COMPARATIVE ANALYSIS. 



Spikelcts with one perfect floret . . Uniflora. 



3. Leaves much shorter than the purplish panicle . Ccerulea. 



Leaves much longer than the pale panicle . Dcpauperata. 



(M. cacrulca B. Hooker.} 

 HOLCUS. 



Awn longer than the calyx, joints of culm downy . Mullis. 



Awn not longer than the calyx, joints not downy . Lanatm. 



ARRHEN ATIIERUM . 



Spikelets greenish brown . . . Avenaceum. 



HlEROCHLCE. 



Florets awnless ..... Borealis. 



SESLERIA. 

 Spike bluish, ovate ..... Carulea. 



PANIC UM. 



Spikes alternate . . Crus-galli. 



SETARIA. 



Bristles of involucre, with reflexed teeth . Verticillata. 



Bristles of involucre, with erect teeth . . Viridis. 



GLYCERIA, (PoA, Hooker?) 



1. Florets with seven or more ribs. . . 2 

 Florets with not more than live ribs . . .3 



2. Panicle much branched, plant four feet high . Aquatica. 

 Panicle slightly branched, plant not more than three feet 



high ..... Fluitans. 



3. Panicle compact, rigid ... 4 

 Panicle spreading, not rigid . . .6 



4. Root creeping . . Maritima. 

 Root fibrous . . . . .5 



5. Florets four or five, five-ribbed, plant procumbent . Procumlens. 

 Florets six or seven, nearly ribless, plant erect, or ascending Rigida. 



6. Panicle reflexed in fruit . . . Distans. 

 Panicle not reflexed in fruit . . . JJorreri. 



POA. 



1. Florets webbed . . 2 

 Florets not webbed . . . .7 



2. Stem bulbous at base . . . Bullosa. 

 Stems not bulbous at base . . . .3 



3. Culm much compressed, spikelets five or more flowered Comprcssa. 

 Culm round, or but little compressed, spikelets three or 



four-flowered . . 4 



