The Naked Branch

I'm not much of a tree person. Although I appreciate many things about them, I am unable to retain many identification cues in my brain, regardless of how many times someone tells me this specific tree is a Black Cherry or that one with the warty bark is a Hackberry.

I like my trees obvious. My favorites are those with comically unmistakable leaves: Catalpas, with their huge, pale green hearts, or Tulip Trees with their vaguely tulip-shaped leaves. Honey Locusts are pretty and easy, with delicate-looking compound leaflets and, in wild varieties, wicked-looking clusters of thorns adorning the trunk.

The naked branches of
the Kentucky Coffee
Tree in winter.

But there is one tree that even I found easy to identify--in winter! There are a few of them planted along the Greenway trail, just a bit north of the Sycamore Apartments: the Kentucky Coffee Tree (Gymnocladus dioicus). The genus name gives a hint as to why it is so distinctive even without its leafy adornments: Gymnocladus means "naked branch" and, when you see a bare Kentucky Coffee Tree, the branches do look rather empty, lacking all the smaller branching twigs you see on many other trees.

They also have distinctive leathery seed pods that dangle from the upper limbs through the winter. About the size of my palm or larger, they are shorter and wider than the pods of the related Honey Locust.  The seeds can be roasted and ground to make a coffee-like drink (hence its common name); however the seeds and pods are toxic when raw so caution is required for any adventurous souls tempted to try this rustic coffee substitute.

Seed pods, looking dramatic.

The leaves themselves resemble those of Honey Locust in that they are compound, consisting of a many small leaflets and sub-leaflets. The leaves themselves are huge, though at a glance they don't appear so since we generally register only the small sub-leaflets as "leaves." Rather, each complete "leaf" can be up to three feet long, with multiple leaflets branching off and each leaflet containing multiple sub-leaflets.

• This illustration at the Arbor Day Foundation's website shows two complete leaves and two seed pods.

The flowers are less spectacular, though still somewhat flashy and interesting if you happen to catch them in the spring.

A cluster of flowers, or panicle.

The seed pods of the Kentucky Coffee Tree are an interesting anachronism. The seeds and pods themselves are toxic and have been known to kill livestock; they are too large to be eaten by birds and too tough to be nibbled by smaller animals (leaving aside the toxic bit)--so why does the tree expend the effort to make these large pods for their seeds, and why is the pulp surrounding the seeds sweet to taste if the seeds themselves are poisonous?

It has been speculated that some critters were big enough and tough enough to consume the pods without suffering ill effects from the toxin, and allow the seeds to pass through (so to speak) and be dispersed throughout the landscape: prehistoric mammoths and mastodons. We may be seeing in our little Kentucky Coffee Tree on the Greenway the remnants of a completely different ecosystem that has managed to hang on in spite of losing its evolutionary partner.

• Read more about "Evolutionary Anachronism" in trees.