Kentucky coffee tree

not listed

N5? - Secure

SNR - Unranked

Special Concern

Kentucky coffee tree is a medium-sized, moderate-growing, deciduous tree that rises on a single trunk from a fibrous root system. In Minnesota mature trees are usually 50′ to 70′ tall and up to 24″ in diameter at breast height, though large individuals can reach over 80′ in height and 29″ in diameter. It is moderately long-lived, often lasting 75 years, though healthy individuals on favorable sites may survive 100 to 150 years. It spreads by root suckering, often forming interconnected colonies. Unlike most plants in the Pea (Fabaceae) family, the roots do not have nodules.

When growing in open areas the trunk is short, straight, and stout. It usually splits into three or four stout, ascending, principal branches about 10′ to 15′ above the ground. The crown is rounded and open. The branches are coarse, crooked, and widely spreading or weakly ascending. In forested areas the trunk is longer, the crown is narrow and pyramidal, and there are fewer, shorter branches.

The bark on young trees is light brown and smooth. It quickly breaks into conspicuous, large, flaky scales. On mature trees the bark is silvery gray, often tinged reddish, thick, and shallowly grooved, with scaly ridges that curl outward at the edges. On older trees the bark is dark gray and thick with shallow fissures and flat ridges.

The twigs are widely spaced and very stout. They are not noticeably zigzag. They are grayish-brown with whitish patches, hairless, and covered with scattered orange or pale dots (lenticels). The pith is large. homogeneous (not spongy), and orangish-red. The leaf scars are large, broad, and more or less heart-shaped. They have 3 or 5 large bundle scars.

The tip of the twigs are tapered to a blunt point and there are no terminal buds. Lateral buds are small, inconspicuous, ¼″ to ⅜″ long, and bronze. They appear in groups of 2 or 3 above the leaf scars. They are deeply sunken in raised craters that are filled with silky hairs.

The leaves appear in mid-spring before the flowers. They are the largest leaves of any tree in Minnesota. They are also the latest to appear in the spring and one of the first to drop in autumn. They are deciduous, alternate, 12″ to 36″ long, up to 24″ wide, and bipinnately compound with 40 to 100 leaflets. They are on stout, 4″ to 8″ long, hairless leaf stalks. They are pinnately divided into 4 to 7 primary divisions (pinnae), each with 4 to 6 pairs of leaflets. The lowest pair of pinnae are sometimes replaced with a pair of leaflets.

The leaflets are alternate, egg-shaped to broadly elliptic, ¾″ to 3½″ long, and ⅝″ to 2″ wide. They are usually rounded, sometimes broadly angled, at the base, and taper to a point at the tip, usually with straight sides along the tip, sometimes concave very near the tip. The upper surface is medium or dark green and hairless. The lower surface is pale green and finely hairy, at least along the veins. The margins are untoothed and have an inconspicuous fringe of short hairs. In early autumn the leaves turn yellowish-gold before dropping.

Male and female flowers are usually borne on the separate trees. Sometimes a tree with flowers of one gender will have some inflorescences with both flowers of that gender and bisexual (perfect) flowers. They appear when the leaves are unfolded in late May to late June. The inflorescence is a 2¾″ to 8″ long, ascending or spreading, unbranched array (raceme) of 18 to 50 flowers at the end of a short branch.

The flowers are about ¾″ long and are borne on ⅜″ to 1⅜″ long stalks. They have 5 sepals, 5 petals, 10 stamens, and 1 style. The sepals (calyx) are petal-like, greenish-white, linear, and ¼″ to ⅜″ long, shorter and narrower than the petals. They are moderately to densely hairy. The petals are greenish-white, narrowly oblong, and 5 ⁄16″ to 7 ⁄16″long. They are densely covered with woolly hairs. The stamens are two alternating series, one long and one short, with hairy filaments and yellow anthers. The style is short.

The fruit is a 3″ to 6″ long, ¾″ to 2″ wide, ⅜″ to ⅝″ thick, leathery, more or less oblong, flattened, straight or curved pod with 1 to 7 seeds. The pod is yellowish and velvety-hairy at first, later turning turn brown woody. The fruit ripens in Autumn and remains on the tree through the winter. The seeds are ⅝″ to ¾″ long and embedded in a green jelly-like pulp.

50′ to 70′

The champion Kentucky coffee tree in Minnesota is on public property near Owatonna, in Steele County. In 2009 it was measured at 68′ tall and 138″ in circumference (44″ in diameter).

greenish-white

Moist to moderately moist. River terraces above the flood plain. Full sun. Not shade tolerant. Well drained soil.

Late May to late June

The large fruit pods of Kentucky coffee tree are probably an adaptation to large mammals of the Pleistocene epoch. Horses, giant sloths, mastodons, and mammoths were present on the North American continent for millions of years. They probably ate the pods and dispersed the seeds in their scat. They disappeared in the Late Pleistocene extinction event, 20,000 to 10,000 years ago, when all large mammals (over 2,200 pounds) in North America went extinct.

Kentucky coffee tree is relatively disease and pest resistant

Sources

2, 3, 4, 5, 6, 7, 8, 24, 28, 29, 30.

Native to Wisconsin, Iowa, and South Dakota

Uncommon or rare

Kentucky coffeetree flower, Freeborn Co., Minn., June 2017

Old growth Kentucky coffee tree stand, including a long dead fallen giant, west of Faribault, MN, October 2016

Kentucky coffee tree in Owatonna, MN in July 2016

Location: Freeborn Co., MN

Kentucky coffeetree flower

Location: West of Faribault, MN

Old growth Kentucky coffee tree stand, including a long dead fallen giant

Location: Owatonna, MN