138 VASCULAR PLANTS. 



of a superior one; flowers sessile. Glumes 2, 

 carinate, awnless, larger than the flower. Pa- 

 lets 2; the lower 2 -cleft, dorsally aristate. 

 Ovary sessile ; caryopsis free. 

 0. U. 



19. Arrhenatherum, Beauv. 



Spikelets 3-flowered : lower $ ; middle $ ; 

 upper neutral. Glumes 2, concave, awnless; 

 the upper larger than the lower. Palets of $ 

 flower 2: lower dorsally aristate near the base; 

 upper 2-carinate, awnless. Palets of £ flower 

 2: lower dorsally aristate near the apex; upper 

 adnate to the caryopsis. 



U • leaves flattened; panicles with verticillate 

 branches; spikelets pedicillate. 



20. Holcus, L. 



Spikelets 2-flowered; flowers pedicillate; low- 

 er $ ; upper $ . Glumes 2, navicular. Palets 

 of the £ flower 2; lower navicular awnless; up- 

 per 2-carinate. Ovary sessile, pyriform; cary- 

 opsis free. Palets of the $ flower 2; upper 

 2-carinate; lower aristate near the apex. 



0. U- leaves flattened; panicles branched; 

 spikelets pedicillate. 



21. Phragmites, Trin. 



Spikelets 3 — 6-flowered; flowers distichous, 

 somewhat remote; the lower one $ , the rest £ . 



