COMPARATIVE ANALYSIS. 



237 



Avena. — Florets with two long bristles at summit 

 Florets without bristles at summit 



CrNosuKtrs. — Outer palea terminating in a short awn, not 

 half length of palea . 

 Outer palea terminating in a long awn, as 



long as the palea 



PoA.- 



Florets webbed .... 



Florets not webbed 



1. Upper leaf much longer than sheath 

 Upper leaf about as long or longer than sheath 



2. Ligule of upper sheath short and rounded 

 Ligule of upper sheath long and pointed 



3. Ligule scarcely perceptible, outer palea five-ribbed . 

 Ligule prominent, outer palea three-ribbed 



4. Florets hairy at base .... 

 Florets not hairy 



5. Outer palea three-ribbed 

 Outer palea five-ribbed 



6. Panicle erect, upper leaf linear, folded 

 Panicle drooping, upper leaf lanceolate, flat 



7. Upper joint situated above centre of stem 

 Upper joint situated below centre of stem 



8. Second sheath not reaching to first joint . 

 Second sheath extending beyond first joint 



9. Small glume reaching beyond base of third floret 

 Small glume not reaching beyond base of second floret 



10. Eachis and branches rough 

 Eachis and branches smooth 



11. Eachis and branches rough to touch 

 Eachis and branches smooth to touch 

 Glumes with a prominent lateral rib on each side 

 Glumes without lateral ribs 

 Lower half of central rib of outer palea smooth 

 Central rib of outer palea rough the whole length . 



14. Summit of upper glume reaching to base of third floret 



12. 



13 



15. 



16. 



Strigosa. 

 Fatua. 



Cristalm. 

 EcMnatus. 



1 

 . 4 

 2 

 3 

 Pratensis. 

 . Trivialis. 

 NemoralU. 

 ( 'ompressa. 

 5 

 12 

 6 

 7 

 Alp in a. 

 Laxa. 

 8 

 9 

 Polynoda. 

 Montana. 

 10 

 11 



Ccesia. 

 . Annua. 

 Distans. 

 Maritima. 

 Procnmbens. 

 13 

 . 14 

 15 

 Rigida. 



Summit of upper glume reaching to base of fourth floret Loliacea. 

 Outer palea three-ribbed . . . Sylvatica. 



Outer palea seven-ribbed . . . 16 



Panicle compound, spikelets not a quarter of an inch in 



length . . . . . Aquatica. 



Panicle simple, spikelets an inch in length . . Fluitans. 



