20 Andropogoneae 



Tribe 1. ANDROPOGONEAE. SORGHUM TRIBE. 



Spikelets in spike-like racemes, 2 at each joint of the 

 rachis, 1 pedicellate and hermaphrodite, staminate or 

 rudimentary. Glumes usually 4, the first and second 

 empty, large and much firmer in texture than the others, 

 the third usually empty or with a staminate flower in 

 its axil, rarely awned, the fourth or flowering glume 

 hyaline, usually awned, the awn generally twisted or 

 geniculate. 



Inflorescence composed of spike-like silky racemes. 1. ANDROPOGON. 



Inflorescence paniculate ; spikelets somewhat silky-pubescent. 



2. SORGHUM. 



1. ANDROPOGON L. 



Slender or rather coarse perennials with solid culms. 

 Spikelets heterogamous, in pairs at each joint of the 

 articulate and usually hairy rachis, one of each pair ses- 

 sile, hermaphrodite and 1-flowered, the other pedicellate 

 and staminate or rudimentary. Glumes of the fertile 

 spikelet 4, the first coriaceous, flattened on the back with 

 a strong nerve near each margin and usually with 

 fainter ones between, second glume hyaline awned. 

 Stamens 3. Styles distinct ; stigmas plumose. Grain 

 unfurrowed, free within the hardened outer glumes. 



1. A. glomeratus (Walt.) B. S. P. Culms erect, 4-6 dm. high, 

 smooth, simple below, much branched above, upper nodes of 

 branches barbed; sheaths compressed, glabrous or pubescent; 

 leaves 2-4 mm. wide, scabrous, long acuminate, nearly equaling 

 the culms, those of the culms 15-45 mm. long; branches elon- 

 gated, forming a compact terminal inflorescence; spikes in pairs, 

 about 25 mm. long, loose, protruding from the sides of the 

 scabrous sheaths ; rachis flexuous, the joints and pedicels pubes- 

 cent with long spreading silky hairs ; outer glume about 3 mm. 

 long; awn 12-18 mm. long, scabrous; pedicelled spikelet reduced 

 to a single scale or wanting. (A. macrourus Michx.) 



Rubio and Eaton's Canyons, San Gabriel Mountains, McClatchie. 



