FESTUCEAE 



137 



64. POA h. Blue Grass, Meadow Grass. 



Annuals. 



Plant h)W. 4 to 8 inches high; branches of 

 panicle spreading. 



Plant taller, erect. 6 to 20 Inches high; 

 branches of panicle erect. 

 Perennials. 



Cobweb at the base of the flowers present, 

 though .sometimes scanty; flowering glume 

 acute (except in i-*. compres^ti) and usu- 

 ally strongly keeled; plants with hori- 

 zontal rootstdcks, never true bunch 

 grasses. 



Intermediate nerves of the flowering 

 glumes strong. 

 Panicles with numerous many-flowered 

 spikelets, the branches in fruit as- 

 cending, the lower ones in 3's and 

 4's; flowering glumes acutish; cob- 

 web copious. 

 Panicles usually with few- flowered spike- 

 lets, the branches reflexed or spread- 

 ing in fruit; flowering glumes very 

 acute. 

 Spikelets few and usually purplish; 

 branches of the panicle few, soli- 

 tary or in pairs; cobweb scanty. 

 Internerves of the flowering glumes 

 long hairy; leaves narrow, more 

 or less inrolled. 

 Internerves of the flowering glumes 

 glabrous, hairs on the mid nerves 

 and lateral nerves copious and 

 spreading. 

 Spikelets many, green; branches of 

 the panicle many, the lower ones 

 often in 3's and 4's. 

 Flowering glumes slightly pubescent 



on the keel below. 

 Fl wering glumes white pubescent on 

 the back below, villous on the 

 marginal nerves and keel. 

 Intermediate veins of the flowering glumes 

 faint or obsolete. 

 Stem compressed; panicles narrow, open. 

 Stems not compressed. 



Branches of the panicle refle.xed. 

 Branches of the large panicle not re- 

 flexed. 

 Cobweb at the bage of the flowers wanting; 

 spikelets acute at the base: empty glumes 

 not very broad nor strongly arched on the 

 back; flowering glumes about 5 mm. 

 long or more; plants tolerably good 

 sized. 

 Spikelets only slightly flattened; flower- 

 ing glumes narrow, nearly straight on 

 the back, r.; inded at the apex; mostly 

 bunch gra;5J^'S with narrow panicles; 

 stem leaves narrow. 

 Flowering glumes merely scabrous 



througout. 

 Flowering glumes more or less strlgose 

 on the lov^.T portion, scabrous above; 

 [ plant yel'io^lsh green. 



1. P. annjia. 



2. P. bigelovii. 



3. /'. prat en sis. 



4. P. arctica. 



5. P. reflexa. 



G. P. occidentalis. 



7. P. traoyi. 



8. P. compressa. 



y. P. aperta. 

 10. P. interior. 



11. P. laevigata. 



12. P. lucida. 



