234 



COMPAEATIVE ANALYSIS. 



11. Panicle Biuch branched, root creeping 

 Panicle not mucli branched, root fibrons 



BEOirtrs. 



1. Stamens two 

 Stamens three 



2. Leaves auricled, glabrous 



Leaves not auricled, mostly pubescent 



3. Awn much longer than florets . 

 Awn not much longer than florets 



Elatior. 

 Pratensis. 



Biandrus. 



2 

 Giganteus. 



3 



4 



5 



4. Panicle erect in flower, awn twice as long as the florets Maximus. 



Panicle drooping, awn not twice as long as the florets 



5. Florets pubescent .... 

 Plorets glabrous .... 



6. Florets about eight, remote, and longer than the awn 

 Florets nine or more, crowded, as long as the awn 



7. Leaves slightly hairy, panicle spreading 

 Leaves very pubescent, panicle erect, close 



8. Panicle drooping in fruit 



Panicle erect .... 



9. Spikelets lanceolate, awns straight 

 Spikelets ovate, awns not straight 



10. Awns remarkably spreading, leaves pubescent 

 Awns not spreading, leaves slightly hairy 



11. Poot leaves much narrower than the cauline 

 Root leaves not narrower than the cauline 



AVENA. 



1. Spikelets drooping, florets not longer than the calyx 

 Spikelets erect, florets mostly longer than the calyx 



2. Florets terminated by two bristles 

 Florets not terminated by two bristles 



3. Glumes very unequal .... 

 Glumes nearly equal 



4. Leaves downy, sj)ikelets two or three-flowered 

 Leaves not downy, spikelets more than three-flowered 



5. Lower leaves involute 



Leaves flat .... 



6. Sheaths flat, lower part of culm two-edged 

 Sheaths round, culm round 



Aetj>'do. 

 Florets purplish, culm five feet high 



Elymus. 

 1. Leaves flat, florets awncd 



Sterilis. 

 6 

 8 

 Asper. 

 7 

 Velutimis. 

 Mollis. 

 9 

 11 

 Arvensis. 

 10 

 Sqiiarrosum. 

 Secalinus. 

 Erectm. 

 Racemosus' 



2 

 3 



Strigosa. 



Fatua. 



Flavescens. 



. 4 



Pubescens. 



5 

 Pratensis. 

 6 

 Planiculmis. 

 . Alpina. 



Phragmites. 

 Europceus. 



