Leaves of Three - Let them Be

Did The Poison Ivy Get To You?

Summer is about being outside. No matter if you are into gardening, hiking, camping or playing man-hunt in the woods, you should be aware of poison ivy.

Along with poison oak and sumac, this non-flowering plant can cause severe allergic reactions, resulting in an intensely itchy, red rash with bumps or blisters.

If you go down to the woods today, you better wear long pants — socks, too, actually — preferably pulled up over your pants.

Poison ivy is not a plant to take chances with. Contact with its vines, leaves and roots can cause a devastatingly itchy, red, oozing rash caused by an oily compound called urushiol.


Despite poison ivy’s scientific name, Toxicodendron radicans, urushiol is not technically a toxin or poison. It is an allergen, meaning some people react to it with the hallmark rash and some don’t. But you can’t assume that because you were immune to it in the past that you will always be immune. People can develop a full-on allergic reaction to urushiol at any time.

The fact that urushiol is an allergen and not a toxin explains why butterflies can land on poison ivy leaves and bask there with impunity. And why other animals can eat its leaves with no ill results. Humans mount an aggressive allergic response to the compound through specialized cells called T-cells, while the bodies of other animals do not. Some animals, in fact, like white-tailed deer, appear to seek out and even prefer poison ivy leaves as forage.

Poison ivy loves edges, meaning you will often see it growing at the sunny borders of paths and trails and the edges of woods. It’s common, for example, in such locations in High Park and the spit’s Tommy Thompson Park.

So how can we humans avoid coming into contact with this nasty piece of business?

First of all, it behooves us to remember the old rhyme “leaves of three, let them be.” But many plants bear their leaves in triplets — consider the delicate, jagged little leaves of wild strawberry, for example — so that’s not much use. A more specific description of poison ivy leaves is of greater help: they occur in triplets, with the terminal or centre leaf, on a short reddish-coloured stalk, tending to be a bit larger than the paired side leaves, which are attached directly to the stem.

 Leaves of three - let them be!

Leaves of three - let them be!

Colour and shape aren’t of much assistance. Poison ivy leaves can be jagged or smooth, shiny or dull, notched or unnotched, as tiny as your fingernail when they first emerge to as big as your whole hand. They vary dramatically in colour, too, throughout the seasons, from shiny red in the spring, bright green in the summer, to any shade of yellow, orange or red before dropping off the plant in the fall.

Even the habitat of the plant varies: it can form huge colonies at ground level, appear as an erect shrub or be a vine that climbs trees. It is frequently found intermingled with the vines of Virginia creeper.

Since it is so hard to identify poison ivy in all its various guises, it is far better to avoid it altogether than to suffer the rash that accidental contact brings.

Never touch a plant you can’t identify. And if you do go down to the woods today — or anywhere off the beaten path — remember to wear long pants. You can dispose of the pants, but it’s devilishly difficult to remove urushiol from your skin.

Should you make contact with poison ivy try the following to minimize symptoms:

  1. Avoid touching other parts of your body. This is especially important immediately after exposure, since the irritating oils can be transferred to other areas.
  2. Rinse affected areas with plenty of cold water immediately after exposure to flush out oils, or wash with rubbing alcohol.
  3. Use an over-the-counter product known as Tecnu lotion, which works well to remove oils up to 24 hours after contact.
  4. If the itching has begun to develop, run hot water- as hot as you can stand - on the affected areas. The itching will briefly become intense, but then will stop for several hours, as the nerves that convey the sensory information to the brain become overloaded and quit. Repeat the hot water treatment as necessary - but be cautious to avoid burning.
  5. Relieve itching with aloe vera gel and calamine lotion.
  6. Try witch hazel (Hamamelis virginiana) to treat poison ivy blisters. Available in liquid distillation, it can be found at any drug store and can be safely used by both adults and children.

Keep in mind that serious cases of poison ivy require medical supervision and prescription treatment - contact your physician if you run a fever of 101 degrees or higher, if blisters ooze pus, or if the rash is widespread or near sensitive areas such as eyes, mouth or genitals.

Resources Dr. Andrew Weil www.drweil.com

Posted on July 14, 2014 .