(The misnomer “Poison-Oak” is applied sometimes to this species, although in Florida that name is probably best reserved for the close relative Toxicodendron pubescens and relatives in the Western U.S.)
Anacardiaceae, the Cashew Family, many of which can cause dermatitis
Continuing our month-of-Fridays probe into the botany of the Kiplinger Nature Preserve today in perfect weather, John and I found the plant most interestingly in bloom to be poison ivy. Too bad it is nasty, because the species has a certain charm and fascinating natural history otherwise.
Poison Ivy is not “a” species, but rather the most mind-boggling complex of Mother Nature’s messy handiwork you can find. Anyone who wants to reduce botany to simplistic species and easy rules better first look at this perplexing tangle of variation ranging across much of Asia, North America, and parts of Tropical America, but neither Europe nor Africa. Different people can look into the complex and see different species, subspecies, varieties, and even different genera, with our well known eastern Poison Ivy more similar to the same species in Japan than it is to all the numerous variants in the rest of the U.S. and Mexico. The big ol’ mess was sorted out painstakingly by Michigan State University botanist William Gillis on the shoulders of predecessors. The late Dr. Gillis and I shared the distinction of our careers intersecting with the only botanist convicted of booking a hitman to murder his wife.
A good segue into Poison Ivy. The writing on P.I. as a poison are infinite, so to pick the weirdest aspect of that history I know of, as documented by Gillis, hereyago: indigenous men in California used the irritating plants to oppress women. When the men wanted to meet and keep the women apart, one guy would strip naked, be body painted, and run around all crazy threatening the women with wet poison ivy branches suspended around his head. Who would volunteer for that job? The hazards are numerous. A better use of the plant, despite the itch, was in the Netherlands to reinforce dikes. Worked better than a little boy sticking his finger in the leak.
Would you believe Poison Ivy has a role in ornamental horticulture? It develops red fall color and contributes to the subtle autumn hues in South Florida. It has served in that capacity cultivated in gardens in climates where fall color is otherwise deficient.
Poison Ivy has the ability to resurrect dead trees. The vine climbs hugging the defunct trunk, and way up high decides to branch out like the original limbs on the tree. From the distance such a tree looks like a very odd species. Here is the vine covering a dead tree in flames. CLICK
We’ve been trying to catch it in bloom, so today was a minor triumph. The flowers are separately male or female, on distinct plants. In some locales, the male plants have foliage differing from the females, a weird occurrence. Why?
The flowers draw bees, and Poison Ivy honey is not unheard of. No thank you. The blossoms mature into little “berries” which are not berries; they are related to and resemble mini-mangoes: lopsided, flattened, and with a “stone.” As the fruits age, the outer layer separates from the stone leaving a hollow space, and the outer layer can crack open along lines.
To wrap up, one more oddity. Commonly allergic reactions come from proteins. Poison Ivy causes a horrid allergic reaction yet its toxin is not a protein. Oh however can that be? Apparently the plant’s poison, urushiol, binds and alters proteins in human skin, and then those altered self-protein complexes kick off an allergy, sort of a vine-mediated auto-immune disorder. The itchy oil is almost a varnish. It can collect in sufficient quantities on the leaves to dry into a black spotty paintjob, a skull and crossbones reminder. Fact is, the Chinese Lacquer Tree is itself likewise a species of Toxicodendron.