Toxicodendron rydbergii, the western poison ivy[3] or northern poison oak, is a species of Toxicodendron in the cashew family native to North America.

Unlike Toxicodendron radicans (eastern poison ivy), which often appears as a trailing or climbing vine, T. rydbergii is a shrub that can grow to 1 m (3 ft) tall, rarely up to 3 m (10 ft).

The leaflets are variable in size and shape, and are usually 15 cm (6 in) long, turning yellow or orange in autumn.

It is native to most of Canada from the Maritimes to British Columbia, and most of the contiguous United States except the Southeast, Nevada, Oregon and California.

[1] It can be found growing in forests, and other wooded areas, usually near streams and rivers.