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Poison Sumac Toxicodendron vernix (Rhus vernix)


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Poison Sumac, leaves, berry and habit
credit: Tatters:) (Tatiana Gerus)/CCSA

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Family: Anacardiaceae, Cashew view all from this family

Description Poison sumac (Toxicodendron vernix or Rhus vernix) is a woody shrub or small tree growing to 7 m (20 ft) tall. It grows exclusively in very wet or flooded soils, usually in swamps and peat bogs, in the eastern United States and Canada. All parts of the plant contain a resin called urushiol that causes skin and mucous membrane irritation to humans. When burned, inhalation of the smoke may cause the rash to appear on the lining of the lungs, causing extreme pain and possibly fatal respiratory difficulty.

Poison sumac is a shrub or small tree, up to 20 feet in height, with 7-13 leaflets per pinnate leaf. These are oval to oblong; acuminate (tapering to a sharp point); cuneate (wedge-shaped) at the base; undulate (wavy-edged); underside is glabrous (hair-less) or slightly pubescent (down-like hair) beneath, and are usually 2-4 inch long. Its flowers are greenish, in loose axillary panicles (clusters) 3-8 inches long. The fruits are subglobose (not quite spherical), gray, flattened and about 0.2 inches across.

In terms of its potential to cause urushiol-induced contact dermatitis, poison sumac is far more virulent than its relatives poison ivy and poison oak. According to some botanists, poison sumac is the most toxic plant species in the United States (Frankel, 1991).

Warning One of the most dangerous North American plants. The clear, very toxic sap turns black on exposure and, for many people, causes a severe skin rash upon contact.

Habitat Swamps (fresh & salt), Watersides (fresh).

Range Great Lakes, Plains, Mid-Atlantic, Florida, Eastern Canada, Southeast, New England, Texas.