Poison Ivy and Poison Oak: Identification, Eradication, and Home Treatment

By Sandra Dark
Published on March 1, 1981
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Poison oak is a shrubby ground plant that favors shaded woodland areas.
Poison oak is a shrubby ground plant that favors shaded woodland areas.
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These ridges of blisters are characteristic of both poison ivy and poison oak rashes, and are a sure sign that you've wandered through a patch of the toxic plants. Contrary to popular belief, breaking the blisters will not spread the dermatitis. Both species produce a deceptively attractive lush green growth.
These ridges of blisters are characteristic of both poison ivy and poison oak rashes, and are a sure sign that you've wandered through a patch of the toxic plants. Contrary to popular belief, breaking the blisters will not spread the dermatitis. Both species produce a deceptively attractive lush green growth.
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Poison ivy vines tend to climb trees or other upright supports.
Poison ivy vines tend to climb trees or other upright supports.
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Learn to recognize the plants by their alternate leaves with three leaflets per frond and you won't mistake the inoffensive five-leaved Virginia creeper vine for its dangerous neighbors
Learn to recognize the plants by their alternate leaves with three leaflets per frond and you won't mistake the inoffensive five-leaved Virginia creeper vine for its dangerous neighbors

Show me a homestead that includes a little patch of woods or the tiniest pond, and I’ll show you land that likely harbors poison ivy and poison oak. Or maybe just one or the other. The two plants are of different species, but contact with either results in the same itchy symptoms — and if you’re allergic to one or both of them (and most folks are), these leafy pests can sometimes make the “simple life” very, very complicated.

Over the past five years, I’ve learned more than I ever wanted to know about the “terrible two,” and most of that education was gained the hard way. In fact, my first poison oak outbreak was so severe that even the doctor looked at my swollen, blistered legs and stepped back in alarm! More than a score of other attacks — and a good bit of valuable trial-and-error learning — followed that memorably miserable August. Today, I’ve learned to share my two acres peacefully (more or less) with the dreaded enemy.

Identify the Adversary

The best way to avoid “catching” poison ivy or oak rash is to steer clear of the toxic plants. Unfortunately, few people learn how to identify them until after they’ve had a dose.

Poison ivy (Rhus radicans) is much more widespread — occurring throughout most of the United States — than is its “western” cousin poison oak (Rhus diversiloba), but both species have alternate leaves with three leaflets per frond. Poison ivy tends to vine (climbing trees, walls, and other upright supports), while poison oak is usually a knee-high shrub growing in shady areas. Both plants are deceptively attractive, and invite the unknowing stroller to collect bunches of the decorative foliage.

It’s important to know, too, that the dangerous plants are just as toxic during the winter months as they are in summer. And if there’s any itch worse than that of poison ivy/oak dermatitis during the hot weather, it’s the same rash when it’s under a heavy wool sweater! Remember always to wear protective gloves if you’re working in infested areas during the dormant season. When cutting firewood or pruning trees, beware of leafless vines!

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