492 The Ohio Naturalist. [Vol. XII, No. 5, 



(3). Spikelets with but one perfect flower, or monosporan- 

 giate; always in panicles or racemes, not in rows. 



a. Spikelets with 4 or more glumes. 



(a). Third glume enclosing a perfect flower just 

 above the empty glumes ; palet of the perfect 

 flower usually 2-nerved. Tribe, Agrostidece. 



(b). Fifth ghmie enclosing a perfect flower on the 

 top of the spikelet ; palet of the perfect flower 

 usually 1 -nerved or nerveless. 



Tribe, PhalaridecB. 



b. Spikelets usually with but 2 glumes, or the lower 



empty glumes reduced; spikelets often mono- 

 sporangiate. Tribe, Oryzea. 



II. Spikelets usually 2-flowered or by degeneration 1 -flowered; 

 rachilla articulated below the empty glumes which are thus 

 deciduous with the flowers; spikelets more or less dorsally 

 compressed; aerial stems annual. 



Subfamily, Panicatae. 



1. Flowering glumes, at least of the perfect flowers, similar in 



texture to the empty glumes, or frequently coria- 

 ceous or chartaceous (indurated), never thin 

 and hyaline. 



a. Flowering glumes of the perfect flowers chartaceous or 



coriaceous, very different from the empty glumes. 



Tribe, PanicecB. 



b. Flowering glumes membranous. 



(a). Inflorescence paniculate, spikelets deciduous 

 singly from the ultimate branches; first empty 

 glume usually smaller and narrower than the rest. 



Tribe, Tristeginece. 



(b). Inflorescence spikate; spikelets deciduous singly 

 or in groups; first empty glume usually larger 

 than the rest, the second one often spiny. 



Tribe, ZoysiecB. 



2. Flowering glumes thin and hyaline, much more delicate in 



structure than the thick-membranous or coriaceous 

 empty glumes. 



a. Spikelets in pairs, one usually sessile the other pedi- 



cellate, the sessile spikelet with a perfect flower, 

 the pedicellate one with a perfect, staminate, or 

 sterile (vestigial) flower; lemmas of the perfect 

 flowers usually awned. Tribe, Andropogonece. 



b. Spikelets monosporangiate, in separate inflorescences 



or in different parts of the same infloresence, the 

 carpellate portion or inflorescence below, the 

 staminate above; lemmas awnless. 



Tribe, Maydece. 



