Oak woodlands historically experienced near-annual surface fires. As a result, the subcanopy is very sparse in good quality sites, though fire-suppressed sites often contain mesophytic species such sugar maple, red maple, ironwood, hackberry, American elm, and bitternut hickory.
Many other trees are found in these forests, including those of the walnut family, ironwood (Carpinus caroliniana), northern red oak (Quercus rubra), red maple (Acer rubrum), white ash (Fraxinus americana), and slippery elm (Ulmus rubra).