KENTUCKY COFFEE TREE- Gymnocladus dioica
This member of the pea family (Fabaceae) can get 50’-60’ high and 30’-40’ wide, though most that I’ve seen in Colorado are under 45’. Nearly everybody thinks of this tree as interesting or picturesque.The branching is more open than most trees and the bark is gray to dark brown, rough and deeply ridged even on small branches. The leaves are bluish-green and somewhat tropical-looking being double compound, each one 18”-24” long and forked with small leaflets alternating on the stem. Fall color is yellow. As the species name implies, this tree is dioecious, having the male and female flowers on separate trees. The flowers are greenish-white, supposedly fragrant and not conspicuous. On the female trees, tough, leathery seed pods follow that are 4”-6” long and 1 1/4”-2” wide. These hang on after the leaves fall and into the winter. There has been mention of these pods being messy, but I haven’t seen large numbers of them. Inside the pods are large, hard, dark-brown seeds in a sweet, sticky pulp. It is commonly reported that early settlers used these seeds as a coffee substitute. What is not well known is that these seeds are poisonous. Michael Dirr mentions that cattle have been poisoned by drinking from pools into which the seed pods had fallen. So it is possible that it could poison fish also. It is speculated that roasting may remove the toxicity. I wouldn’t be in a hurry to try it.
This tree is native to Kentucky, New York, Pennsylvania and Nebraska and is hardy to at least zone 4. In the wild it grows on rich river-bottom land and in fertile ravines. However one of the great attributes of Kentucky Coffee Tree is that it is very tolerant of a wide range of cultural conditions. It enjoys rich, moist soils and probably compost and ample water would be good to help get it established, but after that it is tolerant of drought, alkalinity, salt, high wind and pollution. It has a deep root system, strong wood, it leafs out late avoiding snow breakage, and has no serious pests or diseases. It is very slow-growing and probably is not the best shade tree. However for creating filtered shade where grass and shrubs can grow and for sculptural form, it is a good choice. Possibly the depth of shade and volume of pods are relative to the amount of watering