Be aware of poison ivy

The lovers of the outdoors are a hardy breed. They have to be because, in addition to the myriad of blood-sucking insects and their kin that attack without mercy, the outdoors person must be ever on the alert for a pernicious member of the cashew family, poison ivy (Rhus toxicodendron).

This rather attractive plant is quite common throughout the Rock River Valley. It is found in many locations, including fencerows, woodlands, thickets, and orchards. The leaves, stems, flowers and berries of the plant all contain the vesicating oil toxicodendrol, and individuals must take care to avoid contact with any part of the plant. Even a small amount of the irritating substance will induce intense itching and the formation of blisters over a wide portion of one’s anatomy.

Poison ivy prefers to grow as a vine that clings to trees by aerial rootlets (grapevines lack aerial rootlets), but it frequently assumes the form of a woody shrub if no tree is nearby. With a root system that is shallow, low, and widely spaced, large areas may become infested once a pioneer plant has become established. Birds are immune to the effects of toxicodendrol and readily feast on the white berries. The fleshy part of the berry is digested, leaving the seed to pass through a bird’s alimentary tract to be eliminated from the body elsewhere.

I am frequently asked how poison ivy can be readily identified, and I reply that if the plant is a woody vine or shrub, with alternating leaves, each leaf with three leaflets you should assume it is poison ivy. The small pearly-white berries are not present at all times of the year. Though it is true, a few other plants will fit this description; attempts to distinguish between them will only complicate matters. Better to be safe than sorry.

The toxic oil is not volatile, but droplets of the material can be carried considerable distances by smoke if the plant is burned, and respiratory poisoning can result if the airborne droplets are inhaled. The oil may adhere to clothing, tools, and the fur of pets if they have contacted the ivy. A sensitive person may react to the toxic oil simply by petting their dog after the pooch has returned from a romp in the woods.

The first noticeable symptoms of dermatitis produced by poison ivy are a reddening of the skin, followed by swelling. Tiny blisters soon appear, and the irritation and itching intensifies to the point of actual pain. Symptoms may appear a few hours after contact, or they may remain latent for a few days.

Some individuals are more susceptible to toxicodendrol than others, and a few lucky ones appear to be actually immune to the oil. This immunity, however, is quite variable, and frequently a person who for years thought he was resistant to poison ivy is surprised when he sustains an attack.

Years ago, my grandmother told me a tale of a man in the hills of her native eastern Tennessee who would frequently stuff a handful of poison ivy leaves down his gullet to prove his infallible resistance to the plant. She recalled he performed this trick once too often, and “They gave him a nice burying.”

Remedies to counteract the effects of poison ivy are many and are deeply rooted in folk medicine. Some of the “surefire” remedies recommend the application of kerosene, ammonia, baking soda, urine, aloe vera, gasoline, and an alcoholic solution of sugar of lead (lead acetate). The truth of the matter is none of these so-called cures for poison ivy dermatitis is very effective, if at all.

Washing the affected area with hot soap and water and the application of an ointment containing a local anesthetic or cortisone is probably the best course of action to take. The reaction may be quite severe in sensitive people; one should not hesitate to seek the services of a physician if the reaction is unusually harsh.

Dr. Robert Hedeen is a former resident of Maryland’s eastern shore and resided in the Chicago area from 1960-1971. He is a retired professor emeritus of biological sciences in the University of Maryland system. He has published more than 30 scientific papers, has written numerous magazine articles, and is the author of two books on the natural history of the Chesapeake Bay.

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