Poison Ivy
and its Relatives
(Toxicodendron species)

Poison Ivy

Illustrations and photos by "Wildman," clipart from Clipart.com

Poison Ivy illustration
Poison Ivy Leaf and Flowers

These relatives of the cashew, mango, and the sumacs cause people more problems than any other plants, yet they're simple to avoid. After pointing out their different forms and asking people to locate them, even the kids are poison ivy experts by the end of one tour. The straightforward generic name comes from the Greek, where toxico means poisonous, and dendron means plant or tree.

Poison ivy (Toxicodendron radicans) has long-stalked, alternate, three-parted palmate-compound leaves. One leaflet points to the left, one to the right, and one has a stem and points straight ahead. The leaflets have some indentations on the edges that you could almost call teeth. The leaflets range from 4 to 14 inches long, with pointed tips, and more rounded bases. Their leafstalks are reddish near the leafís base.

These variable leaves are dark glossy-green most of the season, although they have red overtones when they first appear in the spring, and they turn scarlet in the fall. The plant is so beautiful in autumn, someone brought it to his garden in England, and now the British Isles are blessed with this plant.

Young Poison Ivy
Young Poison Ivy Leaves

Poison oak (Toxicodendron quercifolium on the East Coast, or Toxicodendron diversilobum on the West Coast), is nearly identical, except that its leaflets are partially subdivided into lobes. Botanists still argue over whether all these variants are really different species.

Poison ivy's general forms are also highly variable. It may grow as an herbaceous plant, upright shrub, or woody vine. The vine has aerial roots that anchor it to the tree or fence, but donít absorb nutrients. Dark, dense, hairy-looking aerial roots are a certain identifying characteristic in the winter.

Poison Ivy Vine
"Hairy Rope, Don't Be a Dope!"

Poison Ivy Vine with Hairy-looking Aerial Roots

Inconspicuous green and yellow flowers grow on branched, lateral stems bloom in late spring.
Poison Ivy Flowers
Poison Ivy Flowers
They're followed by small, round, berries in the summer and fall, green at first, then cream-white.
Poison Ivy Berries
Poison Ivy Berry Cluster
The berries are edible, but only if youíre a bird (the downy woodpecker eats the berries and spreads them through its droppings).
Poison Ivy Berries, Close-up
Poison Ivy Berries...

Closer than you ever want to be to them!

They're as poisonous to us as the rest of the plant: Leaves of three, let it be! Berries white, take flight!
Poison Ivy With Berries
Poison Ivy With Berries

Of course, other plants, like blackberries, raspberries, wild beans, and hog peanuts also bear three-parted palmate-compound leaves.

One of the good things about poison ivy and its relatives is that, unlike many other plants, it's always easy to find. It grows throughout North America, favoring disturbed habitats such as edges of trails, on fences, in fields, in marshes, in thickets, and woods. Because it needs plenty of sunlight, it doesnít grow in virgin forests or very old, undisturbed woods. Itís especially common at the seashore, where its roots help prevent beach erosion, and provide cover for small animals.

The plant is poisonous all year. I heard of a man who randomly picked up a poison ivy twig to chew on in the middle of the winter. His throat got so swollen, the hospital had to insert a breathing tube to save his life.

Poison Ivy Vine Close-up
Poison Ivy Wine Close-up
Poison Ivy RashThe poison is the yellow oil urushiol, a lacquer-like phenolic compound. It doesnít effect animals, but four out of five people are allergic to it. Exposure leads to severe skin blistering, contact dermatitis, usually within 1-12 hours. Washing with soap containing oils spreads the urushiol,

although washing with an oil-less soap or detergent (see your pharmacist) helps prevent the rash.

Avoid poison ivy even if you know you're not allergic to it, since repeated exposure may initiate allergy. Every time I pointed out poison ivy, one older German woman who regularly attended my tours would disobey me and shock everyone by holding a piece of poison ivy in her bare hands, innocently asking, in her thick accent: Mr. Brill, is dis dehr plant you mean?? She was immune, until one day, she showed up with bandages on her arms. She had flirted with danger once too often.

"What happened to you?" I asked."Yah, meester Brill," she repled. "You ver right. I no do dat no more!"The best way to prevent the rash is to rub juice from the broken stem of jewelweed on the affected area. Plantain species also help.A colleague is so sensitive that oil carried by the wind sets off a reaction. She tried a radical solution: eating poison ivy, starting with one very tiny leaflet in early spring, when the urushiol content is minimal. The next day she ate two, then three. I donít advise this risky approach: It may backfire, and I wouldnít try it myself. However, she was desperate, and it worked. She desensitized herself, and continues to consume tiny quantities for maintenance.Iíve heard that Pacific Northwest lumberjacks routinely protect themselves from poison ivy this way, but you can also get a bad rash where the poison ivy leaves enter the body, as well as where they exit (the treatment backfires)!

The Grim ReaperThe worst thing to do with poison ivy is burning it. (If it becomes necessary to eradicate this plant, uproot it in late fall, wearing protective clothing, when it has a minimum of poison).

The Boy Scouts Handbook forbids the use of any vine in campfires, to avoid such accidents: smoke carries the oil, producing a rash over 100 percent of the body.

Bill ClintonIf you inhale the smoke, you can get the rash in your throat, bronchial tubes, and lungs. This can be fatal, especially if youíre camping out, where thereís no hospital.

In fact, there's only one person in the world who doesn't have to worry about this effect, and it's someone with whom you're quite familiar: It's Bill Clinton ó he doesn't inhale!

"I tried it once, but I didn't inhale!"

Poison ivy inspired early twentieth century scientists to create weapons with substances as irritating to the human body as this plant. Thatís how the mustard gas of World War I, and subsequent biological warfare, originated.

Nevertheless, poison ivy has medicinal uses. An ointment of equal parts poison ivy vine, prickly ash bark, and alfalfa seeds is supposed to be good, applied externally, for arthritis. I donít know if it works, and I suggest you don't try to find out yourself. There are safer herbal and nutritional treatments. Poison ivy is also used in homeopathic medicine. Here, herbs are repeatedly diluted so many times, there are literally no molecules left in the medicine. This makes homeopathy difficult to understand from a scientific basis, but it's supposed stimulate the body's defenses against the symptoms the offending substance causes. The patientís constitution is more important than the symptoms in choosing the best homeopathic treatment, but for people with skin problems, poison ivy is often included in the regimen. Of course, there are conflicting claims about whether homeopathy works. Some people benefit from it, others donít, but it's safer than drugs.

Poison Ivy Shirt Design

UPDATE: Bigger, Better Poison Ivy Coming Soon to a Forest Near You!

Poison ivy is going to be getting much better. Researchers at Duke University investigating ecosystems of the future pumped high levels of carbon dioxide into a forest. Prevalence of poison ivy increased, along with the concentration of urushiol!

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