INTRODUCTION 



THE number of kinds of shrubs and woody vines that grow 

 in Illinois as natives and as naturalized introductions is 

 surprisingly large. Definite mention is made in the following 

 pages of 210 species and 27 varieties. These represent 77 gen- 

 era and are distributed among 43 botanical families. In Indiana, 

 the only nearby state in which the shrubs have been cataloged 

 separately, there are about 150 species, and in Minnesota, 

 among about 275 native and cultivated woody species, approxi- 

 mately 160 are native shrubs. 



This large variety in Illinois is, however, to be expected. 

 Geographically, the state is so located as to include sections of 

 the eastern deciduous forest, extensive prairies, remnants of 

 the northern forest, and a remarkable representation of the 

 Gulf Coast forest. Illinois extends some 380 miles north and 

 south and more than 200 miles east and west. In the north- 

 east it borders on Lake Michigan, and on much of its periphery 

 it is bordered by large rivers, some of them the greatest on 

 this continent. In altitude, it ranges from about 280 feet above 

 sea level at the Ohio River to about 1,250 feet at Charles 

 Mound, in Jo Daviess County; and the average elevation is 

 about 700 feet. Most of the state has been subject to glacial 

 action, but the extreme northwest corner, essentially Jo Daviess 

 County, and the Ohio valley in the south, have not been influ- 

 enced by glaciers. Both the extension of the Ozark Mountains 

 in the south and the hills of the northwest present a great var- 

 iety of physical conformations and favor a great and varied 

 display of plant species. 



Shrub Habitats. — ^All of the above factors and many others 

 besides have given rise to great diversity of habitats. Some habi- 

 tats are extensive and cover very large areas of land. In them 

 the shrub population is relatively uniform. Others are smaller 

 and specialized; and in them the shrubs usually are different 

 from those occurring nearby. Not infrequently small, special- 

 ized habitats support shrubs found nowhere else in the state. 



The predominant shrub habitats of the state, both as to 

 areas covered and number of kinds of shrubs, were formerly the 

 prairie and deciduous forest regions. Most of the prairies and 



[3] 



