86 THE TRUE GRASSES. 



fi. Spikelets not in pairs at the nodes of the 

 branches. 

 I. Spikelets without empty glumes. 



1°. Spikelets linear. Embryo as long as 



the fruit 83. Zizania. 



2°. 9 spikelets ovate or elliptical. Em- 

 bryo many times smaller than the fruit. 

 * $ and 9 spikelets in different pani- 

 cles, rarely in the same, and then the 

 $ spikelets terminal on each branch. 



81. Luziola. 

 ** $ and 9 spikelets in the same pani- 

 cle, the 9 terminal, the $ at the 

 base of each branch. 82. Zizaniopsis. 

 II. Spikelets with two very small or bristle- 

 like empty glumes. . . 84. Potamophila. 

 B. Spikelets all % . 



a. Spikelets arranged in panicles. 



a. Empty glumes two, short but distinct, awnless 

 (two additional rudimentary empt} r glumes in 

 Oryza). 



I. Flowering glume and palea roundish in 

 section (but slightly compressed). 



85. Maltebrunia. 

 II. Flowering glume and palea much com- 

 pressed laterally 86. Oryza. 



/?. Empty glumes tavo, awned, exceeding or slightly 

 shorter than the flowering glume. 

 * Empty glumes gradually tapering into awns. 



58. Achlsena. 

 ** Empty glumes awned from a notch in the 



apex 89. Reynaudia. 



y. Empty glumes wanting or present only as 

 minute rudiments. 



I. Flowering glume awnless. . 87. Leersia. 

 II. Flowering glume awned. . 90. Hygroryza. 



b. Spikelets in a terminal, naked spike at whose apex 

 the ends of the awns of all the spikelets are fast- 

 ened together 93. Streptochseta. 



