[Chap. LIU THE VEGETATION OF NORTH AMERICA 765 



wet and drier areas of the corn belt and extended northward to Manitoba 

 and southward to Texas. The deep, dark soils that developed under the 

 grasses are among the most fertile in the world; and the vast population 

 of big bluestem, Indian grass, little bluestem and slough grass have long 

 since been destroved and replaced by crop plants. The Gulf coastal 



Fig. 390. Little bluestem {Andropogon scopariii.s) , a dominant grass of the 

 dry prairie areas. Like the tall bluestem, it grows in dense stands and also as a 

 bunch grass. Photo by H. L. Shantz. 



prairies have become rice fields. Farther inland cotton is cultivated and 

 to the northward sorghums and winter wheat. Corn is the prevailing crop 

 in the middle region, while spring wheat, barley, Hax, and hay grasses 

 are the important crops northward. Alfalfa and other legumes are widely 

 planted and thrive without irrigation. 



The mixed prairie is composed of grasses up to 4 feet in height in- 

 cluding needle grass, dropseed, little bluestem, June grass, wheat grass, 

 side oat grama and several shorter ones. Most of these grow as "bunch" 

 grasses, but some are sod formers in moist situations. Among the grasses 



