VEGETATION REGIONS xxi 



existing in the midst of the entirely different flora of the deciduous 

 forest. 



The most abundant shrubs of the deciduous forest are the dog- 

 woods, especially Cornus paniculata, sumacs, thorn apples, black haw, 

 Rosa blanda and in somewhat sterile soil, the common hazel. 



The prairies occupy the southwestern quarter of the state, ex- 

 tending thence eastward almost to the Mississippi, and northward 

 through the Red River valley into Manitoba. It is notable that the 

 line between the prairies and the hardwood forests is much sharper 

 north of the Minnesota river than south of that stream, a fact prob- 

 ably due to the grouping of the numerous lakes in the former region 

 and their scarcity in the latter. Throughout the prairie region of the 

 state, trees occurred naturally only along river valleys and in groves 

 about lakes. The commonest trees are the cottonwood, box-elder and 

 white elm, though numerous others occur, especially in the south. The 

 bur oak is the only oak which extends far into the prairie parts of the 

 state, and there it is often scarcely more than a bush. 



The most characteristic shrubs of the prairie district are the 

 Amorphas, roses, especially Rosa arkansana, hazel, and in the extreme 

 western part of the state, the buffalo berry, Shepherdia argentea. 



