Kentucky Coffeetree

Basic Information

Tree ID:

157

Family:

Legumes

Genus and species:

Gymnocladus dioicus

Description:

The Kentucky Coffeetree is a slow to medium-growing species that is native to the midwest; it was Kentucky's state tree for nearly 20 years, hence providing the first part of this organism's name. While the second part of this tree's name (coffee) may seem inviting to taste this plant, it is important not to eat this plant raw, as the seeds and pods are poisonous to humans because they contain cytosine. However, upon roasting them, one can use the leaves, seeds, and pulp of the Kentucky Coffeetree to make beverages similar to coffee. This tree is remarkable in its toughness and adaptability; it can survive both droughts and floods, as well as high levels of air pollution. The Kentucky Coffeetree makes a great ornamental tree (as seen on Yale's campus) due to its unique ascending branching structure, which gives the plant a crown-like appearance. Students can look forward to this striking view as May and June approach, as the Kentucky Coffeetree is known to bloom in late spring. On the topic of blooming, this species is deciduous; its leaves emerge in a beautiful bronze-pink shade and progress to dark green over time, then as fall comes, the leaves turn yellow and brown before falling from the tree.

Surveyors:

Mikayla Barber, Sophia De Oliveira, Jamarc Simon

Location

Area:

Prospect and Sachem

Collected Data

Tree shape:

oval, rounded

Date of tree entry:

02/08/2023

Height:

4.70 m

Diameter at breast height:

0.23 m

Bark

The bark of the Kentucky coffeetree is rough and scaly with deep zig-zag fissures running up the length of the tree trunk. On the outside, the bark has an ash-gray/green color but the inside fissures are a light brown clay color. As the tree grows, its bark will start to look more and more like it is peeling. Due to the wood's relative rarity, it has not had a significant impact in the commercial industry but in some cases, has been used for fuel, furniture, cabinetry, and fence posts.

Twigs & branches

The fully developed twigs of the Kentucky Coffeetree are a dark reddish-brown or greenish-brown color and are covered with lenticles (pores). The twigs' thin bark peels away to reveal a pale pinkish color underneath. There is no terminal bud, and the lateral buds on the branches have a bronze color. Lateral buds usually range from 6-9 mm in length and have a number of scales that are coated in black, silky hairs. In the wintertime, it is very easy to identify a Kentucky coffeetree because of its reddish-brown twigs and scaly gray-brown wrinkled bark. The genus "Gymnocladus" actually means "naked branch" which refers to the Kentucky coffeetree's conspicuous stout twigs.

Foilage

Kentucky coffeetrees have characteristic pinnate compound leaves that are composed of about 70 individual leaflets. The leaflets are usually around 5 cm long and grow alternately on reddish stems. The fluffy, deep-green leaves that can be seen on mature trees can range in length from 0.3 to 1 meters. The leaves are very slow to appear and don't emerge until late spring (mid-late May), and in the fall, they turn a brilliant golden yellow. There are four to six paired "branches" of leaflets on each leaf, and every "branch" has 8–16 leaflets. Because this tree doesn't start growing new leaves until late May, no leaves were observed while surveying the tree. A image obtained from online shows the leaves.

Reproductive Structures

The flowers of the Kentucky Coffeetree grow in clusters, are dicots, and are pollinated by insects. They are dioecious plants which means the male and female flowers grow on separate trees. Branched clusters of male flowers can be up to 10 cm long, while unbranched clusters of female flowers are anywhere from 20 to 30 cm long. Flowers have five petals, are hairy, greenish-white, and measure between 2 and 3 cm. The appearance of male and female flowers is similar. The flowers blossom in late May, around the same time the leaves start to grow, and give off a rose-like smell.

Fruit

The Kentucky Coffeetree produces fruit that come in thick, hard, leathery pods that are about 12 - 20 cm long. At the beginning of the summer, the pods are green and then change to brown in October once they are fully developed. On the inside, each pod contains many flattened brown seeds that are about 2 cm long and are covered in a sticky sap substance. During winter seasons, it is common to see some pods still attached to the tree. Its fruit type is legume because it is a dry, multiple-seeded fruit that grows from a single flower with a single-celled ovary that breaks apart along two seams at maturity and is in a long pod.

Seasons

Kentucky Coffeetree in the Winter (Taken 2/8/23)
Kentucky Coffeetree in the Winter (Taken 2/13/23)
Kentucky Coffeetree in the Winter (Taken 2/20/23)
Kentucky Coffeetree in the Winter (Taken 2/27/23)
Kentucky Coffeetree in the Winter (Taken 3/6/23)
Kentucky Coffeetree in the Spring (Taken 3/27/23)
Kentucky Coffeetree in the Spring (Taken 4/3/23)
Kentucky Coffeetree in the Spring (Taken 4/10/23)
Kentucky Coffeetree in the Spring (Taken 4/17/23)
Kentucky Coffeetree in the Spring (Taken 4/24/23)

Research

Natural range of distribution:

Habitat:

The Kentucky coffeetree is native to southeastern Canada and the central and eastern United States. Though the Kentucky coffeetree tolerates a wide variety of habitats, it prefers rich, moist soils common in floodplains, terraces, ravines, coves, and lower slopes.

Origin, history, and uses:

Historical evidence suggests that the Kentucky coffetree was introduced into Kentucky by Native Americans, who used its pulp to treat cases of insanity. Additionally, Native Americans and early settlers would use the seeds of the Kentucky coffeetree to create a coffee-like beverage, hence the tree’s name. Today, the Kentucky coffeetree, specifically its strong and heavy wood, is used to create furniture, railway sleepers, bridge timbers, and fence posts. Due to its remarkable resistance to pollution and drought, the Kentucky coffeetree is also used as an ornamental tree in many parks, golf courses, and other large urban areas.

Phenology:

The Kentucky coffeetree is without leaves for the majority of the year. Its leaves emerge in late spring with a bright green color and matures to a yellow-brown color by early fall when they eventually drop. Greenish-white flowers appear at the branch tips in late spring/early summer and large purplish-brown or reddish-brown seed pods grow on female trees in the fall.

References:

The Kentucky Coffeetree: An evolutionary anachronism? - Carleton College Cowling Arboretum. Carleton. Retrieved April 21, 2023, from https://www.carleton.edu/arboretum/news/the-kentucky-coffeetree-an-evolu….

Gymnocladus dioicus. Gymnocladus dioicus (Coffeetree, Kentucky Coffeetree, Kentucky Coffee Tree) | North Carolina Extension Gardener Plant Toolbox. (n.d.). Retrieved April 21, 2023, from https://plants.ces.ncsu.edu/plants/gymnocladus-dioicus/

Gymnocladus dioicus (Kentucky Coffee Tree). Lurie Garden. (n.d.). Retrieved April 21, 2023, from https://www.luriegarden.org/plants/kentucky-coffee-tree/.

Janzen, D. H. (1976). Effect of Defoliation on Fruit-bearing Branches of the Kentucky Coffee Tree, Gymnoclaudus dioicus (Leguminosae). The American Midland Naturalist, 95(2), 474–478. https://doi.org/10.2307/2424414

Halisteinmann. (2013, July 10). Plant of the day: The Kentucky coffeetree. Sewanee Herbarium. Retrieved April 21, 2023, from https://sewaneeherbarium.wordpress.com/2013/07/10/plant-of-the-day-the-k…

Kentucky coffeetree. Kentucky Coffeetree | Arnold Arboretum. (n.d.). Retrieved April 21, 2023, from https://arboretum.harvard.edu/plant-bios/kentucky-coffeetree/.

Kentucky coffeetree: gymnocladus dioicus. Kentucky Coffeetree Tree on the Tree Guide at arborday.org. (n.d.). Retrieved April 21, 2023, from https://www.arborday.org/trees/treeguide/TreeDetail.cfm?ItemID=819.

Smith, Welby. “Gymnocladus Dioica : Kentucky Coffee Tree: Rare Species Guide.” Minnesota Department of Natural Resources, 2 July 2022, https://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&select…

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