138 TUE TRUE GRASSES. 



1°. Fertile spikelets one-flowered, sterile 

 spikelet with obtuse glumes. 



254. Lamarckia. 



2°. Fertile spikelets 2-3-flowered, sterile 



spikelet with awned or pointed glumes. 



253. Cynosurus. 

 II. Spikelets all alike. 



1°. Flowering glumes tin ee-toothed, three- 

 pointed or two-toothed, usually three- 

 nerved; lateral nerves and the callus 

 usually hairy. 



* Spikelets with only one fertile 

 flower, four empty glumes and one 

 upper, empty, three-awned rudi- 

 ment. . . . 218. Blepharidachne. 



** Spikelets with three to many fertile 

 flowers ; empty glumes two. 



219. Triodia. 

 *** Spikelets 1-3-flowered ; ' flowering 

 glumes keeled ; branches of the 

 diffuse panicle very long and capil- 

 lary 219a. Redfieldia. 



Note. — Compare JJiplachne with its sharp- 

 keeled flowering glumes. 



2°. Flowering glumes of some other struc- 

 ture. 



* Flowering glumes 1-3-nerved, all 

 with flowers, or the uppermost 

 onty with a $ flower, or empty. 



t Panicle-branches spirally ar- 

 ranged. 



O Panicle-branches in sjDike- 

 like racemes either with 

 short-pedicelled or sessile 

 spikelets. 



<| Flowering glumes keeled. 

 220. Diplachne. 

 C] <] Flowering glumes round- 

 ed on the back. 



224. Ipnum. 



