POACEAE. 19 



longitudinally dehiscent. Ovary 1-celled, 1-ovuled; 

 styles 1-3, usually 2 and lateral; stigmas hairy or plu- 

 mose. Fruit a seed-like grain (caryopsis). Endosperm 

 starchy. 



Key to the Tribes. 



Spikelets 1-flowered or with a rudimen- 

 tary 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. Andropogoneae. 



Axis of inflorescence not articulated; 

 flowering glumes firmer in texture 



than the empty ones. Tribe 2. Paniceae. 



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 unilateral spike. Tribe 6. Chlorideae. 



Spikelets not arranged in uni- 

 lateral spikes. 

 Inflorescence spicate; spike- 

 lets sessile on alternate 



notches of the rachis. Tribe 8. Hordeae. 



Inflorescence racemose or 

 paniculate, rarely spi- 

 cate or apparently capi- 

 tate; spikelets pedicel- 

 late. 

 Glumes 5, the first 4 usu- 

 ally 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. Agrostideae. 



Spikelets 2-many-flowered. 



Spikelets pedicellate in panicles 

 or racemes, never uni- 

 lateral. 

 Empty glumes usually longer 

 than the flowering glumes, 

 1 or more of the latter usu- 

 ally awned on the back or 

 from beneath the teeth of 

 the bifid apex; awn twisted. Tribe 5. Aveneae. 



