1918] The Grasses of Illinois 273 



j. Panicle narrowly pyramidal; spikelets 

 8 to 10 mm. long, not pendulous. 



37. Arrhenatherum 

 jj. Panicle about as broad as long; spike- 

 lets 2 cm. long or more, pendulous 

 (oats). 36. Avena 



ii. Florets 7 to 12, awned from between the teeth 

 of a bidentate apex. 38. Danthonia 



hh. Spikelets not over 5 mm. long. 



i. Lemmas bearing delicate dorsal awns; panicle 

 branches capillary, flexuous. 



35. Deschampsia 



ii. Lemmas awnless, or obscurely awn-tipped. 



j. Glumes dissimilar, the second broadly 



wedge-shaped or obovate; spikelets 



falling entire. 33. SplienophoUs 



jj. Glumes similar, acute, persistent after the 



fall of the florets. 34. Eoeleria 



gg. Glumes shorter than the lowest floret. • 



h. Culms woody perennial; plants shrubby; blades 



narrowed into a short petiole above the sheath. 



63. Anindinaria 

 hh. Culms herbaceous; plants not shrubby; blades 

 sessile on the sheath, 

 i. Plants usually 6 to 12 feet tall, the culms 

 strong, reed-like, with stout, creeping root- 

 stocks; panicle large, feathery at maturity. 



46. Phragmites 

 ii. Plants rarely 5 feet tall, the culms not reed- 

 like; panicle not feathery, 

 j. Lemmas 3-nerved. 



k. Spikelets short-pediceled along one 

 side of a slender rachis, forming 

 elongate racemes, these arranged 

 in a rather open panicle. 



45. Leptocliloa 

 kk. Spikelets not in 1-sided racemes. 

 1. Lemmas glabrous, not lobed; 

 nerves not excurrent. 



49. Ero.grostis 

 11. Lemmas hairy on the nerves be- 

 low, lobed at the apex; mid- 

 nerve excurrent. 

 m. Panicle usually large, 

 spreading; lateral nerves 

 of the lemmas excur- 

 rent; palea not fringed. 

 47. Tridens 

 mm. Panicle small, few-flow- 

 ered; lateral nerves of 

 the lemmas not excur- 

 rent; palea conspicuously 

 fringed. 48. Triplasis 

 jj. Lemmas 5- to many-nerved (the interme- 

 diate obscure in Poa alsodes). 

 k. Upper floret unlike the lower, folded 

 together forming a club-shaped 

 mass; spikelets pendulous, fall- 

 ing entire. 50. Melica 

 kk. Upper florets like the lower; spike- 

 lets sometimes drooping, not pen- 

 dulous. 



