TEHON: FIELDBOOK OF NATIVE ILLINOIS SHRUBS 5 



bogs are spread over a considerable territory and present a 

 remarkable and for Illinois a unique type of shrub association, 

 which includes Purple Chokeberry, Vacciniums, Poison Sumac 

 and Sweetfern. 



Sands. — Remarkable also are the small and large sand regions. 

 There are six of real importance, and together they cover many 

 hundreds of square miles. The Havana sand area covers some 

 20 per cent of Mason County and extends northward into Taze- 

 well and across the Illinois River into Fulton and Peoria coun- 

 ties. In Jo Daviess and Carroll counties, there is the region 

 along the Mississippi River known as the Sand Prairies, and in 

 Lee, Bureau and Henry counties, along the lower course of 

 the Green River, are the Green River sands. Along the Missis- 

 sippi River in Henderson and Mercer counties, the Oquawka 

 sand lands are extensive, and in southeastern Kankakee and 

 northern Iroquois counties the St. Anne sands stretch for miles. 

 The somewhat lesser region of Wilmington sands lies in Will 

 and Grundy counties. There are smaller areas in Whiteside 

 County, in northern Winnebago, in eastern Ogle, in Cass and 

 in Lawrence counties. Sands such as the Green River, Havana, 

 Wilmington and St. Anne are the outwash from glaciers; some 

 others are the result of disintegration by wind, rain and sun of 

 St. Peter sandstone, now represented at Castle Rock, Starved 

 Rock and elsewhere. 



The Ozarks. — Across the southern part of the state runs an 

 extension of the Ozark Mountains, with numerous summits 

 approaching 1,000 feet above sea level. Here diverse formations 

 of sandstone, limestone and shale are exposed, and great irreg- 

 ularities in topography provide a wide variety of habitats favor- 

 . able to many kinds of plants. The shrub flora in this region 

 has not been investigated as carefully as might be wished, but 

 it is among the richest in the state in diversity of kinds and in 

 abundance. 



The Ohio Valley. — South of the Ozarks lies a flat region, in- 

 cluding essentially Alexander, Pulaski and Massac counties, 

 which in Tertiary times formed the northern tip of the Gulf of 

 Mexico. Many of the herbs, trees and shrubs that grow in this 

 region are so typically southern that they are known best as 

 Gulf Coast inhabitants. Here are to be found woody Clematis 

 and Wisteria, Crossvine, Virginia Willow, the Bumelias and 

 numbers of other interesting species. Northward along the 



