Savannas consist of widely spaced trees, mainly oaks with occasional hickories, growing over an open understory and a thick ground cover of prairie grasses and wildflowers. Because they typically occur in association with prairies, you could describe savannas as basically prairies with trees. Woodlands, by comparison, have a more closed overstory of trees but maintain an open understory. This allows enough sunlight to reach the ground to favor a group of sedges, grasses, low shrubs and wildflowers that do best in a woodland environment. Like savannas, woodland canopies contain primarily oaks, but they also have hickories and sometimes shortleaf pine in the Ozarks.
Woodlands can occur in association with prairies, but more frequently they exist surrounding glades.
True forests, as opposed to woodlands, have a heavy overstory canopy and a thick understory. Multiple layers of canopy trees and shade-adapted shrubs and saplings occur. Forests contain more fire-sensitive trees and shrubs, such as northern red oak, sugar maple and American hornbeam. Forests explode in the spring with an emerald carpet of ferns and colorful spring wildflowers. But by mid-summer the forest floor becomes rather drab.