Toxicodendron diversilobum (syn.
Rhus diversiloba), commonly named
Pacific poison oak or
western poison oak, is a woody vine or shrub in the
Anacardiaceae (sumac) family. It is widely distributed in western North America, inhabiting conifer and mixed broadleaf forests, woodlands, grasslands, and
chaparral biomes. Like other members of the
Toxicodendron genus,
T. diversilobum causes itching and allergic rashes in many humans after contact by touch or smoke inhalation.