Poison ivy (Toxicodendron radicans)
Tracheophyta: Angiosperm: Dicot: Cashew (Anacardiaceae)
Native North American Plant
Habitat: full sun areas on tree trunks.
ID Features: hairy vine, leaves with 3 leaflets, joined by petioles, assymetrical toothing in leaf edges.
Natural History: Poison ivy grows as a vine or a small shrub when it has no tree to climb on. It has pinnately compound leaves with 3 irregularly toothed (sometimes untoothed) leaflets. The flowers are small and white or greenish-white while the fruit is white, sticky berries dispersed by birds. It grows at the forest edge, where it can find trees to parasitize and still receive enough sunlight to grow. It produces an oil called urushiol which is a major skin irritant to humans.
Missouri Wildflowers by Edgar Denison, 5th Edition, Missouri Department of Conservation, ©1998.