Poison oak
Poison Oak, a shrub or small tree native to North America. It is distinguished by its three-lobed, oaklike leaves. The underside of the leaf is lighter than the surface and is covered with hair. Some shrubs bear hanging clusters of greenish-white berries. All parts of the plant contain urushiol, an allergen also found in poison ivy, which can cause an inflammation of the skin. The eastern poison oak is found from New Jersey to Texas. The western poison oak is found from British Columbia to Mexico.
The eastern poison oak is Toxicodendron pubescens; western poison oak, T. diversilobum. Both belong to the cashew, or sumac, family, Anacardiaceae.
Poison oak is distinguished by its three-lobed, oak-like leaves.