». GRAMINEAE. 35. 



latter sometimes rudimentary. Lower glumes rigid and 



longer than the florets. 19. 



Spikelets either not in pairs, or if in pairs then the lowest 



glumes not rigid and shorter than the florets. 29. 



19. Spikelets all alike or differing only in the lower glumes. 20. 

 The two spikelets of each pair differing in sex and structure. 



24. 



20. Racemes in a panicle. 2I. 

 Racemes 2 nate, digitate, or fascicled. 23. 



21. Spikelets awned. 3 ERIANTHUS. 



Spikelets awnless. 22. 



22. Panicle silky, spiciform. Rachis not fragile. 1 IMPERATA. 

 Panicle silky much branched. Rachis fragile. 



2 SACCHARUM. 



23. The two spikelets of each pair alike. 4 POLLINIA. 

 The two spikelets of each pair differing in the lower glume. 



5 ISCHAEMUM. 



24. Sessile spikelets sunk in hollows. 25. 

 Sessile spikelets not sunk in hollows. 26. 



25. All the spikelets awnless. 6 ROTTBOELLIA. 



Pedicelled spikelets awned. 7 URELYTRUM. 



26. All the spikelets awnless. 9 ELIONURUS. 



Spikelets not all awnless. 27. 



27. 1 — 3 pairs of perfect and male spikelets subtended by a whorl 



of male or barren spikelets and the whole supported by a 



spathe. II THEMEDA. 



No whorl of male or barren spikelets at the base. 28. 



28. Subsessile spikelets awnless. Pedicelled awned. 



8 TRACHYPOGON. 

 Sessile spikelets awned. 10 ANDROPOGON. 



29. Blades transversely veined. Flowers unisexual. 66 OLYRA. 

 Blades not transversely veined. 30. 



30. Glumes or very minute. 31. 

 Glumes 2, distinct or rarely lower glume absent and upper 



distinct. 32. 



31. Two minute nerveless valves below floret. 



52 POTAMOPHILA. 

 No empty valves. 53 LEERSIA. 



32. One or more empty valves or male florets below fertile floret. 



33. 

 A single fertile floret only. No empty valves. 45. 



33. Two empty valves (sometimes minute) or 2 male or barren 



florets below the fertile floret. 34. 



One empty valve or male floret below the fertile floret. 36. 



34. Lower valve awned dorsally. Awns kneed. 



25 ANTHOXANTHUM. 



