Poison Ivy rambles freely over the eastern half of our continent, particularly in woodland areas. It grows as far north as Nova Scotia in Canada and as far south as Florida (Zones 3 to 9). It is found as far west as Texas, Nebraska and Iowa.
This wide range is probably due to its remarkable adaptability. It prefers dry soil, but tolerates soggy. It accepts either shady or sunny locations. It is susceptible to virtually no insect pests and very few, mild diseases. It resists soil compaction, pollution, flooding, infertile soil and drought. Furthermore, it transplants easily. No wonder it is everywhere.
Recognizing Poison Ivy
Foliage: Poison ivy foliage is three shiny leaflets from 2 to 4 inches long at the end of 10 inch stems which are attached to the main vine. Their edges may be toothed, smooth or even lobed. They unfold red or purplish in spring, then usually turn a shiny dark yellow-green for the summer. In the fall they show a duller red-orange. Some types of poison ivy have duller summer foliage. All types have leaf undersides that are paler than their tops. By early October the leaves of this deciduous plant fall, exposing its woody stems.
Flowers: Poison ivy flowers grow in bunches attached to stalks that are 1 to 4 inches long. They appear in late spring after the leaves have opened. Male and female flowers are on separate plants. A greenish white, they are inconspicuous, but they do have a fragrance.
Berries: Over the summer flowers give way to round, waxy, whitish berries. About 1/5 inch in diameter, each berry has longitudinal creases on its skin similar to those on a pumpkin. These fruits appear as loose drooping clusters in late September, and last for several months. While poisonous to people, they are coveted by song and game birds and small animals. In fact, poison ivy often reproduces itself through seeds that are spread by birds that eat the berries. It also spreads by means of its underground rhizomes, or spreading roots, or by its growing runners, vine stems, which increase the plant's spread across the ground, up trees, and along walls.
Similar Plants That Cause A Rash
There are several woody plants that also have the irritant urushiol and might be confused with poison ivy.
Poison oak looks and acts very much the same way as poison ivy. It has three leaflets which can vary in shape. It has white fruits and the foliage turns red in the fall, and it could be a bush, vine or a tree. One version (Rhus quercifolia) is native to the eastern and southeastern states and the other version (Rhus diversiloba ) is exclusive to California and the northwest.
Poison sumac (Rhus vernix ) has the same toxin urushiol, but the leaves are distinctly different having 7 to 13 leaflets and veins from which the leaflets grow are always red. Poison sumac has small fruit that is white or grey while the non-poisonous sumacs have red berries. Unlike poison ivy and poison oak, poison sumac grows almost exclusively in very wet or flooded soils, usually in swamps or bogs in the eastern states and eastern provinces of Canada.
Virginia Creeper Can Confuse
In the eastern states poison ivy is often mistaken for another common native called Virginia creeper (Parthenocissus quinquefolia). Virginia creeper has a similar growth habit and beautiful autumn foliage, but typically has five leaflets rather than three. It does not contain urushiol.