605. 



P. cristata Chap. Fl. S. States, 562. 1860. Not Walt. 1788. 

 P. Chapmaniana Scribn. Bull. Torn Club 21 : 38. 1894. 



Culms 3'-6' tall, erect from an annual root, simple, 

 rigid, smooth and glabrous. Sheaths tight, mostly at 

 the base of the culm; ligule \" long, truncate; blades 

 i'-i' long, \" wide or less, smooth; panicle i'-2' in 

 length, the branches usually erect, sometimes spread- 

 ing or ascending, i' long or less, naked at the base; 

 spikelets 3~7-flowered, \k"-\\" long; lower scales about 

 equal, 3-nerved, acute ; flowering scales webbed at the 

 base, obtuse, 3-nerved, sometimes with two additional 

 obscure nerves, the prominent ones sometimes pilose 

 for three-fourths their length. 



In dry soil, Virginia to Iowa, south to Florida and 

 Mississippi. April-May. 



X 



3. Poa abbreviata R. Br. Low Spear-grass. 

 Fig. 606. 



Poa abbreviata R. Br. Bot. App. Parry's Voy. 287. 1824. 



Culms 6' tall or less, erect, simple, smooth and 

 glabrous. Sheaths and leaves crowded at the base 

 of the culm; ligule 4" long; blades i'-i' long, \" 

 wide; panicle contracted, i'-i' long, branches very 

 short and erect; spikelets 3-5-flowered, 2.\" long; 

 lower scales acute, smooth and glabrous ; flowering 

 scales about ij" long, obtuse, strongly pubescent all 

 over, the intermediate nerves very obscure. 



Arctic America from Greenland and Labrador to the 

 Pacific. Summer. 



