The red maple, cottonwood and river birch are all trees native to Illinois. Illinois has over 20 species of oak trees, including the white oak, which is the state's official tree. Nineteen percent of Illinois's original forests remain intact and native trees grow extensively throughout the state's two natural forest preserves and 142 state parks.
Southern Illinois contains many swamps and waterways where the state's largest and oldest baldcypress trees are located. The state's hardwood forests are made up of trees that include the overcup oak, pin oak, sweetgum and cherrybark oak. Other trees native to the state's wide range of habitats and ecosystems include the American beech, American elm, sycamore, tuliptree and pawpaw. Other native species include buckeyes, holly, spicebush, sugar maple, red oak and sweetgum.
The white oak tree grows throughout every one of Illinois's 102 counties, although Putnam County holds the State Champion white oak. These trees can grow up to 100 feet in height and typically grow to about 4 feet in diameter. These trees produce leaves that are yellow and green in color and are popular for their shade and purplish fall foliage. White oak trees tolerate a wide range of soil types and conditions and are even hardy enough to withstand limited drought conditions.