Toxicodendron radicans is a native vine and shrub in the cashew family (Anacardiaceae), distributed across most of eastern North America. All plant parts contain urushiol, an oily resin that triggers allergic contact dermatitis in roughly 85% of people on first or repeated contact. The field mark is a trifoliate leaf with the center leaflet on a distinctly longer stalk; fall foliage turns vivid red to orange. It is not a true ivy.
Poison ivy colonizes disturbed edges, roadsides, woodland margins, stream banks, and fence lines. It spreads by bird-dispersed seed, rhizomes, and root sprouts, persisting tenaciously once established. Cutting without root removal stimulates resprouting. Burning cut material is dangerous — urushiol in smoke can cause severe airway inflammation. Repeated cutting every four to six weeks through the season, or a targeted foliar herbicide, depletes root reserves over two to three seasons. Wear full-coverage clothing and nitrile gloves for all contact.
Despite its hazard to people, it is a significant native resource. More than 60 bird species eat the white berries, including yellow-rumped warblers that depend on them during fall migration. Deer and other mammals browse the foliage without ill effect. Native American groups used dilute topical preparations for warts, ringworm, and certain skin lesions.