About Toxicodendron rydbergii (Small ex Rydb.) Greene
Description: Unlike eastern poison ivy (Toxicodendron radicans), which often grows as a trailing or climbing vine, Toxicodendron rydbergii is a shrub. It usually reaches 1 m (3 ft) tall, and rarely grows as tall as 3 m (10 ft). Its leaves are alternate and trifoliate. Leaflets vary in size and shape, and are typically 15 cm (6 in) long; they turn yellow or orange in autumn. On these compound trifoliate leaves, the two opposing leaflets are generally asymmetrical, while the terminal leaflet is always bilaterally symmetrical. The fruits are small, round, and yellowish. Like all other species in the Toxicodendron genus, every part of this plant contains urushiol. Distribution and habitat: This species is native to most of Canada, ranging from the Maritimes to British Columbia, and most of the contiguous United States. It is not present in the Southeast, Nevada, Oregon, and California, and is apparently extirpated from West Virginia. It grows in forests and other wooded areas, most often near streams and rivers. Toxicity: Because it produces urushiol, contact with this plant can trigger severe contact dermatitis in most people.
