Grass Family 19 



hairy or plumose. Fruit a seed-like grain (caryopsis). 

 Endosperm starchy. 



KEY TO THE TRIBES. 



I. PANICACEAK. Spikelets 1-flowered or with a rudimentary or staminate 



flower below, rarely above, the perfect one; rachilla articulated below 

 the empty glumes. 



Axis of inflorescence articulated; empty glumes firmer in texture than 

 the flowering ones. Tribe 1. ANDROPOGYNKAK. 



Axis of inflorescence not articulated; flowering glumes firmer in texture 

 than the empty ones. Tribe 2. PANICEAE. 



II. POACEAE. Spikelets 1-many-flowered; rachilla usually articulated above 



the empty glumes. 

 Spikelets 1-flowered. 



Spikelets arranged'on one side of a continuous rachis forming a unilat- 

 eral spike. Tribe 6. CHLORIDEAE. 

 SpiUelets not arranged in unilateral spikes. 



Inflorescence spicate; spikelets sessile on alternate notches of the 



rachis. Tribe 8. HORDEAE. 



Inflorescence racemose or paniculate, rarely spicate or apparently 



capitate ; spikelets pedicellate. 

 Glumes 5, the flrst 4 usually empty, the fifth with a hermaphrodite 



flower; palea 1-nerved. Tribe 3. PHALARIDEAE. 



Glumes 3 or sometimes 4, the first two empty : palea 2-nerved. 



Tribe 4. AOROSTIDEAE. 

 Spikelets 2-many-flowered. 



Spikelets pedicellate in panicles or racemes, never unilateral. 



Empty glumes usually longer than the flowering glumes, 1 or more 

 of the latter usually awned on the back or from beneath the 

 teeth of the bifid apex; awn twisted. 



Tribe 5. AVENEAE. 



Empty glumes generally shorter than the flowering glumes, these 

 awnless or with 1-many terminal, rarely dorsal straight or 

 simply divergent awns. Tribe 7. FESTUCEAK. 



Spikelets sessile in true spikes or on very short pedicels in unilateral 



racemes. 

 Spikelets in unilateral spikes or racemes. 



Tribe 6. CHLORIDEAE. 



Spikelets inserted on the alternate notches of the rachis forming 

 equilateral, flattened or cylindric spikes. 



Tribe 8. HORDEAE. 



