Peril in the plant kingdom

Poison ivy with shiny fresh growth                                        John/Flickr

Poison ivy with shiny fresh growth                                        John/Flickr

Poison ivy. It’s the bane of gardeners, hikers, campers and outdoor types everywhere, and one of Mother Nature’s most venomous creations.

Ask anyone who has suffered with the itching, oozing, blistering after-effects of a brush with this demon plant. While poison sumac is found chiefly in the swampy areas of the Southeast and poison oak is more common along the West Coast, poison ivy grows happily in New Jersey’s woods, parks and back yards.

Your first defense is knowing how to identify it, so you can avoid intimate contact altogether. That can be easier said than done, since this devious plant does not look uniform from place to place, and changes its appearance with the seasons. The maxim "leaves of three, let it be" is a good place to start, but poison ivy actually can have leaflets that vary from three to nine, so go cautiously into the unknown.

The leaves themselves are smooth, shiny and often tinged with red or purple when they first emerge in the spring, but they fade to a dull green by summer. Come fall, they turn a brilliant scarlet, often tempting unwary foliage collectors to add them to their woodland bouquets.

Technically, the plant is a vine. But it can spread across the ground like a hardy ground cover, imitate a free-standing shrub or clamber up a tree with aerial roots as thick around as your wrist. I only realized that those hairy-rooted vines disappearing up my locust trees were, in fact, poison ivy when I saw a similar specimen neatly labeled as such in a wildlife refuge on Maryland’s Eastern Shore.

Hairy poison ivy holdfasts                              Jay Cross/Flickr

Hairy poison ivy holdfasts                              Jay Cross/Flickr

It’s not just the leaves, but also the stems and roots that can give you a rash from hell. All parts of the plant, growing or dormant, contain urushiol (pronounced oo-roo-shee-ohl), a sticky oil that in sensitive people produces blistering and itching in 12 to 48 hours.

The stuff is potent and extraordinarily durable. An amount that fits comfortably on the head of a pin can infect 500 people, and its effects are so long-lasting that traces found in a 1,000-year-old Chinese jar caused the typical dermatitis. Except for a few primates, animals are unaffected, but you can pick up a rash from your dog’s fur if he has been rolling in poison ivy — or from a coat, gloves, garden tools or toys that have contacted the sap.

If you identify poison ivy in your yard, first learn what you should NOT do. Don’t go after it with the weed whacker, spraying yourself with macerated leaf bits. Don’t handle the plants without protective gloves and, above all, don’t burn the vines or any firewood that may have dead poison ivy still attached. You can become seriously ill (even seriously dead) by inhaling the fumes, which can blister your nasal passages and lungs.

Manual removal will reduce poison ivy stands but not eliminate them if you fail to pluck out every last root. It’s better in this instance to use a systemic herbicide like Roundup, containing glyphosate, which eventually will kill root, leaf and stem. (You can use a brush to carefully paint it on leaves. Follow directions to the letter!) Beware of poison ivy killers containing triclopyr, since this can get driven into the ground, causing die-back in deep-rooted trees and shrubs.

For those big, thick vines on your trees, suit up with double gloves (latex over cotton), long sleeves and eye-protection, and then using a hacksaw blade, cut through the aerial roots about 2 feet from the ground. Everything above the slice will die without further ado; wait until the bottom remnant sprouts leaves, then spray or paint as above. Needless to say, bag up the blade and gloves and throw them away.

Poison ivy berries                         Sam Fraser-Smith/Flickr

Poison ivy berries                         Sam Fraser-Smith/Flickr

You’ll want to remove as many of these big, mature vines as possible, since they are the ones producing berries, which birds eat without ill effect. The seeds are ejected (along with a little avian fertilizer) to sprout wherever birds perch to digest their dinners.

There are three nonprescription products that the poison-ivy prone should know about.

Ivy Block lotion, applied before potential exposure, serves as a barrier that can prevent rashes. Technu Oak-and-Ivy lotion and Zanfel are cleansers that remove the urushiol from your skin and from contaminated objects. These products can be found at some pharmacies including CVS, Rite Aid and Walgreens, or ordered online from amazon.com.

I must confess that there was one occasion when I took some small pleasure in the noxious effects of poison ivy. I was checking out fall migrants at Sandy Hook’s birding platform when a woman came down the trail with a gigantic bunch of wild blue asters in her arms — wildflowers that should have been left in place for everyone to enjoy.

The flowers she illicitly gathered were growing in a sea of poison ivy, but I didn’t say a word as she walked smugly past, admiring her ill-gotten bouquet. I’m pretty sure she didn’t hear me mutter (with unbecoming glee), "There is a God."