VASCULAR PLANTS. 137 



U . rhizome creeping; leaves flattened; spikes 

 in our species digitate. 



15. Danthonia, DC. 



Spikelets 2 — co-flowered ; rhachis hairy. 

 Flowers distichous, the uppermost depauperate. 

 Glumes 2, awnless, somewhat longer than the 

 flower. Palets 2: upper 2-carinate; lower con- 

 cave, go -nerved, 2-cleft, aristate. Ovary stipi- 

 tate; caryopsis compressed, free. 



U- turfy; leaves flattened; spikelets pedicel- 

 late, paniculate. 



16. Avena, L. 



Spikelets 3-flowered, the uppermost depau- 

 perate. Glumes 2, awnless. Palets 2: lower 

 2-cleft aristate ; upper 2-carinate awnless. 

 Ovary sessile, hirsute at the apex; caryopsis 

 terete, adherent to the upper palet. . 



17. Trisetum, Kunth. 



Spikelets 2 — 4-flowered, the uppermost de- 

 pauperate. Glumes 2, carinate, awnless, short- 

 er than the flower. Palets 2; lower 2-dentate, 

 aristate. Ovary sessile; caryopsis compressed, 

 free. 



U , leaves flattened. 



18. ira, L- 



Spikelets 2-flowered, often with the rudiment 

 6a 



