Wednesday, July 17, 2013

Kentucky Coffeetree

While at the University of Minnesota Landscape Arboretum, Erika and I spied one of our favorite plants, the Kentucky Coffeetree. The tree’s natural range covers the northern Midwest—Arkansas to southern Minnesota, Wisconsin, Michigan, and New York. Wild coffeetrees are over-harvested and declining (USDA). Another problem is that seeds germinate poorly—their shells are hard and not cached by squirrels. On hypothesis is that coffeetrees used to be germinated by mastodons, whose extinction proved problematic for the tree. This gem is from Wikipedia. The species is occasionally planted by landscapers—they make excellent shade trees, but they are messy when they shed their leaves and seedpods. The trees are, however, fascinating because of their huge, double-compound leaves. In the photograph, one of these leaves arches over the branch with the seed pods.  The “leaves” are actually leaflets. The whole leaf begins at the main branch to the left of the seedpods.

I always knew that coffeetrees owe their name to English colonialists who used the seedpods to substitute for coffee. I did not know that uncooked seeds, pods and leaves are poisonous. The USDA warns, "Clinical signs include rapid onset (within 1 hour) of intense gastrointestinal irritation, profuse diarrhea and straining, vomiting, hypertension, bradycardia, respiratory depression, muscle paralysis, and convulsions. Animals often display depression. Death usually occurs within a day after clinical signs appear.” Exactly which substance make the trees poisonous is unclear.

Boiling destroys the toxin, but there is at least one report of someone dying from consuming parts of a coffeetree. Nevertheless, Native Americans used coffeetrees for a number of remedies. The wood treated insanity, fever, and headaches. Others used it as an appetizer, tonic and laxative. Uncooked beans were thrown into streams to kill fish. Cattle may have died from drinking from pools containing leaves and seeds.

No comments:

Post a Comment