Global warming helps poison ivy get upper hand on columnist

Here's a scary thought, just in time for Halloween.

Imagine a mild-mannered Daily Herald columnist (namely, me) suddenly covered inexplicably with a strange, unsightly rash.

It was not pretty. It was downright frightening.

"Poison ivy," nodded several knowing friends.

No way.

In a peculiar combination of genes and a funky immune system, I have never, ever been bothered by poison ivy. Actually, it has been a favorite parlor trick of mine to reach right into a batch of poison ivy and yank handfuls of it, smearing the alleged toxic oils all over.

Nothing ever happened.

To the delight and amazement (or perhaps the bemused tolerance) of friends and foes alike, I always was able to emerge unscathed from the ravages of poison ivy. I had no other particular physiological talents -- couldn't wiggle my ears, wasn't double-jointed, can't carry a tune -- but boy, could I ever pummel that poison ivy. Until now.

Had the poison ivy gotten stronger, or I weaker? I sought answers from the Web.

Can you believe global warming is now thought to make poison ivy more potent? Check out these recent headlines: "Poison ivy itchier, more plentiful with warming, study says" (National Geographic News, May 2006); "Poison ivy loves CO2 --there's the rub" (thedailygreen.com).

Evidently some studies have shown that poison ivy's toxic substance, urushiol, becomes stronger and the plant itself more prevalent, with elevated greenhouse gases.

I called Doris Taylor, plant information specialist at Morton Arboretum in Lisle, to confirm this horror tale.

Taylor acknowledged the studies and had noticed similar effects herself. Recently, she had had a serious reaction to the plant.

This was unusual because, like me, Taylor had never had serious reactions to toxic weeds like poison ivy. Now, instead of throwing down the gauntlet to fight the good fight against weeds, it's every man and woman for the nearest pair of gloves.

Spooky. Kind of got me thinking about dangerous plants in general. The arboretum's plant clinic has an interesting display and a number of references on poisonous plants.

Since fall is a good time to plant many shrubs, perennials and trees, and since Halloween is just around the corner, I figured it might be good to consider plant toxicity among my selection criteria for plants.

Some plants are well-known for their toxic attributes. Digitalis (foxglove) and its fatal heart effects have been featured in a number of whodunits.

Bittersweet nightshade not only sounds sinister, but has toxic results for animals.

Who would be tempted to plant poison hemlock (Conium maculatum L.)? Its name alone is scary, never mind the dire consequences the learned Socrates received from the hemlock family.

Yet, some of the least suspicious plants can have toxic parts. Taylor points out that all parts of rhododendron contain toxins -- specifically grayanotoxin. The foliage is especially toxic; chomp some leaves and you are in for some severe digestive disorders if not worse.

Kentucky coffee tree, a native Illinois tree that provides excellent shade and has a mature, elegant structure, also sports poisonous leaves, seeds and pulp.

Good old Japanese yew, that staple foundation plant of the 1950s, can be extremely toxic to animals. Red maple trees and hydrangea also have their poisonous personalities.

These are just some of the woody plants that might be on your list for planting this fall.

In the spring, there are even more perennials that have nasty side effects. See the University of Illinois' Toxic Plant Database (library.uiuc.edu/vex/toxic/comlist.htm) for a list of plants with a powerful punch.

The arboretum's plant clinic also has a number of references on poisonous plants. That doesn't mean you must avoid them, just give careful consideration if you have pets or small children.

In all cases of emergency, call your poison control hotline. Illinois' hotline is (800) 222-1222, and many local agencies also have an emergency number.

Of course, many toxins in plants are harmful only if ingested in large quantities. But then, there are those that pack a powerful punch -- witness this mild-mannered reporter with Halloweenish skin tones. Guess I'll have to learn how to wiggle my ears now.