The Gymnocladus dioicus, better known as the Kentucky Coffee tree is a tree in the subfamily Caesalpinioideae of the pea family Fabaceae, native to the midwest of North America, primarily in southern Michigan and Ohio as well as southwest to Iowa, Kansas, Oklahoma and Arkansas. The Kentucky coffee tree was the state tree of Kentucky from 1976 to 1994.
These trees vary from 18 to 21 meters (60–75 feet) high with a spread of 12–15 meters (40–50 feet) with a trunk up to one meter (3 feet) in diameter. The Kentucky Coffee is a moderately fast-growing tree. With the healthy trees living from 100 to 150 years, this tree is normally long-lived; however for the first six months of the tree’s growth, they often appear dead. This is due to the Kentucky Coffee tree shedding its leaves early during the fall, appearing bare for up to 6 months. When the leaves are attached, they appear bright pink, but turn green to bronze when aged. The bark is similar to black cherry with it’s ash-gray and scaly texture. A Kentucky Coffee tree bears fruit in a hard-shelled bean that is in heavy pods made from wood that are filled with sweet, gooey pulp that is thick. The shape of the pods varies somewhat: pod length ranges from about 5 to 10 inches (130 to 250 mm); unfertilized female trees may bear miniature seedless pods. The seed pods are too difficult for many animals to chew through, and they are too heavy for either wind or water to disperse them. The beans contain the toxin cytisine, which can interfere with breathing, resulting in death in cases of heavy doses. The plant is toxic to some animals.
The Kentucky Coffee is a great landscaping tree for large lawns and parks. The male trees are generally considered more desirable because of the lack of seedpods. However, mature female trees with hanging seedpods can be very attractive in winter.
In the summer and winter, the ascending branches often form a narrow crown. Oval leaflets form in late spring, changing from pinkish to a dark blue-green. The Kentucky Coffee tree tolerates most conditions including drought and pollution. This tree is best grown in moist, organically rich, well-drained soils in full sun. However, avoid heavy clays.