Jones: Flora of Illinois 7 



graphic feature in the state. The axis of the ridge Hes along an east- 

 west line across the southern part of the state from Jackson and Union 

 counties to Gallatin and Hardin counties. The highest point is Wil- 

 liams Hill in Pope County, with an elevation of 1065 feet. The flora 

 of the Ozark Hills has been little affected by the Illinois ice-sheet, 

 which apparently did not reach beyond the northern edge of the area. 

 There are several species of vascular plants which have not extended 

 their ranges northward in Illinois and are therefore peculiar to this 

 part of the state. Some of these plants are: Polypodmrn pulypudioides, 

 Pinus echinata, Smilax bona-nox, Ulmus alata, Magnolia acuminata, 

 Sedurn pulchellum. Rhododendron roseum, and \'accinium arhoreurn. 



TERTIARY DIVISION 



The Mississippi Embayment of the Coastal Plain of the south 

 Atlantic and Gulf states extends into Illinois as far as the southern 

 base of the Ozark Hills. The tertiaiy deposits in the bottomlands of 

 Alexander, Pulaski, and Massac counties contain a number of austro- 

 riparian species that have not migrated northward into the glaciated 

 areas. Some of these are: Taxodium distichum, Arundinaria gigantea, 

 Quercus phellos, Planera aquatica, Itea virginica, Wisteria macro- 

 stachya, Nyssa aquatica, Bumelia lycioides, and Bignonia capreolata. 



