Don't Touch: Spotting A 'Familiar Stranger' Could Keep Poison Ivy From Ruining Your Summer | Nashville Public Radio

Don't Touch: Spotting A 'Familiar Stranger' Could Keep Poison Ivy From Ruining Your Summer

Jun 1, 2018

The best way to treat poison ivy is to avoid touching it in the first place. But that's tricky, given the many faces the rash-inducing plant can have.

It was a close encounter in 2012 that made John Jelesko so interested in poison ivy as a niche academic pursuit.

He was cutting up a downed tree with an electric chainsaw. And the associate professor at Virginia Tech knew the axiom: "leaves of three, let it be." What he didn't realize was that his power cable had been dragging through poison ivy. So at the end of the day, as he coiled the cord around his palm and elbow, he inadvertently launched a career-bending science experiment.

"Within 48 hours, I had your classic case of poison ivy on my arm. And as a scientist, I said, 'this is interesting, how bad can it be? I'll just leave this untreated,'" he recalls, sheepishly. "In about two weeks, I had learned just how uncomfortable poison ivy rash could be."

It was enough to spark years of research into a plant he calls a "familiar stranger," given that it appears in almost every state in the continental U.S. But there's still little known about its unique properties, like why its leaves sometimes appear with jagged or lobed edges, and sometimes smooth.

Poison ivy is tricky like that, sometimes appearing with smooth edges. All of these photos were taken within a few miles of each other in South Cumberland State Park.
Credit Blake Farmer / WPLN

Here's what might be called the classic saw-tooth version.

These have a jagged edge.
Credit Blake Farmer / WPLN

But there are other variations, like this slight notching in the leaf.

People could easily confuse these plants.
Credit Blake Farmer / WPLN

There are "subspecies" of the Toxicodendron radicans, which is the scientific name. But Jelesko says he's seen different style leaves on the same plant. And while there are other native plants with three leaves, they don't show the same amount of variability in shape, Jelesko says.

"It's remarkable," he says, with a laugh. "There's just an enormous amount of things with this plant that are currently unknown."

Oddest of all, poison ivy can sprout up almost like a shrub.

This was the most shrub-like poison ivy found for this photo scavenger hunt, but Jelesko says they can be four or five feet tall.
Credit Blake Farmer / WPLN

Another rare property that gives fits to hikers and gardeners is the plant's ability to both grow as a creeping vine on the ground and climb a tree, like in the video below.

If mature enough, the vines can put out branches that can look just like the host tree. So simply pushing aside a branch could make a passer-by pay the next day.

This is a tree on the Virginia Tech golf course that died but is now covered in poison ivy.
Credit submitted by John Jelesko

Jelesko has even identified a dead tree overtaken by poison ivy on the Virginia Tech golf course.

From afar, it looks like it could be one of the evergreens nearby. Up close, it becomes clear that this is a nightmare of nature.

More fast facts:

  • If the plant has thorns, there's nothing to fear (except a scratch).
  • Dogs are not allergic. Scientists haven't found many animal that break out like humans do.
  • Jelesko says deer will even eat poison ivy, so researchers have ruled out the rash-making chemical as a defense mechanism.
  • Simply brushing up against the leaves or stems shouldn't cause problems, says this Penn State dermatologist. The oil is only released when the leaves or stems are broken.
  • There's a way to know for sure called the "black dot test." Tear the leaf in half, put the sap on a piece of white paper. If poison ivy, the urushiol oil will turn black in 30 minutes.
  • Experience does make a difference. For those who've never had poison ivy, it could take a week to develop. Repeat customers can start breaking out in a day or two.

When the tricky plant wins...

  • Soap and water within a few hours tends to prevent an outbreak in most people.
  • When a streaky, red rash appears, dermatologists recommend soothing it with anti-itch or corticosteroid cream.
  • And if it gets really bad, go to the doctor, especially if the rash involves sensitive areas like the mouth or genitals. Some people will even inhale it through smoke and require a round of steroids and possibly hospitalization.
  • But steroids and anti-itch medicine doesn't solve the whole problem. A researcher at Duke University found that part of the body's response involves a protein involved in immune response.

Of course, prevention is the best route. For John Jelesko, he now donns a Tyvek suit and two pairs of gloves when he's wallowing in poison ivy.

Spot the poison ivy mixed in with mostly Virginia Creeper.