General: Kentucky coffeetree is the only member of the genus Gymnocladus native to North America. The word gymnocladus comes from the Greek for naked branch, referring to the few stout twigs, which are conspicuous year round. The word dioicus relates to dioecious, meaning there are male and female trees. The tree lies dormant for about 6 months of the year, thus the name Dead Tree or Stump Tree.
Although a member of the legume family (Fabaceae), Kentucky coffeetree is not a nitrogen “fixer”. It is a medium to large, round-barked, native deciduous tree reaching heights of 18 to 30-m with a spread of 12 to 15-m. In open areas, the tree produces an open, rounded crown, but in native woods it grows to 23-m with few branches. Large specimen trees, such as Georgia’s champion tree stands 39.6-m tall in Pickens County, are uncommon. (The National Registry of Big Trees reports a specimen Kentucky coffeetree from Lake Co., Ohio, standing at 25-m with a spread of 23.5-m and a circumference of 5.2-m at DBH). Kentucky coffeetree’s short trunk, 0.3 to 0.8-m in diameter, divides into several large branches that end in contorted, stout twigs. Its unique, thick, dark bark is gray to grayish-brown, often marked with deep, irregular furrows and plates that curl at their sides.
The alternate, bipinnately compound leaves are the largest of any native species, measuring from 0.3 to 0.9-m in length by 4.6 to 6.1-dm in width, arranged in feather-fashion in 5 to 9 pairs of pinnae, the lowest are reduced to simple leaflets. Typically the leaves consist of six to 14 entire; more or less ovate (almond shaped) leaflets, 5 to 8-cm long, acute, rounded or cuneate at the base, pubescent beneath when young, short petioled, and swollen at the base. Leaves emerge late in the spring with a striking pink-bronze color, turning to a dark bluish-green above in summer. Fall color is often a golden yellow, but the leaves drop early.
Winter buds are small, reddish, and often placed above one another in close formation (superposed). Terminal buds are absent. The buds are small, downy, almost entirely imbedded in twigs, and surrounded by a hairy ring of bark.
The stout twigs are light brown to greenish-brown with whitish patches, somewhat zigzag or wavy, large heart shaped leaf scar, with a wide salmon-pink to brown colored pith.
Flowering and Fruiting: The greenish-white dioecious or polygamo-dioecious, inconspicous flowers appear in May and June, after the leaves, and are borne in terminal racemose clusters. The fruit is a tardily dehiscent, flat, thick, woody legume that ripens in September or October and usually persists unopened on the tree until late winter or early spring. The dark brown or red brown pod is 15 to 25-cm long, 2.5 to 5-cm wide, and usually contains 4 to 8 olive-green or dark brown to almost black seed separated by a mass of brown pulp.
Wood Characteristics: The wood is of heavy density (specific gravity of 0.53 green, 0.60 dry) with a coarse, straight grain. Its sapwood is narrow and yellowish white and the heartwood is light red to red or reddish brown. It is without characteristic odor or taste. Growth rings are conspicuously ring porous, resembling ash, honeylocust (Gleditsia triacanthos L.) or sassafras [Sassafras albidum (Nutt.) Nees.]. The wood is frequently confused with that of honey locust. It must be dried carefully due to a tendency to split. It is medium strong and has good to excellent working characteristics. Occasionally, it will show considerable ring shake, but is an attractive wood for home workshops. The wood finishes to a smooth surface and “polishes superbly”. It makes beautiful paneling which weathers to a light chocolate brown. When dry, the wood is stable and machines well.
Table 1. Fuel wood facts for Kentucky coffeetree.
*140,000 BTU per gallon of fuel oil.
Table 2. Kentucky coffeetree firewood quality ratings for five factors.
Ease of Splitting
Distribution: Kentucky coffeetree is uncommon in its native habitat. It can only be found in small colonies in temperate forests. The natural range extends from New York and Pennsylvania west to Minnesota, southward to Oklahoma, and east to Kentucky and Tennessee (Schopmeyer, 1974). The species is also found in the Dakotas, Texas, Georgia, and the Carolinas (PLANTS Database); naturalized in Alabama, West Virginia, Virginia, and Delaware (Steyermark, 1975). It is believed to have been introduced into some areas by Native Americans.
For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.
Habitat: Kentucky coffeetree grows in moist soils in bottom-land woods or rocky open wooded hillsides with other hardwood trees. It is commonly found on limestone soils and seldom found on unglaciated sites. The tree occurs sometimes in small colonies of rather widely separated individuals resulting from root suckers. Kentucky coffeetree can be found growing in association with sweetgum, tupelo, oaks, and hickories, also black walnut, basswood, elm, and pawpaw in temperate forests.
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