13 



27. Spikelels in pairs, usually one sessile, the other pedi- 



celled, the latter sometimes rudimentary. Lower 

 glume rigid and longer than the florets. (Trib. Andro- 



pogoneae) 28 



Spikelets either not in pairs or if in pairs then the lower 

 glume not rigid and shorter than the florets ... 39 



28. Spikelets all alike or differing only in the lower glume 29 

 The two spikelets of each pair differing in sex and 



structure 33 



29. Racemes in a panicle 30 



Racemes 2 nate, digitate or fascicled 32 



30. Spikelets awned Erianthus. 



Spikelets awnless 31 



31. Panicle silky, spiciform. Rachis not fragile 



Imperata arundinacea. 

 Panicle silky, much branched. Rachis fragile ... 



Saccharum munroanum. 



32. The two spikelets of each pair alike in all respects. 



PoUinia. 



The two spikelets of each pair differing in the lower 



glumes Ischaemum. 



33. Sessile spikelets sunk in hollows 34 



Sessile spikelets not sunk in hollows 35 



34. All the spikelets awnless Rottboellia compressa var. 



fasciculata. 

 Pedicelled spikelets awned Urelylrum squarrosum. 



35. Lower floret of sessile spikelet always male 



' Ischaemum glaucostachyum. 

 Lower floret of all spikelets empty 36 



36. All the spikelets awnless Elionurus argenteus. 



Spikelets not all awnless 37 



37. 1-3 pairs of perfect and male spikelets subtended by a 



whorl of male or barren spikelets, and the whole sup- 

 ported by a spathe Anthistiria imberbis. 



No whorl of male or barren spikelets at the base ... 38 



38. Sub-sessile spikelets awnless. Pedicelled awned. 



Trachypogon polymorphus. 

 Sessile spikelets awned Andropogon. 



39. Blades transversely veined. Flowers unisexual. 



Olyra latifolia. 

 Blades not transversely veined 40 



40. Glumes or very minute (Tribe Oryzeae) 41 



Glumes 2 distinct, or rareXy lower glume absent, and 



upper distinct 42 



