Toxicodendron is a genus of in the sumac family, Anacardiaceae. It contains woody , and , including poison ivy, poison oak, and the lacquer tree. All members of the genus produce the skin-irritating oil urushiol, which can cause a severe allergic reaction. The generic name is derived from the Greek words ( toxikos), meaning "poison," and ( dendron), meaning "tree". ξ1 The best known members of the genus in North America are poison ivy (T. radicans), practically ubiquitous throughout most of eastern..