Poison sumac (Toxicodendron verni), also known as poison elder and poison dogwood, is a shrub or small tree that grows beside ponds and in marshes from Maine south to Florida and west to Texas where it is found in bogs and swamps along the Gulf Coast of East Texas. All parts of poison sumac, except the pollen, contains a toxic substance called urushiol that can cause itching and blistering of the skin, symptoms similar to those caused by poison ivy.
Poison sumac grows as a shrub that is 5 to 6 feet high or a tree that can grow up to 25 feet high. The bark of poison sumac is gray to blackish and may be smooth or slightly streaked; the clear sap quickly turns black when exposed to the air. Poison sumac yields yellow-green flowers that produce grayish-white berries in slender, drooping clusters where the leaf stems meet the branches.
The leaves are the most telltale physical detail of poison sumac. The leaves grow on red stems; they oval shaped, but are V-shaped at each tip. The leaves have smooth edges, and they turn red in the fall. For images of poison sumac showing details of the leaves and stems, see Resources.
The poison in sumac is contained in the sap. It can be passed by clothing, tools, firewood, animals or anything else that has touched the plant. The allergen turns skin red and itchy, causing it to swell and blister. Poison sumac is far more virulent than either poison oak and poison ivy.
Dwarf sumac (Rhus copallina), smooth sumac (Rhus glabra) and staghorn sumac (Rhus typhina) are harmless plants found in drier, upland habits not preferred by poisonous sumac. They produce red fruits; poison sumac yields grayish-white berries. Poison sumac produces no more than 13 leaflets with smooth edges on each stem; dwarf, smooth and staghorn sumac produce more than 13 leaves that have serrated edges.
The U.S. Army Public Health Command says dermatitis is apparently anaphylactic, meaning that it appears only after previous exposure. The symptoms usually surface within 12 to 24 hours, but they may appear as rapidly as three to four hours or not until several days have passed. Contact with the mouth, nose or eyes is considered dangerous. After contact, the skin should be washed with soap and water.