Poison Ivy is a terrible plant, no doubt about it. It makes our lives just intolerable. The itch, rash, blisters, it is our immune system reacting to the oil of the plant, urushiol (yoo-ROO-she-ol). There is nothing inherently toxic about poison ivy, or its very close relatives poison oak and poison sumac. Birds eat the berries of the poison ivy. Wildlife and livestock can easily eat the leaves of the plant. It is the human race that cannot tolerate its oil. Once in contact with the skin, urushiol will get into the sublayers of our skin and our misery begins.
Statistics show that 70 - 85% of the population will react to as little as two micrograms of urushiol. This measurement is about a millionth of a tablespoon. Not very much to cause such a pain.
If you think you are immune to poison ivy, remember that immunity to urushiol will lessen with age. As a child, I was never effected by poison ivy, yet as an adult I suffer terribly.
Every part of the poison ivy plant, the stem, berry, leaf, and root contains urushiol. This oil will travel in weather and although it cannot travel through air, it can travel as smoke. If inhaled it can be serious. So, never burn the plants to destroy them.
Identifying the plant by "leaves of three, let it be" is a good start, but poison ivy can have anywhere from three to eleven leaflets. The leaves may also be waxy and have a "scoopy" appearance. Some poison ivy leaves are even fuzzy on their undersides. The growth pattern is sort of in a zig-zag formation. This is true in new plants. In a mature plant, the stems have tiny hairs. The leaves can be dull or shiny. The plant produces tiny white berries.
Poison ivy likes dry soils, but will also grow in wet clays. Although it prefers sun, it will also tolerate shade. Poison ivy will bloom between April and September.
In the fall the leaves turn red and drop. The plant is just as potent in its dormant state.
The interesting limitation to the plant is elevation. Poison ivy does not grow more than 4,000 feet above sea level.
The plant loves roadsides, ditches, trails, and fences. Your household pet can easily pick up urushiol oil and spread it by carrying it on its furry coat.
Clothing often can retain the oil for months even after repeat washing.
If you are subject to poison ivy there is some relief. See Skin Rashes from Plants