The state tree of Illinois has been the white oak, or Quercus alba, since 1973. Previously, the state tree was the native red oak, but it was changed after 900,000 school children were polled to select the official symbol. This is a deciduous tree, which means that it sheds its leaves in the fall of each year. Native to the eastern portion of North America, this species is widely found throughout the Midwest. The town of Rochelle and the grounds of the governor's residence are two the sites where the "official" state trees are on display.
The state tree of Illinois is not a very tall tree, reaching a maximum height of about 100 feet (30 meters). Typically, this tree grows to about 65 to 85 feet (about 19.5 to 25.5 m) in height, and it can sometimes be wider than it is tall. Despite the tree's name, the color of its bark is not white, but light gray. The bark can be flaky and often peels, with smoother areas seen in patches in some older trees. The bright green leaves of the white oak are typically 5 to 9 inches long (about 13 to 23 centimeters).
White oaks usually grow best in rich soil that is well drained, on slopes and on terraces. They tend to thrive in lower elevations, though they are also found in some areas of the Appalachian Mountains. Mountainous trees, however, do not grow as easily, and may appear only as shrubs. The state tree of Illinois may live as long as 600 years.
Reddish colored flowers appear within the leaves of this species in early spring. In the autumn, the leaves turn to shades of red or purple before falling off the tree. White oaks also produce acorns in the fall, starting at about 20 years of age, that mature annually. Acorns produced by the state tree of Illinois are an important food source for many animals and birds. The tree is also important to birds such as the woodpecker, that find bugs easily under its flaky bark.
The light brown wood of this tree is hard, durable, and beautiful, making it popular as a commercial wood. It is often used in making cabinetry and flooring, and is a staple of mission style furniture. In Japan, this wood is used to create weapons used in martial arts because of its strength and resistance to splintering.