POISON IVY (TOXICODENDRON RADICANS)
Among wild plants, poison ivy (Toxicodendron radicans, T. rydbergii) is the cliché cause of skin irritation. It is a member of the otherwise tropical cashew family, which includes both cashew and pistachio nuts. Of the four related species found in Nova Scotian woods, lakeshores, and streamsides, three are irritants. The fourth, staghorn sumach, is a common, colourful autumn shrub that won’t make you itch at all.
In Nova Scotia, poison ivy is most common in the gypsum areas of Hants County and the sand dunes around Pictou and Antigonish Counties, but it can be found along stream banks, lake margins, and wet meadows elsewhere, as well. Indeed, the only place in Canada that seems free of this little treasure is Newfoundland.
Poison ivy has droopy, three-parted leaves that resemble Virginia creeper, except that vine has five leaflets. Poison ivy is also similar to groundnuts and other legumes found in similar habitats. These are herbs, while poison ivy is a woody vine or shrub. It is worth familiarizing yourself thoroughly with the appearance of this plant before you take a hike (see below).
All parts of poison ivy, even the pollen, are potentially irritating.
Volatile oils (principally urushiol), which can cause severe skin reactions, especially in spring and summer, when the plants are actively growing. Not everyone is equally sensitive to this toxin. Children develop allergic reactions typically after several exposures, but may “grow out of them” as they get older. The severity of symptoms is also greatest in cool, dry weather; heat and humidity render the toxin inert.
TYPICAL POISONING SCENARIO
Casual, accidental contact during hiking, camping, or other outdoor activities. Some, but by no means all, poison ivy habitats are posted with warning signs, like the one illustrating this page; it still pays to be familiar with the plant’s appearance.
Even inhaling the smoke from burning plants can cause permanent lung damage.
Contact with poison ivy causes, itching, burning, and redness of the skin, with blisters appearing up to five days after contact. Touching contaminated areas before they are thoroughly cleaned just spreads the irritant and should be discouraged. More-serious reactions include headaches, fever, and large blisters.
To treat poison ivy victims, first remove all contaminated clothing or footwear, and clean it carefully without direct skin contact. Residual plant oils on clothing can easily recontaminate unless it is thoroughly washed.
Next, wash all affected skin with strong soap and water, followed by rubbing alcohol. Antihistamine first-aid creams are often helpful, and a tincture (extract in alcohol) of calendula is also said to relieve the itching.
The leaves of jewelweed (spotted touch-me-not), crushed and immediately rubbed on affected skin, may prevent a reaction. It is often possible to find jewelweed in the woods in the same habitat as poison ivy.
POISON IVY POISON INFORMATION
Phenols are acidic compounds that can stop all functions of living cells by altering or binding proteins. The most notorious phenol plant poison in Nova Scotia is the irritant found in poison ivy and its relatives, but phenols are also found in nettles.