24 GKAMINEAE 



as the flowering glume, with a groove on the back, in which lies an awn- 

 like pedicel about one half its length. 



1. B. erectum (Schreb. ) Beauv. LONG-AWNED WOOD-GRASS. Oc- 

 curs locally in rocky shaded woods near Dodson, Tarsney and Sibley. 



19. PHLEUM L. 



Annuals. Glumes three, the two outer equal, keeled and compressed, 

 truncate at the apex and awued. Flowering glume hyaline, truncate 

 and erose at the summit. 



1. P. pratense L. TIMOTHY-GRASS. Erect, l-3 high, bearing a 

 long cylindric spike 2 / -6 / long : lower glumes ciliate, bearing a short 

 awn. Very common in meadows, along railroads, etc. June-August. 



20. ALOPECURUS L. 



Scales three, the two lower compressed and keeled, about equal, thin, 

 delicate and ciliate. Third scale hyaline, with a delicate awn on the 

 .back, about the length of the empty glumes. Palet thin or wanting. 



1. A. geniculatus L. MARSH FOX-TAIL GRASS. Culms tufted, 

 about 1 high : upper sheath inflated, often partly enclosing the spike : 

 spikes 2'--3' long : flowering glume awned from near its base, the awn 

 -conspicuously exserted. Often common in low wet fields, especially from 

 Adams to Levasy. May-June. 



Var. fulvus (J. E. Smith) Scribn. Awn very delicate, short, barely 

 exserted. Occasionally found along the Missouri River. May-June. 



21. SPOROBOLUS R. Br. RUSH GRASS. DROP-SEED GRASS. 

 Spikelets in open or spike-like panicles, one-flowered, rarely two-flow- 

 ered. Glumes three, membranous, the outer two empty, shorter than the 

 third. Palet similar. Grain free and early deciduous in most species. 

 Leaves long and involute. 



Panicle spike-like. 



Culms stout, 2-5 high. 1. S. compositus. 



Culms slender, 1 or less high. 



Spikelets 2" long. 2. S. vaginaeftorus. 



Spikelets \\" long. 



Sheaths inflated. 3. 8. neglectus. 



Sheaths not inflated. 4. S. cuspidatus. 



Panicle open and with spreading branches. 



Culms erect ; pedicels not longer than spikelets. 



Grain V f in diameter, very conspicuous. 5. S. Jieterolepis. 



Grain not conspicuous. 



Panicle branches widely spreading. 8. S. airoides. 



Panicle branches erect ascending. 



Sheath> densely pilose at summit. 7. 8. cryptandrus. 



Sheaths very sparingly hairy. 6. S. nrgutus. 



Culms decumbent ; pedicels capillary. 9. S. asperifolius. 



1. 8. compositus (Poir. ) Merrill. Stout, tufted perennial: leaves 

 involute, G'-IS 7 long : panicle partly included in the upper sheath, 6' 



