Badger Tracks

By Anita Carpenter

Coffee anyone?

What native tree found in extreme southern Wisconsin, could boast that it has one of the largest, if not the largest leaf, of any deciduous tree in the United States? This rare, medium to large-sized tree is called the Kentucky coffeetree.

At first glance, Kentucky coffeetrees might resemble any other tree with its 2", smooth-edged, oval leaves. However, each individual "leaf" is not what it appears to be because each leaf is actually one small part of a much larger leaf. Let's take a closer look.

When a Kentucky coffeetree produces a new leaf, it sprouts a midrib that has 5 to 9 slender branches attached alternately along the midrib. Each of these branches then sprouts up to 16 or so of the 2" leaflets. 

Consequently, one entire leaf may display up to 100 of the 2" leaflets and measure from 1 to 3 feet long. Because the entire leaf has branched twice, botanists identify this leaf as being twice compound. Not many plants with twice compound leaves are found in nature. This uncommon leaf silhouette is just one of the unusual and interesting features of this tree.

Another interesting feature is the presence of separate male and female trees. How does one tell the trees apart? After the leaves sprout in late spring, look for tiny, greenish-white flowers which can be easily overlooked. (I can attest to that!). Flowers hang in small clusters with male clusters (on male trees) being shorter than female clusters (on female trees). Insects pollinate the flowers.

Fruits develop on female trees as thick, reddish-brown, leathery pods which, when mature, measure about 1-1/2" wide and 5 to 10 inches long. Each pod contains a few large, brown, hard-shelled, slightly flattened, 1/2" seeds nestled in a thick, sticky pulp. Mature pods remain closed on the trees through winter which provides an easy clue for tree identification. The closed pods drop in spring, dry out and open.

The Kentucky coffeetree is considered rare throughout its mid-continent range. Its rarity may be due to the challenges it faces with seed dispersal and successful germination. Nothing eats the seeds (although I've seen crows hammering on the pods and seeds), therefore no critters help the tree spread its seeds. Also, each seed has a thick, hard shell that must be scarified. This means something must split, scrape or somehow damage the shell to expose the seed thus leading to possible germination.

However, the location of coffeetrees may aid seed dispersal. These trees are often found in rich, bottomland habitats often associated with water. Nearby streams and floods may carry the pods and seeds to new suitable areas for germination.

How did the tree get its name? Historical records indicate native people and early settlers roasted and ground the seeds, then used the powder to make coffee. It's suggested that early Kentucky settlers may have coined the name. It should be noted that the pods and seeds are poisonous but prolonged roasting detoxifies the seeds. PLEASE DO NOT TRY THIS!  Besides, this coffee is non-caffeinated!

Anthropological studies of native villages often documented the presence of Kentucky coffeetrees. Evidence shows that the villagers used the seeds in jewelry, in ceremonies, and for games of chance. These trees were most likely planted.

Kentucky coffeetree leaves turn yellow and drop early in autumn. New leaves sprout about 6 to 7 months later in late spring. Its scientific name, Gymnocladus dioicus refers to this unusually long leafless period. Gymno means naked and cladus means branch. Dioicus refers to separate male and female trees.

If you would like to see these rare trees, walk the Wiouwash Trail along the Fox River on the UWO campus. Just north of the Wellness Center you will find 5 trees (4 female trees with pods and 1 podless male). They are planted in a row of trees on the inside of the trail - not the riverside. Look at their graceful silhouettes with curvy and angular branches and rough, scaly fissured bark.

This is one of my favorite trees which I visit daily on my morning walk.   

April-May-June 2024 Newsletter