36. ». GRAMINEAE. 



Valves awnless or awned from the tip. Awns straight. 35. 



35. Empty valves minute enclosed by the glumes. 



55 PHALARIS. 

 At least one of the empty valves larger than the fertile. 



54 EHRHARTA. 



36. Glumes not falling with the spikelet. 37. 

 Spikelets falling entire with the glumes. 39. 



37. Spikelets in clusters of three, large. 24 TRISTACHYA. 

 Spikelets solitary. 38. 



38. Spikelets less than one-fifth inch. Upper valve minutely 2 



toothed or entire. 22 ARUNDINELLA. 



Spikelets l/6th- — V/z inches. Upper valve distinctly 2-toothed 



or 2 lobed. 23 TRICHOPTERYX. 



39. Spikelets subtended by bristles 1 or many. 4O. 

 Spikelets not subtended by bristles. 4I. 



40. Bristles persistent. 17 SETARIA. 

 Bristles falling with the spikelet. 18 PENNISETUM. 



41. Glumes or lower valve 2 lobed or emarginate, muticous or 



awned from the sinus. Lower glume minute or 0. 42. 



Glumes and lower valve entire awnless or awned. 



Lower glume distinct. 43. 



42. Upper glume 5 nerved, tips obtuse. 20 TRICHOLAENA. 

 Upper glume 7 nerved, tips acute. 21 MELINIS. 



43. Glumes subcqual with long viscous awns. 15 OPL1SMENUS. 



Glumes usually unequal, awnless or with short scabrid awns. 



44- 



44. Inflorescence of 2 — 5 stout racemes. 16 AXONOPUS. 

 Inflorescence a loose, rarely contracted panicle. 



14 PANICUM. 



45. Glumes awned. 46. 

 Glumes awnless or shortly mucronate. 47. 



46. Valve 1 nerved. 36 PEROTIS. 



Valve more than 1 nerved. 31 POLYPOGON. 



47. Valves awned. 48. 

 Valves awnless. 51. 



48. Awns of valve 3 or 3 branched. 34 ARISTIDA. 

 Awns of valve solitary. 49. 



49. Nerves of valve closely approaching or joining at tip. 

 Awn kneed. 35 STIPA. 

 Nerves of valve parallel, not joining at tip. 50. 



50. Valve decurrent into a callus which has hairs several times 



longer than the valve itself. 33 CALAMAGROSTIS. 



Callus glabrous or minutely hairy. 32 AGROSTIS. 



51. Lower glume minute or 0. Upper glume with hooked spines 



or bristles. 37 TRAGUS. 



Both glumes distinct without spines or bristles. 52. 



