Toxicodendron vernix (L.) Kuntze

Poison Sumac; Thunderwood; Swamp Sumac

Shrub

Perennial

Vascular

Poison Sumac is a native shrub or small tree in the Sumac family (Anacardiaceae). It occurs statewide in Alabama, though it is only infrequently collected. Poison Sumac grows in seeps, bogs, wet depressions, and non-alluvial swamps. It can occur as a single stem or a clump of stems, and grows between 3-25 feet in height. It infrequently branches, and the deciduous leaves are near the end of the stems. The bark is gray and has conspicuous lenticels. Young twigs are smooth and reddish in color. Leaves are alternate and pinnately compound. The petioles and rachis are red in color. There are 7-13 oblong or elliptic leaflets. Leaflets are glabrous with entire margins. Leaves turn red or orange before falling in the autumn. Poison Sumac is often dioecious, with separate plants producing either male or female flowers. Some plants produce perfect flowers (with both anthers and pistils). Flowers are produced in axillary, drooping panicles. Each flower has five greenish-yellow petals. The fruit is a white drupe. All parts of the plant produce the volatile compound uroshiol. This causes the allergic reaction of swelling, itching, and a rash. This is the same compound found in the related species of Poison Ivy (Toxicodendron radicans (Linnaeus) Kuntze) and Poison Oak (Toxicodendron pubescens P. Miller). Sensitive people do not have to come into direct contact with the plant. They can react to the compound on clothing, pets, or in the air. Poison Sumac differs from Sumacs in the genus Rhus by having leaflets with entire margins and having white drupes. Members of the genus Rhus have leaflets that are toothed and red fruit. Poison Sumac also tends to grow in wetter sites than the members of the genus Rhus.--A. Diamond

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Native OBL (NWPL)

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