262 OHIO BIOLOGICAL SURVEY 



(a). Inflorescence paniculate, spikelets deciduous singly from the 

 ultimate branches ; first empty glume usually smaller and 

 narrower than the rest. Tribe, Tristegineae. 



(b). Inflorescence spikate; spikelets deciduous singly or in groups: 

 first empty glume usually larger than the rest, the second 

 one often spiny. Tribe, Zoysicae. 



(2). Spikelets laterally compressed, with but 2 normal glumes, the empty 

 glumes reduced or wanting; spikelets often monosporangiate. 



Tribe, Oryzeae. 



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 pedicellate, 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, Andropogoneae. 



b. Spikelets monosporangiate, in separate inflorescences or in different 



parts of the same inflorescence, the carpellate portion or inflores- 

 cence below, the staminate above ; lemmas awnless. 



Tribe, Maydeae. 



SYNOPSIS OF THE GENERA IN EACH TRIBE 



The number after the generic name refers to the list number. 

 Festuceae. 



Rachilla and flowering glumes glabrous or with hairs shorter than the glumes. 

 A. Spikelets all alike. 



1. Lemmas 5-many-nerved. 



(1). Spikelets not in dense 1-sided clusters. 



((1)). Stigmas arising below a cushion-like appendage at the tip 



of the ovulary. Bromus. (1) 

 ((2)). Stigmas arising at or near the tip of the ovulary. 



a. Spikelets with 2 or more of the upper glumes empty, broad, 



and enfolding each other. Melica. (2) 



b. Spikelets with the upper glumes flower-bearing, or if 



empty similar in shape to the other glumes, 

 (a). Lemmas rounded on the back; at least below. 



((a)). Lemma acute, pointed or awned at apex, its 



nerves not prominent. Fcstuca. (3) 

 ((b)). Lemma obtuse or subacute at the apex, usually 

 toothed, its nerves prominent. 



Panicularia. (4) 

 (b). Lemmas more or less strongly compressed and 

 keeled. Poa. (5) 



(2). Spikelets nearly sessile in dense 1-sided clusters. Dactylis. (6) 



2. Lemmas 1-3-nerved, rarely with faint additional nerves. 



(1). Callus and nerves of the lemma glabrous or cobwebby, or the 

 callus sparingly bearded. 



