Species of poison ivy (Toxicodendron diversilobum) native to western North America and classified in the sumac (or cashew) family. Like many other lobe-leafed plants commonly called oak, poison oak is not an oak tree (genus Quercus).
This entry comes from Encyclopædia Britannica Concise.
For the full entry on poison oak, visit Britannica.com.
Seen & Heard
What made you look up poison oak? Please tell us what you were reading, watching or discussing that led you here.