315 



4. Spikelets two to many flowered. 



5. Flowering glumes usually shorter 

 than the empty ones, usually with 

 a bent awn on the back, rarely 



awned from the apex IX. Avicnk.-h 



5. Flowering glumes generally longer 

 than the empty ones, unawned, or 

 with a straight awn from the apex.. XI. Fksti tk.t: 

 3. Spikelets in two rows. 



4. Spikelets crowded on one side of the con- 

 tinuous rhachfs, forming one-sided spikes 



or racemes X. Chloride.*: 



4. Spikelets in two opposite rows of the often 

 articulate rhachls, forming equilateral 



spikes ■. XII. Hokpk.i: 



2. Stems wocdy ; leaf-blade with a petiole-like base which is 



articulated with the sheath XIII. IIamuiish.k 



Tribe I. MAYDEiE. 



1. Staminate spikes numerous in terminal panicles; pistillate 

 spikes in the axils of the leaves subtended by large 

 membranous bracts at the base. 



2. Pistillate spikes of each leaf-axil free, articulated .... ( 1 ) Suchlaena 

 2. Pistillate spikes of each leaf-axil grown together 

 into a continuous, compound, and much thickened 



axis (2) Zra 



1. Staminate spikes solitary at the ends of the branchlets ; 

 pistillate below, one to two, each of them reduced to a 

 single spikelet entirely inclosed by the ovoid or spher- 

 ical, ivory-like sheath of the subtending bract (4) Coi.r 



1. Staminate and pistillate spikelets in the same spike, 



the lowest glume of the pistillate spikelets indurated.. (8) CMoHOChlM 



Tribe II. ANDROPOGONETE. 



1. Spikelets homogamous, hermaphrodite; joints of the rha- 

 chis not much thickened nor excavated for the reception 

 of the spikelet. 



2. Axis of the racemes continuous. 



3. Spikelets solitary, disposed in several slender 



unilateral racemes (5) Dimeria 



3. Spikelets »in pairs, rarely in threes, upon 

 each joint of the rhachis, paniculate. 

 4. Racemes in a narrow, usually spike- 

 like panicle; spikelets awnlesa (<>) Imperata 



4. Racemes in a board panicle ; spike- 

 lets usually awned (7) Miacanthua 



2. Axis of the racemes articulate. 



3. Racemes solitary, terminal. 



4. Spikelets in pairs at each joint of 



the rhachis ( 1 1 > Pogonatherum 



4. Spikelets in threes at each joint of 



the rhachis (10) Poly trtot 



3. Racemes two to many, digitate or approxi- 

 mate on a shortened main axis. 



i. Spikelets one, rarely two-flowered ; 

 when two flowered the first empty 

 glume with a median longitudinal 



furrow (9) Pollinia 



4. Spikelets two-flowered, the first empty 



glume without a longitudinal furrow.. ( 1 5 ) 1st haemum 

 3. Racemes in a much-branched panicle upon 

 an elongated main axis, the lateral racemes 

 sessile ; (8) Saccharum 



