138 THE 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 thiee-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 witli 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 IMplachne 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 

 only with a $ flower, or empty. 



t Panicle-branches spirally ar- 

 ranged. 



O Panicle-branches in spike- 

 like racemes either with 

 short-pedicelled or sessile 

 spikelets. 



<3 Flowering glumes keeled. 

 22O. Diplachne. 

 3 < Flowering glumes round- 

 ed on the back. 



224. Ipnum. 



