The Flora of the Cayuga Lake Basin 57 



h. Spikelets 5-12 mm. long, sometimes longer in a few species ; flower- 

 ing glumes entire, often awned at apex, with no more than 5 

 nerves ; grain glabrous, often free from the palet. 



3. Festuca 

 g. These nerves not converging at apex ; flowering glumes obtuse. 



5. Puccinellia 



/. Nerves of the flowering glumes prominent, raised, not converging at the 

 apex. 4. Glyceria 



e. Flowering glumes keeled, often with cobwebby hairs at the base. 



6. Poa 

 d. Spikelets in dense 1-sided clusters on the rays of the panicle. 



10. Dactylis 

 c. Flowering glumes 3-nerved (see also Poa with one pair of nerves obscure), 

 muticous, not cobwebby at base; spikelets in open panicles (see also 3d c). 



7. Eragrostis 



c. Flowering glumes 1-3-nerved, short-awned, not cobwebby at base ; spikelets 

 in elongated, racemosely disposed, spikes. 8. Diplachne 



b. Rhachilla covered with long silky hairs which at maturity exceed the glumes ; 

 plant tall, reed-like, 1.5-4 m. high. 9. Phragmites 



ci. Spikelets unisexual, clustered, the terminal member of each cluster pistillate and 

 with broad glumes, the lateral members staminate and with many very narrow 

 glumes; inflorescence a spike-like panicle. 11. Cynosurus 



Tribe 2. Hordeae 

 a. Spikelets solitary at each joint of the rhachis, 2-many-flowered. 



b. Spikelets placed flatwise to the rhachis ; both empty glumes developed. 



12. Agropyron 

 b. Spikelets placed edgewise to the rhachis ; empty glume adjacent to the rhachis 

 wanting. 13. Lolium 



a. Spikelets 2 or 3 at each joint of the rhachis, placed edgewise. 

 b. Spikelets at each joint similar, all 2-6-flowered and fertile. 

 c. Empty glumes well developed ; spikes rather dense. 14. Elymus 



c. Empty glumes minute or wanting ; spikes very open, with divaricate spikelets. 



15. Asperella 

 b. Spikelets at each joint dissimilar, the central spikelet 1-flowered and fertile, the 

 lateral one sterile and rudimentary. 16. Hordeum 



Tribe 3. Aveneae 

 a. Empty glumes very unequal, one enlarged and often obtuse ; spikelets 3-4 mm. 



long. 17. Sphenopholis 



a. Empty glumes nearly equal. 

 b. Awn dorsal or wanting. 

 c. Awns not hooked ; plant not velvety. 



d. Spikelets 22-25 mm. long. [Avena] 



d. Spikelets 7-8 mm. long. 18. Arrhenatherum 



d. Spikelets 4-5 mm. long. 19. Deschampsia 



c. Awns hooked at tip, at least when dry ; plant velvety. 20. Ginannia 

 b. Awn from between the two apical teeth. 21. Danthonia 



Tribe 4. Agrostideae 



a. Flowering glumes as thin as or thinner than the empty glumes ; spikelets laterally 

 compressed or subterete. 

 b. Rootstocks not densely scaly ; flowering glumes dorsally awned or awnless. 

 c. Empty glumes slightly compressed, not wing-carinate ; panicles open or con- 

 tracted, but not very dense. 



