22 



GRASSES OF IOWA. 



North America. New York, Pennsylvania, Connecticut, Mary- 

 land (Holm) ; Glen Echo, D. C. (Kearney) ; to Illinois, Iowa, 

 Missouri (Eggert) ; St. Louis (Panimel) ; Florida (Jacksonville, Cur- 

 tiss; Duval County, Curtiss) ; Arkansas, Texas and Mexico. 



General. Trinidad and Brazil. 



TRIBE II. ANDRO^OGONE^. 



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

 rachis, one sessile and hermaphrodite, one pedicellate, the latter hermaph- 

 rodite, staminate, neuter, or reduced to the pedicel alone; glumes 



usually four, the first and 

 second empty, larger and 

 much firmer in texture than 

 the others, the third usually 

 empty, with a staminate 

 flower in the axil, very 

 rarely awned, the fourth or 

 flowering glume hyaline, 

 usually awned, awn usually 

 twisted or geniculate. 



This tribe contains up- 

 wards of 400 species di- 

 vided among 29 genera, of 

 which Andropogon con- 

 tains 190 species. This is 

 one of the largest and most 

 important because they 

 make excellent forage 

 plants. Several of these 

 Fig. 15. Spikelets of A ndropogon furcat us. plants are used in medicine. 



Sugar cane (Saccharum) belongs to this tribe. Well known representa- 

 tives of this tribe are blue stem {Andropogon provincialis, A. nutans). 

 Sorghum, of which there are many varieties, is a well known plant cul- 

 tivated in Iowa. 



KEY TO THE GENERA OF THE ANDROPOGONEAE. 



Spikelets all alike, perfect (homogamous). 



Axis of racemes continuous; racemes in somewhat fan-shaped panicles. 



— M1SCANTHUS. 1 

 Axis of racemes articulate; racemes in an elongated, dense panicle. 



Spikelets awned ER1ANTHUS. 2. 



Spikelets awnless SACCHARUM. 3. 



Spikelets not all alike, the sessile perfect; the pedicellate staminate, empty or re- 

 duced ANDROPOGON. 4. 



