What Is Poison Ivy?
Poison ivy
Virtually everyone in the United States east of the Rocky Mountains has heard the phrase “Leaves of three, let it be.” This maxim, of course, is referring to the three leaves of the poison ivy plant. Poison ivy (Rhus toxicodendron, Toxicodendron radicans) is a plant commonly found in wooded areas in the eastern three-quarters of the United States and Canada. It prefers to grow at the borders of wooded areas, on trees and wooden posts, but can survive in reasonably shady areas and in underbrush. Except for the “three leaf” orientation, the poison ivy plant looks fairly unremarkable.
What does poison ivy look like?
The “leaves of three” adage is fairly accurate in that the poison ivy plant usually develops leaves in sets of three. However the answer to the question “what does poison ivy look like?” can be a bit challenging when compared to different green plants among a forest of foliage. Poison ivy has broad leaves (generally) that are wider at the base and taper in jagged borders to the tip. In some instances the leaf border is smooth. Perhaps the easiest way to establish what poison ivy looks like is to see pictures of it in various forms (shown above).
Poison ivy contact dermatitis
The term “poison ivy” has become synonymous with the rash that one gets from coming into contact with the poison ivy plant, as in “I have a case of poison ivy.” Poison ivy, in this regard, is a classic example of an allergic contact dermatitis. It is caused by urushiol oil that is contained within the leaves, branches, berries, and flowers of the poison ivy plant. When the outer covering of any of these plant parts becomes disrupted, the oil is released. If you are among the 70% of individuals in the United States that is allergic or susceptible to urushiol oil, you will get a poison ivy rash.
Urushiol oil
Urushiol (pronounced you-ROO-shee-all) oil is very sticky and, in people allergic to poison ivy, is very potent. Urushiol oil is actually a mixture of at least eight chemically related compounds. The compounds dissolve in alcohol but are barely soluble in water, making washing up after exposure quite difficult. To make things worse, the reaction to urushiol oil is delayed for a period of time after contact. That means that exposure to urushiol oil can occur without an immediate skin reaction—people can be exposed without realizing it.
How is poison ivy or urushiol oil contracted?
For as difficult as it is to recognize and remove urushiol oil from the skin, poison ivy contact dermatitis can be terribly easily to contract. The oils from poison ivy can be spread through direct contact with the plant or by touching someone or something that has urushiol oil on it. Even burning poison ivy leaves can carry urushiol oil and deposit it on the skin, which can also lead to a poison ivy rash.
