Outdoor gardening brings potential exposure to poisonous plants, and one such plant is poison sumac, or Toxicodendron vernix. This sumac grows in swampy areas and wet woods throughout the eastern United States and extends south through Texas and north through Minnesota to Canada. Identification of this plant, along with proper precautions, can save you from the assault of its toxic substance, urushiol.
Poison sumac belongs to the Cashew (Anacardiaceae) family, which comprises approximately 800 species of trees and shrubs worldwide, according to The Tree of Life Web Project. The fruits of this family include well-known edibles such as mango, pistachio and peppercorn, but, of course, you won't find poison sumac berries in the produce aisle. You may see these berries in the wild, however, and their color will help you distinguish them from the harmless sumacs of genus Rhus.
Toxicodendron vernix grows as a shrub or small tree that can reach up to 20 feet in height, according to Purdue University Extension. Its compound leaves, composed of seven to 13 individual leaflets , have a smooth and reddish stem, though the bark of the main trunk is grayish-brown. Small green flowers along the stems produce loose clusters of waxy, green berries, which then turn a whitish color when mature. The glossy, elliptical-shaped leaflets have smooth edges and turn from green to yellows and reds in autumn.
Several types of sumac grow within the same regions and share similar traits with poison sumac. It's helpful to learn about their distinguishing characteristics because, as "The Forager's Harvest" author Sam Thayer notes, you may stumble into "look-similars." These harmless and partly-edible sumacs, such as Staghorn sumac, produce upright cone-shaped clusters of crimson-colored berries. The edges of their leaflets are serrated, unlike the smooth edges of the poisonous variety.
Poison sumac contains urushiol, which is the same toxic substance secreted by poison ivy and poison oak. This oily substance seeps from the plant when damage occurs to any of its parts, such as a torn leaf, but the oil is sticky and can spread from one area to the next. Urushiol causes contact dermatitis and triggers itching, swelling, redness or fluid-filled blisters on the skin. Rashes from poison sumac may be more severe than those from poison ivy and oak.
Avoid contact with all parts of poison sumac. Do not burn this plant because severe respiratory problems can occur from inhalation of the smoke and its particles. Wear long sleeves and pants when around this plant, and wash the clothing in hot water and detergent immediately after use. The National Institute for Occupational Safety and Health recommends cleaning gardening tools with rubbing alcohol if they come into contact with poison sumac because urushiol oil remains active for up to five years.