Common Name: Poison ivy, Rhus radicans (old synonym), markweed,
poison creeper, three-leaved ivy, picry, mercury
Family: Anacardiaceae
Lyman Orchards, Middlefield, CT
Plant is Native to: Midwestern, northern and eastern United States and parts of Canada.
Plant Height at maturity: Grows to 30 feet or more as a vine, and shrub form can grow about 1.5 feet tall.
Plant Habit and Form: Deciduous woody vine or subshrub; often has aerial roots, and rhizomes..
Foliage: Three leaflets, about 10 cm long. Margins are toothed, lobed to entire and vary in shape, but are mostly ovate. Alternate and petiolate. Petioles are densely pubescent. Leaflet stalks are short except on the middle leaflet.
Hill-Stead Museum, Farmington, CT
Bark: Woody. Reddish in the herbaceous portions of stem. When growing as a vine, attaches to trees or rocks by aerial roots. On older plants, these aerial roots give stems a hairy, fibrous appearance.
Town Farm Rd, West Simsbury, CT
Flower: Small, yellowish-green flowers on axillary panicles from May to July. Five petals, with five stamens.
Guilford, CT
Fruit/Seed: Greenish to grayish smooth white berries in late summer. Can persist on plant through winter.
Growing Requirements: Thrives under a variety of conditions and in almost any type of habitat; prairies, woodlands, glades, waste ground, fence rows, bluffs, thickets, roadsides, railroads, sand dunes, cultivated beds. Seeds are often dropped by birds.
Problems and Drawbacks: Poison ivy is the major cause of allergenic dermatitis in the eastern United States. All parts of the plant contain resinous compounds, known as urushiols, that cause inflammation of the skin, blistering and itching. These compounds can remain active on objects for over a year. Can be transmitted by direct contact with the plant or by contact with objects or animals exposed to the plant, and can occur at any time of the year.
Special Uses: Do not cultivate.
ID Tips/Remarks: "Leaves three, let it be. Berries white, take flight."
Hairy stems grow up tree trunks. Leaves are reddish in spring, medium green through summer, and red in fall. Yellow-green flowers and white berries in fall.
Bibliography:
Uva, Richard H, Joseph C. Neal, Joseph M. DiTomaso, Weeds of the Northeast, Comstock Publishing Associates, a division of Cornell University Press, Ithaca and London, 1997.
http://plants.usda.gov/java/profile?symbol=TORA2
http://www.missouriplants.com/Others/Toxicodendron_radicans_page.html
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