Interior River Valleys and Hills

The Interior River Valleys and Hills follows the broad bottomlands and wooded bluffs of the Mississippi, Illinois, Ohio, and Wabash rivers through Illinois, Indiana, and Kentucky, taking in Peoria, Springfield, Evansville, and Terre Haute. Rich alluvial soil on the flats gives way to steep timbered slopes, and spring flooding is part of the pattern rather than an exception. Natives like prairie milkweed, rose-mallow, and clustered mountain-mint are built for ground that stays wet into spring and bakes dry by August.

Conditions: Deep alluvial bottomland soils below wooded bluffs, 38–48 inches of rain, wet springs and dry late summers, cold winters.

Cities and areas: Peoria, Springfield, Evansville, Terre Haute, Quincy, Paducah.