Kentucky Coffeetree (Gymnocladus dioicus) -- easily recognized in summer by its huge compound leaves and in winter by its bold outline -- is present throughout much of Ohio, but is primarily found in the western half of the state, where the soils are more alkaline. Thick fruit pods containing large seeds (or beans) are found only on female trees, and often hang on during winter. Pioneers in Kentucky and elsewhere used the beans as a coffee substitute (hence the common name), and Native Americans roasted the beans for food.
A native of the Midwestern United States, the slow-growing Kentucky Coffeetree reaches 80 feet tall and 50 feet wide when found in the open, with an upright, irregular, and thin appearance in youth, becoming dense and symmetrical with age. As a member of the Bean Family, it is related to many other representative species, including Redbud, Honeylocust, Black Locust, and Wisteria, among others. The specific epithet of "dioicus" is sometimes alternatively spelled as "dioica"; in either case, it refers to the male and female nature of this species, termed "dioecious."
Planting Requirements - Kentucky Coffeetree prefers deep, moist, alkaline soils, but thrives almost anywhere it is planted, except for permanently wet soils. It is extremely tolerant to many stresses (including heat, drought, poor soils, compacted soils, high pH soils, occasional brief flooding, and air pollution), and has been extensively planted in parks along the East Coast, thus extending its geographic range. It grows in full sun to partial sun, and is found in zones 4 to 8.
Potential Problems - Kentucky Coffeetree offers no significant disease or pest problems, and should be more widely planted in open spaces that can afford its large size and beauty at maturity. Since it does not fruit at an early age, determination of gender may take a number of years, since the seedless males offer less of a cleanup problem due to the absence of fallen fruit pods and seeds. In youth, the appearance of this tree often lacks grace, especially in winter, with the little-branched winter outline being especially coarse (Gymnocladus translates as "naked branch").
Identifying Features - Kentucky Coffeetree
Kentucky Coffeetree has the largest leaves of any tree found in eastern North America, with each being up to three feet long and composed of many leaflets. The leaflets attach in alternate fashion to a rachilla, and several rachilla attach in opposite fashion to the central rachis. The rachis has a swollen base, and the entire bipinnately compound leaf is arranged in alternate fashion along the stout twig. The rachis leaves behind a huge leaf scar when it detaches from the stout stem in autumn or winter.
While the texture of Kentucky Coffeetree is extremely bold in winter, its numerous leaflets give it a medium-fine texture during summer. This tree is one of the last to leaf out in spring, when the new growth is often bronzed (reddish tinted). Furthermore, it often has some of its rachises hang on into late winter, creating additional cleanup in spring when found in urban landscapes. Fall color of the leaflets is usually a faded green or chartreuse (yellow-green) and not attractive.
Kentucky Coffeetree often goes unnoticed when in flower in late spring, because the floral petals are small and compete with the emerging bronzed foliage for attention. In the photo shown, the thicker male flower is tilted to the left, while the thinner female flower is angled to the right. The female flowers occur on female trees and may be up to a foot in length, while the male flowers on male trees are often shorter but found in greater abundance.
Female Kentucky Coffeetrees may bear fruit pods in great abundance, standing out as light green in the otherwise dark green to blue-green canopy of the tree in summer. Fruiting is often heavy every second or third year, and light in other years. The pods are thick and slowly change to light brown then dark brown in autumn, and may persist throughout winter and into the following spring. Each contains several round, hard, dark brown seeds once the pod is split open.
The stout, branchless twigs of Kentucky Coffeetree stand out starkly in winter outline and have huge leaf scars with one or two small lateral buds that are barely visible just above the leaf scars. Like its close relative Honeylocust, a terminal bud is absent from the ends of its twigs. With maturity, lower branches often become pendulous.
Part of the beauty of Kentucky Coffeetree in winter is the flares of bark that originate from its branches and upper trunk in winter. However, its lower trunk is much more subdued, having flattened ridges and shallow fissures that are shades of gray.