Toxicodendron vernix, commonly known as poison sumac, is a woody shrub or small tree growing to 9 m (30 ft) tall. It was previously known as Rhus vernix. This plant is also known as thunderwood, particularly where it occurs in the southern United States. All parts of the plant contain a resin called urushiol that causes skin and mucous membrane irritation to humans. When the plant is burned, inhalation of the smoke may cause the rash to appear...