Plant of the Month - January, 2008

ARBORETUM PLANT OF THE MONTH FEATURE

by Mike Wolf
Bickelhaupt Arboretum
Roots Board Member

Gymnocladus dioicus
Kentucky Coffeetree

"To know her is to love her." Those are the first words Michael Dirr, a noted American horticulturalist, uses to describe this wonderful tree.

It is native to this area. Capable of taking anything nature or people can throw at it. As a consequence, it is easy to grow. My two trees started as seeds collected from foot-long, dark-brown pods found on the Detroit Zoo grounds. A friend planted them with a dozen or so others in his suburban Detroit back yard in a small, unused corner of his garden. He started them to transplant to his farm in northern Michigan. Every seed germinated and they grew about a foot a year.

When I stopped by my friend's house in October 1995 to said good-bye just before my journey to Clinton, Iowa, he dug up two four-foot trees bare root. Since the Kentucky Coffeetree has the largest compound leaf in North America where the leaf substitutes for branches, young trees have very few branches. In my case, both were just poles with a foot-long root that looked like a carrot. He tied the two pole-like trees to the van top. They rode the whole way to Iowa without any protection. When I arrived here in Clinton, I just poked two holes in the ground, stuck them in like a stake and forgot them.

Over the winter, deer ate 6" to 8" of the soft tops off, and then rubbed them to the ground. When the ground thawed, I straightened them up, not wanting to give up for my friend's sake. Late spring saw new growth start at a point just below where the deer had torn the bark. Amazingly, both grew new leaders and a small, but impressive, five-foot canopy. That fall I protected them with four-foot high wire fence. The deer reached over and chewed all the previous season's growth right off.

Surely, that was it. But, like clockwork, they came back. I raised the fence a foot the following year, and the deer left them alone. Since then, they have grown to reach a height of 20 feet forming a nice 15-foot wide crown.

The tree has a very pleasing rugged look. Its branch structure is uniform and muscular with an extremely ridged and rough-looking bark providing additional interest after its leaves fall.

As noted earlier, the tree has an extremely large compound leaf structure (a two-foot long main stem sporting 12 to 16 stems, each a foot long, growing perpendicular to the main stem holding 12 to 16 leaves, each approximately 1 to 3 inches long), which acts like branches in the summer, but fall as leaves in autumn. Due to this leaf structure, it has fewer branches to break in heavy winds and inclement weather. It is impervious to ice storms; very comforting to know this time of year.

The Kentucky Coffeetree grows in any type of soil: from wet to dry, from clay to sand, and from acidic to alkaline. It has no known diseases. It is not vulnerable to or attacked by pests, such as the Japanese beetle or emerald ash borer. It is comfortable in the middle of a sun-baked parking lot or a cool riverbank.

The Kentucky Coffeetree grows into a magnificent hardwood shade tree. Its rounded crown reaches a height of 60 to 70 feet high and stretches out 40 to 50 feet.

In addition to giving this tree the room to roam the sky, you do not want to plant anything underneath it either. It does well with grass, but will sport new trees through any planting underneath it. Just remember, give it space ground up and it will reward you with problem-free shade and beauty.

Also, the Kentucky Coffeetree produces both male and female trees. Since my trees grew from seed, I won't know what sex they are until they mature. Female trees produce large foot-long seed pods that are three inches wide and one-half inch thick. Each pod holds dozens of dark brown seeds the size and color of a coffee bean. When dry, the pods make great music instruments, such as shakers. Native American children used the seeds to play games, causing many trees to grow near tribal villages.

Most people probably would prefer to avoid the mess and work cleaning up these large pods. Fortunately, nurseries sell the pod-free male trees, which are propagated from root cuttings of known male trees. The fruitless male tree flowers, yet leaves no messy pods to clean up.

This underused tree is well worth considering for disease-free, insect-resistant growth for any soil, location or weather condition you can imagine. Nothing like a worry-free tree you can count on standing for years of care-free growth.


About the author: Mike Wolf grew up on a farm where he had a several acre garden, a large yard and a nearby river. He spent hours helping his parents and extended family with growing, harvesting and canning the many vegetables and fruits on the farm. The river was a constant place of exploration, adventure and imagination. Trees and plants continue to inspire him. Mike is a valued Roots Advisory Board member. The Bickelhaupt Arboretum is fortunate to have him on the Roots Board.