Poison Oak and Poison Ivy: Identification and Control

Poison oak is most common in California, western Oregon, and western Washington. In open or filtered sun, it forms a dense, leafy shrub; in shade, a tall-growing vine. Leaves divided into three leaflets with scalloped, toothed, or lobed edges. Poison ivy is similar; common east of the Rockies and in eastern Oregon and Washington. Usually in shady areas and woodland edges, it sprawls along ground until it finds something to climb, then becomes a vine.

A resin on leaves, stems, fruits, and roots of both causes severe contact dermatitis in most people. Both spread by birds eating fruits and dispersing seeds. Most effectively controlled with appropriately labeled herbicide such as triclopyr or glyphosate (avoid contact with desirable plants).