332 American Midland Naturalist Monograph No. 7 



5. Stems slender, ascending from a decumbent base; panicle 

 5-15 cm long, the branches ascending, pale green; leaves 

 4-8 mm wide; second glume S-nei'ved, obtuse; swampy 



ground, s. 111., rare. June-July G. pallida (Torr.) Trin. 



4. Spikelets 2-3 mm long, 1.5-2 mm wide, usually 3-5-flowered; 

 leaves 2-6 mm wide; glumes 1 -nerved, 0.5 mm long; wet 



ground, the common species throughout 111. May- July 



- G. striata (Lam.) Hitchc. 



7. Pea L. — Blue Grass. Meadow Grass 



1. Perennials; stem 30-120 cm tall. 



2. Plants with conspicuous horizontal rhizomes. 



3. Stems terete, 30-120 cm tall; leaves bright green; panicle 

 open, 5-20 cm long, the ascending or spreading branches 

 in whorls of 3-5 ; lemmas 3 mm long, copiously webbed at 

 base; roadsides, lawns, fields, and woods, very common. 

 May- June. Kentucky Blue Grass P. pratcnsis L. 



3. Stems compressed above, 30-40 cm tall; leaves bluish green; 



panicle narrow, 3-8 cm long; leinmas 2-2.5 mm long, 

 scarcely webbed; roadsides, cultivated ground, waste 

 places, common; nat. from Eurasia. June-July. Canada 



Blue Grass P. compressa L. 



2. Plants without horizontal rhizomes. 



4. Lemmas glabrous, except the webbed base ; damp woods, n. 



III., rare; Cook and Jo Daviess counties. June-Aug 



P. languida Hitchc. 



4. Lemmas puberulent or pubescent, at least on the keel and 

 marginal nerves. 

 5. Lemmas webbed, i.e., with a tuft of soft hairs at base. 

 6. Lemmas apparently S-neived, the intermediate nerves 

 obscure or obsolete. 

 7. Panicles 5-10 cm long, the lower branches mostly in 

 pairs; ligule 1-1.5 mm long; wet ground, n.e. 111., 

 rare P. paludigena Fern. & Wieg. 



7. Panicle 10-30 cm long, the lower branches inostly fas- 



cicled; damp meadows, locally in the n. half of 111. 



July-Aug P. palustris L. 



6. Lemmas distinctly 5-nerved. 



8. Spikelets 3-4 mm long; lemmas 2-3 mm long. 



9. Lemmas glabrous except the keel; panicle-branches 

 ascending with nimierous crowded spikelets; 

 roadsides, waste places, occasional; Stark Co., 

 V. H. Chase in 1907; Cook Co., E. K. Chord in 

 1948 P. trivialis L. 



9. Lemmas pilosulous on the marginal nerves and keel; 

 panicle with slender divaricate branches bearing 

 a few spikelets above the middle; woods and 



