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. Chrysopogon. 



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 witliin 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 

 Panicese, but the awn twisted and bent as in Andropogoneae. 



Glumes four, two empty, the third with a male 



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



Primary Series B. POACEiE. — Spikelets not articulate below the outer 

 glumes. Phachis 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 Phalaridese the lower glumes are deficient.) 



Tribe IV. — PirALAMDEiE. — 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 oues ... ... ... ... ... 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. 



