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Plants in the Eloise Butler Wildflower Garden


The Kentucky Coffeetree

by Gary Bebeau


Coffeetree in fall
Kentucky Coffeetree in Spring with bare branches except for the prior years seedpods still attached to branch tips.

Eloise Butler wrote in 1914 “In winter, a more intimate acquaintance can be made with deciduous trees. For it is only after the leaves have fallen that the architecture of trees can be clearly discerned. Every species has a different form. No individual, ever is exactly like another.” (1)

So, what is that dead tree over there? Rough bark, stubby sparse branches, bare twigs - it appears deceased except for those funny pouches on the end of some branches. You are looking at a Kentucky Coffeetree in the winter. Those ‘pouches’ are the past season’s seedpods, the branches are stubby and sparse by design as they have to support the largest leaves of any native North American deciduous tree. Bare twigs - the tree hides its buds until just before the leaves pop out. It’s scientific name is Gymnocladus dioicus. The first part is from two Greek words meaning ‘naked’ and ‘branch’ - the appearance when not in leaf. The second word, dioicus, meaning ‘separate houses’ is used when the flowers of the tree are of one sex only and trees of the male sex must be close by for the female flowers to be pollinated and produce the seed pods.

Coffeetree in spring
Kentucky Coffeetree in late Spring fully leafed-out.

Kentucky Coffeetree grows up to 80 feet in height with a rounded to open crown depending of how much space it has. As trees go, this one has attractive, quite striking, flowers with a purple calyx, whitish petals, yellows on the reproductive parts - its in the Pea Family (Fabaceae) where you usually find colorful attractive flowers.

Eloise Butler liked it but it was not found in her Garden as it is native to the counties south of the metro area, so she obtained some selections from the Park Board nursery, which at the time, was located in Glenwood Park, of which her Garden was a corner of. [Now Theodore Wirth Park]. Eloise’s successor, Martha Crone, really liked the tree; she planted 36 of them in 1934 and more in 1949. It is without doubt that those large ones on Geranium Path and Violet Way in the Garden are those early trees.

Today, the Coffeetree is so rare in the wild that it is listed on the Minnesota DNR’s ‘Special Concern’ List. It is also becoming rare in other parts of North America. Fortunately, it is planted in many public spaces. I see it frequently in a number of public parks and the Minnesota Landscape Arboretum has a number of them gracing the hillside of the new sculpture garden - but none so large as those in the Garden.

flowers
The female flowers of the Kentucky Coffeetree

A Park Board official wrote in 1975 “Over the last century the Park Board has planted a number of these interesting trees throughout the city. Most parks have at least one of them. The largest of these are two Kentucky Coffeetrees growing on either side of Minnehaha Creek just upstream from the point where Lake Nokomis flows into the creek.” (2)

Now to the matter of that name - Coffeetree. It was not a good tasting beverage. Francois Michaux said it best: "The name of Coffee Tree was given to this vegetable by the early emigrants to Kentucky and Tennessee, who hoped to find in its seeds a substitute for coffee; but the small number of persons who made the experiment abandoned it, as soon as it became easy to obtain from the seaports the coffee of the West Indies.” (3) Michaux also noted that those early emigrants sent the tree to France in late 1700’s where it thrived in and around Paris. Maybe their descendants are still there.


Below: The leaves are bi-pinnately compound, the largest leaves of any North American native species.

tree leaves
My Kentucky Coffeetree

All that is required to grow the tree is a seed, space and patience - especially the latter. Wait till Spring and find one of the seed pods that has overwintered on the tree or on the ground below the tree. The seeds will be ready to germinate. There are usually 4 to 6 seeds per pod embedded in a sticky pulp. Most critters avoid eating the seed as they contain a toxic alkaloid called cystisine, so its not hard to find pods. Find an open space where the tree has room to grow. The 3/4 inch seed, should be scarified and just-covered with soil, watered and put a little fence around it. I started mine in a small pot, which requires planting in the ground by Autumn or the root development will be hindered.

seeds
The dark seeds of Kentucky Coffeetree just beginning to sprout.

Now comes the patience part. Some say the tree is fast growing at first then it slows down; commentary perhaps from someone who never grew one. My tree has been in the ground six years now and it is six feet high. It looked nice when it had those large compound Summer leaves but after leaf-fall it was just a stick, that is, until year six when I saw near the top of the stick a short stub. Finally a branch! Yes, in year six several leaves developed on the stub and now it will begin to look like a real tree - sometime - as after leaf-fall I still have a stick, but with a stub near the top. I wonder what sex it is - will it be female and have fragrant flowers and maybe get pollinated from some male in a near-by park and make seeds? or will it be male and just have flowers? I will never know. Most deciduous trees require decades before flowering and bearing fruit. Maybe the next steward of my plot of land will find out - or the person after that - but hopefully the tree will survive and add another touch of interest to the landscape.



References:
(1) Annals of the Wildlife Reserve, 1914, unpublished.
(2) Mr. Gordon Morrison, Coordinator of Environment Education for the Minneapolis Park Board, The Fringed Gentian™, 1975
(3) Francois Michaux, The North American Sylva or A Description of the Forest Trees of the United States, Canada and Nova Scotia, Vol. 1, 1819.