GRAM1NACEAE (GRASS FAMILY) 



9 a Spikes 4-sided ; plants cultivated for their grains .... 10 



b Spikes more or less cylindric n 



10 a Leaves glaucous; spikelets 2-3-flowered. . 7. Secale. p 118 

 b Leaves not glaucous; spikelets 4-5-flowered 



8. Triticum. p 118 



11 a Each spikelet surrounded by awn-like bristles 



10. Chaetochloa. p 118 

 b Spikelets not surrounded as in a 12 



12 a Spikelets each with a barbed awn 2-4 in. long 



9. Hordeum. p 118 

 b Spikelets not completely as in a 13 



13 a Spikelets with i or more awns V in. or more long 



ii. Elymus. p 118 

 b Spikelets not completely as in a 14 



14 a Spikes rather ovoid, about twice as long as broad 



54. Phalaris. p 122 

 b Spikes elongated 15 



15 a Spikes somewhat flattened; spikelets about % in. long; 



plant fragrant when drying 38. Anthoxanthum. p 120 



b Spikes not flattened; spikelets less than V in. long.... 16 



16 a Spikes 1-3 in. long, soft, velvety 12. Alopecurus. p Il8 

 b Spikes 2-7 in. long, not soft and velvety 13. Phleum. p Il8 



17 a Spikelets in flattened or i-sided spikes or racemes .... 18 

 b Spikelets in spreading or compressed panicles 40 



18 a Spikelets overlapping, arranged in numerous, spreading 



reflexed spikes l A-% in. long on a single axis 



14. Atheropogon. p 118 

 b Spikelets not arranged completely as in a 19 



19 a Spikelets in i spike or raceme 20 



b Spikelets in 2 or more spikes or racemes 30 



20 a Spikelets bur-like, with sharp spines 15. Cenchrus. p 118 

 b Spikelets not bur-like 21 



21 a No conspicuous awns Ys in. or more long on spikelets. . 22 

 b Conspicuous awns % in. or more long on spikelets.... 26 



22 a Spike somewhat ovoid, about twice as long as broad 



54. Phalaris. p 122 

 b Spike or raceme elongated 23 



23 a Spikelets rounded, flat on inner surface, in 2-4 rows, 



compact 23. Paspalum. p IIQ 



b Spikelets not rounded and flat on inner surface 24 



24 a Coarse grass usually 4 ft. or more high ; rachis easily 



breaking at the joints where spikelets are attached 



16. Tripsacum. p 118 

 b Grasses less than 4 ft. high ; rachis not easily breaking 



at joints 25 



8 11 



