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Wednesday, 26 December 2007 00:00

A plant’s purpose

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There are more than 300,000 plant species in the world. Some are edible, some can be used for their medicinal properties, and many are poisonous. The latter category is defined by Nancy J. Turner and Adam F. Szczawinski in Common Poisonous Plants and Mushrooms of North America (Portland, Oregon: Timber Press, 1991) as “plants and parts of plants that contain potentially harmful substances in high enough concentrations to cause chemical injury if touched or swallowed.”

Many plants widely used for medicinal or food purposes can also be harmful when prepared in an improper fashion. For instance, pokeweed — from the tender sprouts of which a traditional spring potherb is often prepared — has caused abdominal cramps, diarrhea, and even convulsions and death. Although cooking in two waters eliminates most of the toxins, a real danger lies in just handling the stuff. It contains an active ingredient (mitogen) that can cause serious blood-cell abnormalities when absorbed through cuts and abrasions.

Like poisonous serpents, some plants developed toxic properties in order to protect themselves against predators. Besides insects, the major predators are herbivores: bison, deer, rabbits, mice, caterpillars, aphids, and any other critters — including humans — that devour plant matter above or below ground. Other “herbivore defenses” include spines (as with thistles), stinging hairs that detach in a predator’s skin like a bee’s stinger (nettles), thorns (as with the honey locust tree and Osage orange, which was used in the mid-West to fence out cattle before the invention of barbed wire), and leaves with spiny edges (as with holly).

In turn, numerous animals have evolved the ability to tolerate or detoxify plant defense compounds. Beavers, for instance, feed heavily on aspen bark or other plants that contain salicin, which negates the defense compounds devised by many of the other plants they eat. Insects and mammals generally prefer to feed upon leaves and shoots of plants, as they are tender, digestible, and contain the least concentrations of the defense compounds.

The Cherokees still harvest and cook a number of mushrooms each fall. But they learned early on — no doubt by trial and error — to avoid all of the species of Amanitas, a genus that does contain some choice edible species. Amanitas are one of those critical plant-gathering categories in which an identification mistake can mean death.

The destroying angel, a strikingly beautiful Amanita mushroom, has acquired a reputation as the deadliest member of the genus, but it’s the aptly named death cap that’s responsible for the most fatalities each year. As little as half a fresh death cap can be fatal to an adult. Children ingesting that amount have a mortality rate of 50 percent. A period of nausea and shock six to 24 hours after ingestion is followed by a four-day period of “false recovery,” after which death occurs within seven to 10 days due to liver, kidney, and heart failure.

We can’t discuss poisonous plants and their defenses without considering poison ivy. I used to joke about poison ivy until several years ago when I inadvertently chain-sawed a huge vine growing on a black locust tree I’d cut down for firewood. I got the juice all over myself in some very sensitive places. My attitude was immediately adjusted — no more poison ivy jokes. Before that incidents, I was pretty much immune, but these days even a casual encounter can bring on the itching and scratching.

The culprit is urushiol, a sap-like oil found in the roots, stems, leaves, flowers, and fruits of poison ivy that evolved as a chemical defense mechanism against browsing herbivores and, perhaps, insects. It’s so powerful that one part mixed with 60,000 parts olive oil is said to still cause infection.

The ancient Cherokees either rubbed on the beaten flesh of a crawfish or applied the juice from seven blossoms of jewelweed. The early white settlers applied crushed jewelweed stems and leaves. Other old-time antidotes included the use of boiled milkweed, a potentially powerful concoction comprised of buttermilk and gunpowder, a mixture of vinegar and salt, and a mixture of soap and wood ashes.

Many still swear by jewelweed, but the very best antidote, for me is one that I only discovered within recent years. That’s Dawn dish detergent. Something in that brand of detergent, which is also a degreaser, completely neutralizes the effects of urushiol on my skin. I apply the detergent liberally to the irritated area and let it dry. After just a few minutes there’s almost immediate relief. And after an hour or so the irritation is eradicated. Accordingly, a modern-day dish detergent has become my counter defense to another defense mechanism evolved eons ago by poison ivy.

George Ellison wrote the biographical introductions for the reissues of two Appalachian classics: Horace Kephart’s Our Southern Highlanders and James Mooney’s History, Myths, and Sacred Formulas of the Cherokees. In June 2005, a selection of his Back Then columns was published by The History Press in Charleston as Mountain Passages: Natural and Cultural History of Western North Carolina and the Great Smoky Mountains. Readers can contact him at P.O. Box 1262, Bryson City, N.C., 28713, or at This email address is being protected from spambots. You need JavaScript enabled to view it. .

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