10 



Spikelets in single or few pairs or triplets on the 

 slender branches of a more or less compound 

 panicle. 



Panicle long and dense, usually cylindrical, the 

 spikelets awnless, concealed under long 

 silky hairs ... ... ... ... 30. Imperata. 



Panicle loose. Fertile spikelets awned. 



Outer glume either membranous or narrow 

 and rigid with two prominent often 

 muricate lateral nerves... ... ... 31. Chrysopogoii. 



Outer glume when in fruit hard, smooth 



and shining, ovate or lanceolate ... 32. Sorghum. 

 Spikelets in triplets (one sessile and fertile between 

 two pedicellate and male neuter or rudi- 

 mentary) within sheathing bracts. 

 Triplets surrounded by an involucre of four male 

 or neuter spikelets at the base of the 

 peduncle... ... ... ... ... 33. Anthistiria. 



Triplets sessile or pedunculate within the bract 



without any involucre 34. Apluda. 



Subtribe V. Tristeginese. Spikelets paniculate, all similar, the terminal 

 flowering glume more or less stiffened or enlarged when in fruit almost as in 

 Panicea3, but the awn twisted and bent as in Andropogonea?. 



Glumes four, two empty, the third with a male 



flower or empty. Panicle Joose ... 35. Arundinella. 



Primary Series B. POACE.ZE. Spikelets not articulate below the outer 

 glumes. Bhachis of the spikelet articulate above the two or three lowest 

 glumes, or wholly continuous. Spikelets with one or more fertile flowers, the 

 males or imperfect ones, if any, above or very rarely below them. 



(In a few Phalaridea3 the lower glumes are deficient.) 



Tribe IV. PHALARIDEJE. Spikelets with one terminal bisexual flower 

 and rarely two male flowers lower down. Glumes two to six, all keeled or 

 with a central nerve, two below the articulation of the rhachis persistent or 

 in several genera deficient, four or fewer above the articulation, of which two 

 enclose the grain without any distinctly two-nerved palea. 



Stamens six, rarely three. No glumes below the 



articulation. 

 Spikelets very flat. Glumes two, without any 



small ones 38. Leersia. 



Spikelets not flattened. Glumes four, mem- 

 branous, the two outer very small ... 40. Potamophila. 

 Stamens six or four, very rarely three or two. Two 



persistent glumes below the articulation. 

 Stamens four, rarely two. Spikelets paniculate, 



more or less awned ... ... .. 42. Microlsena. 



Stamens four. Spikelets not awned 43. Tetrarrhena. 



Stamens three, rarely two. Glumes three, none below 



the articulation. 



Flowering glume awned. Panicle dense, cylin- 

 drical, spike-like ... 44. Alopecurus. 



