958 Gymnocladus dioicusCommon Names: Kentucky coffee tree Family: Fabaceae (bean Family)
Kentucky coffee tree is a medium sized tree with very large twice compound (bipinnate) deciduous leaves and a narrow oval or rounded crown. It normally grows 60-70 ft (18.3-21.3 m) in height, although it can get up to 100 ft (30.5 m) tall. It has a straight trunk with ascending branches. The leaves are up to 3 ft (0.9 m) long and 2 ft (0.6 m) wide, developing quite late in spring and dropping rather early in fall. The leaflets are oval, 2-3 in (5.1-7.6 cm) long, and rather widely spaced along the rachis. The leaflets turn yellow and drop in fall, leaving the bare midribs hanging on the twigs for several weeks longer. The bark is dark gray-brown and furrowed into narrow scaly ridges which often project to one side. The branches are stout and asymmetrical and the twigs are noticeably thick with orange colored lenticels (raised dots on the twigs that facilitate gas exchange).
Kentucky coffee tree is usually dioecious, meaning that male and female flowers are on separate trees. The flowers are greenish white with 5 petals, and are not particularly showy. The male flowers have 10 stamens and are arranged in elongated clusters 3-4 in (7.6-10.2 cm) long; female flowers have a single pistil and are in elongated clusters 10-12 in (25.4-30.5 cm) long. The flowers appear in May or June and last for a week to 10 days. The dark reddish brown legumes are hard and woody, 5-10 in (12.7-25.4 cm) long and about 2 in (5.1 cm) wide. Inside, the hard, shiny brown seeds are surrounded by a dark brown sticky pulp. The pods often persist on the tree through late winter. There have been a few selections named, but the tree is still largely ignored in the horticultural trade.
Kentucky coffee tree, Gymnocladus dioicus, is native to Midwestern North America. It grows in bottomlands, ravines, and lower slopes of the Appalachian Mountains from western New York and western Pennsylvania, west to southern Wisconsin, and south through Kentucky, Tennessee, Arkansas, eastern Oklahoma and northern Louisiana. Kentucky coffee tree grows with other hardwoods such as honeylocust (Gleditsia triacanthos), hackberry (Celtis occidentalis) and cottonwood (Populus deltoides), and is never very abundant in any one location. In fact, Kentucky coffee tree is usually scattered and rather uncommon in the wild.
CultureKentucky coffee tree is a moderately fast growing tree that should reach 20 ft (6.1 m) in height after 15 years; 50 ft (15.2 m) in 40 years; and 70 ft (21.3 m) at maturity, around 60 years. It will grow in acidic or alkaline soils that are moderately moist or even fairly dry. Light: Full sun. Moisture: Kentucky coffee tree does best in a well drained, rich soil with adequate moisture. However, it can tolerate normal droughts. Hardiness: USDA Zones 5 - 8. Propagation: Seeds can be sown in fall in containers and left outdoors. The hard seed coat should be nicked with a file or sharp knife before planting. Professional nurserymen soften the seeds by soaking in concentrated sulfuric acid before planting. Cultivars are propagated from root cuttings taken in winter.
Kentucky coffee tree is usually cultivated as a specimen tree for its huge leaves in summer, its autumn color, and its bold and picturesque winter form, characterized by stout, asymmetrical branches. It is well suited as a lawn tree because it is attractive in all seasons and casts only light shade in summer. Kentucky coffee tree is useful as an urban tree and for street plantings since it is very tolerant of air pollution, salt and drought. Female trees are, however, messy in fall when they drop their pods. Male cultivars, which do not produce pods, are becoming available in the trade. This is a handsome North American native tree that deserves to be more widely used. The reddish brown wood is hard and durable and very attractive when finished and polished. It is used in cabinet making. Early settlers made a coffee substitute from the roasted seeds. Infusions of the roots and bark were used by Native Americans as a laxative.
The name, Gymnocladus, means "naked branch." There are just two or three species in the genus: this one and one or two that occur in central China.
Although the roasted seeds were once used as a (reportedly poor) substitute for coffee, the raw seeds are poisonous. It has been reported that cattle have been poisoned from drinking water into which seed pods have fallen.
Steve Christman 8/17/02; updated 1/29/04, 7/6/09, 5/3/12