GRASSES OF OHIO 261 



SYNOPSIS OF THE TRIBES OF GRASSES 



I. Spikelets many-1-flowered ; rachilla usually articulated above the empty glumes 



which are persistent after the fall of the flowers ; spikelets usually more or 

 less laterally compressed. 



1. Aerial stems entirely woody or at least woody at the base, perennial; 



lodicules (perianth segments) often 3; leaf-blade with a short petiole 

 articulated with the sheath. 



Subfamily, Bambusatae. 



a. Tribe, Bambuscae. 



2. Aerial stems herbaceous and annual; lodicules usually 2; leaf-blades sessile, 



without a joint. 



Subfamily, Poacatae. 



(1). Spikelets 2-many-flowered, rarely with 1 perfect an 1 1 staminate 

 flower ; in panicles, spike-like panicles or racemes. 



a. Flowering glumes as long or longer than the empty glumes, 



unawned or with a straight awn from the apex. 



Tribe. Festuceae. 



b. Flowering glumes generally shorter than the empty glumes, usually 



with a bent awn on the back ; callus and usually the rachilla- 

 joints hairy. Tribe, Avcncac. 



(2). Spikelets 1-several-flowered, in rows, forming an equilateral or 1- 

 sided spike or raceme ; sometimes monosporangiate. 



a. Spikelets sessile in 2 opposite rows, forming an equilateral spike; 



leaf-blades bearing at base a more or less well-marked pair of 

 auriculate appendages. Tribe, Hordcae. 



b. Spikelets sessile in 2 rows on one side of a flattened axis, forming 



1-sided spikes which are digitate or paniculate, or sometimes 

 solitary. Tribe, Chlorideae. 



(3). Spikelets with but one perfect flower, sometimes with additional 

 monosporangiate flowers ; always in panicles or racemes, not 

 in rows. 



a. Empty glumes 2, the third glume (lemma) enclosing a perfect 



flower just above the empty glumes ; palet of the perfect flower 

 usually 2-nerved. Tribe, Agrostideac. 



b. With 2 minute glumes (lemmas) above the 2 normal empty 



glumes or sometimes with 2 staminate flowers, the perfect flower 

 on the top of the spikelet ; palet of the perfect flower usually 

 l-nerved or nerveless. Tribe, Phalarideae. 



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



below the empty glumes which are thus deciduous with the flowers ; spike- 

 lets usually 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 coriaceous or chartaceous (indurated), 

 never thin and hyaline. 



(1). Spikelets with 4 or more glumes, more or less dorsally compressed. 



a. Flowering glumes of the perfect flowers chartaceous or coriaceous, 



very different from the empty glumes. Tribe. Paniceae. 



