POACEAE 



51 



Empty scales awned or awn-pointed. 



Steins creeping : leaf-blades short and broad : ra- 

 cemes or clusters usually of few spikelets. 30. OPLISMENUS. 

 Stems erect: leaf-blades long and narrow: ra- 

 cemes usually of many spikelets. 29. ECHINOCHLOA. 

 Spikelets and their empty scales long-acuminate, the lat- 

 ter not varying much in length and more than twice 

 as long as the fourth scale. 32. PHANOPYRUM. 

 Second empty scale much enlarged, many-nerved, saccate at 



the base. 33. SACCIOLEPIS. 



Palet of the third scale much enlarged when mature, forcing 



open the spikelet. 34. STEINCHISMA. 



2. Spikelets involucrate. 



Involucre of numerous bristles. 



Bristles persistent : spikelets deciduous. 



Bristles not plumose. 35. CHAETOCHLOA. 



Bristles plumose. 39. PENICILLARIA. 



Bristles deciduous with the spikelets. 



Bristles rigid, thickened at the base. 37. CENCHROPSIS. 



Bristles delicate, not thickened at the base, plumose. 38. PENNISETUM. 



Involucre of two spine-bearing valves. 36. CENCHRUS. 



b. Spikelets sunken in one side of the flat rachis. 40. STENOTAPHRUM. 



B. Spikelets monoecious : leaf-blades with a petiole-like base at the junction 



with the sheath. . 41. OLYRA. 



TRIBE VI. ORYZEAE. 

 Spikelets monoecious. 



Inflorescence of short terminal and axillary spikes. 

 Inflorescence paniculate. 



Spikelets in pairs, the larger one sessile and pistillate, the other small 



and staminate, pedicellate. 

 Spikelets not in pairs. 

 Spikelets linear. 

 Spikelets ovate or elliptic. 



Pistillate and staminate spikelets in different panicles. 

 Pistillate and staminate spikelets in the same panicle. 

 Spikelets perfect. 



Empty scales present, manifest. 



Empty scales wanting, or rarely present as minute rudiments. 



42. HYDROCHLOA. 



43. PHARUS. 



46. ZIZANIA. 



44. LUZIOLA. 



45. ZlZANIOPSIS. 



47. ORYZA. 



48. HOMALOCENCHRUS. 



TRIBE VII. PHALARIDEAE. 

 Third and fourth scales empty : 



Awnless. 



Awned upon the back. 

 Third and fourth scales enclosing staminate flowers. 



49. PHALARIS. 



50. ANTHOXANTHUM. 



51. SAVASTANA. 



TRIBE VIII. AGROSTIDEAE. 



A. Flowering scale indurated when mature and very closely embracing the 



grain, or at least firmer than the empty scales; 

 Rachilla not extending beyond the palet. 



Flowering scale 3-awned. 52. ARISTIDA. 



Flowering scale 1-awned. 

 Awn untwisted : 



Stout : spikelets large. 53. ORTACHNE. 



Slender : spikelets small. 55. MUHLENBERGIA. 



Awn twisted. 54. STIPA. 



Rachilla extending beyond the palet. 56. BRACHYELYTRUM. 



B. Flowering scale usually hyaline or membranous at maturity, at least more 



delicate than the empty ones : grain loosely enclosed. 

 Inflorescence a spike. 



Rachilla of the spikelets articulated above the empty scales which are 



therefore persistent. 57. PHLEUM. 



Rachilla of the spikelets articulated below the empty scales, hence de- 

 ciduous entire. 58. ALOPECURUS. 

 Inflorescence an open or spike-like panicle. 



Grain not permanently enclosed in the flowering scale and palet : peri- 

 carp opening readily when mature. 59. SPOROBOLUS. 

 Grain permanently enclosed in the flowering scale and palet : pericarp 

 adherent. 



Spikelets readily falling off entire when mature. 61. POLYPOGON. 



Spikelets with the empty scales at least persistent. 



Palet 1-nerved and 1-keeled : stamen 1. 62. CINNA. 



Palet 2-nerved and 2-keeled : stamens 3. 



Empty scales saccate at the base. 64. GASTRIDIUM. 



Empty scales not saccate at the base. 



Flowering scale with long hairs at the base. 



Flowering scale and palet thin-membranous. 65. CALAMAGROSTIS. 



Flowering scale and palet chartaceous. 



Flowering scale 5-nerved. 66. AMMOPHILA. 



Flowering scale 1-nerved. 67. CALAMOVILFA. 



Flowering scales naked at the base. 



Inflorescence an elongated narrow panicle. 60. EPICAMPES. 



Inflorescence an open, or short and spike-like panicle. 63. AGROSTIS. 



