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Western Poison Ivy Toxicodendron rydbergii (Toxicodendron radicans var. rydbergii)


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Western Poison Ivy, leaves
credit: U.S. Fish and Wildlife Service

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Family: Anacardiaceae, Cashew view all from this family

Description Toxicodendron rydbergii (syn. Rhus rydbergii; Western Poison-ivy) is native to most of the United States except the southeastern states. It can be found growing in forests, and other wooded areas, usually near streams and rivers.

It is a shrub that can grow to 1 m (3 ft) tall, rarely up to 3 m (10 ft). The leaves are trifoliate and alternate. The leaflets are variable in size and shape, and are usually 15 cm (6 in) long, turning yellow or orange in autumn. The fruits are small, round, and yellowish.

All parts of this plant contain Urushiol, which can cause severe dermatitis in some individuals.

Warning Do not touch; causes severe skin inflammation in people susceptible to its volatile oils. Berries poisonous if eaten.

Habitat Mountains, Cities, suburbs & towns, Scrub, shrub & brushlands, Grasslands & prairies, Canyons & valleys, Watersides (fresh), Fields.

Range Great Lakes, Northwest, Texas, Florida, Rocky Mountains, Southwest, New England, Southeast, Plains, Mid-Atlantic.