When in the woods, remember, "Leaflets three, let it be"

Thursday, June 5, 2014
Poison ivy has clusters consisting of three divided leaves. Of note is that the center leaflet is on a longer stalk.

As outdoorsmen and women take to the woods and fields this time of the year, some will find themselves with burning and itching and blisters rising on tortured skin to alert them that they have come in contact with poison ivy.

One famous old rule of thumb that many of us learned in the Boy Scouts was, "leaflets three, let it be". That is an excellent rule for those who are sensitive to the menacing tri-leaved plant that covers large areas in this part of the country.

Many people don't realize that about half of the population has little or no reaction when exposed to poison ivy plants. But the reverse of that equation is that about half of humans show at least some negative reactions. Very few who react would consider the blistering and itching to be a minor reaction.

Poison ivy can grow as a low-growing vine, a shrub, or a vine that climbs, as this one did about 25 feet up a massive, old oak.

As the old adage states, poison ivy has three divided leaves. Of note is that the center leaflet is on a longer stalk. The plant also produces white, waxy berries along the stem in summer. Poison ivy is interesting in that it can grow as a ground-hugging vine, a low shrub, or a vine that can grow as much as 60 feet high on trees or other objects.

The plant produces small, greenish-white, fragrant flowers May through June, in clusters 1-4 inches long on the new growth of stems. August through November, berries (creamy white, waxy, globe-shaped, and usually smooth) ripen in grapelike clusters. The berries are not edible by humans but are useful to songbirds during fall migration and in winter. Animals, such as deer, browse on the foliage, twigs, and berries.

The part of the plant that is responsible for so much suffering in humans is the sap, an oil named urushiol, which sticks to clothing and skin. Reactions to urushiol include itching and blistering of the exposed bodypart. Interestingly, an individual's reaction to exposure can change from year to year.

If you think you may have been exposed to poison ivy, wash as soon as possible (Studies show that up to 50% of urushiol can be absorbed within 10 minutes.) with soap and cool water. Hot water can cause skin pores to open, drawing the oil into the skin. Even just rinsing in a running stream can help minimize reaction. Be sure to keep in mind that clothing can transfer the poisonous sap to careless or unknowing laundry persons.

Poison ivy produces berries that start green and turn white when ripe August through November.

There are various commercial products intended to help those who travel in poison ivy territory. Products, such as MultiShield®, are to be applied before expected exposure. Others, like Tecnu Skin Cleanser®, are made to cleanse exposed skin.

As mentioned earlier, poison ivy has beneficial uses to wildlife, but, if it grows in areas frequented by humans, one can't be blamed for controlling its growth. It can be sprayed with herbicides labeled for that. Glyphosate (sold as Roundup®, Kleenup®, and others) is a well-known indiscriminate killer that can be used on poison ivy but should be applied with care to keep from killing desirable plants as well as undesirable ones. Poison ivy is persistent so don't give up if it comes back.

Cutting and burning are effective but strongly discouraged as cutting can easily expose the worker to concentrated urushiol, and the oil can volatize when burned so that it can wreak havoc on skin exposed to the smoke, and even cause very serious respiratory problems if the smoke is inhaled.

For those who have the option, goats are a more eco-friendly option. These four legged friends can be penned up so that they concentrate their browsing on poison ivy patches. Haverford College in Haverford, Pennsylvania, has been reported to use a herd of 29 goats to control poison ivy and other broadleaf weeds on a 1 ˝ acre patch. "They'll work their way in and clean it up," said Bill Astifan, assistant director of the campus arboretum, the oldest in the nation."

At the time of the report, Astifan said, "The goats have already cleared out a section next to the road that was too thick to see through. It's now littered with gnawed-on branches."

Although one might be overjoyed with their caprine weed-eaters, caution is advised as even animals that don't react to poison ivy can transfer urushiol on their skin and hair. Other pets can do the same.

Those of us who don't react to poison ivy can go about our outdoor activities with little concern for it, but those sensitive to the plant can still have a good time with a little caution and preparation, and by keeping in mind the old warning, "leaflets three, let it be".

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