Poison sumac

Appearance

Poison sumac is a shrub or small tree, growing up to nearly 30 ft in height. Each pinnate leaf has 7–13 leaflets, each of which is 2–4 inches long. These are oval-to-oblong; acuminate ; cuneate at the base; undulate ; with an underside that is glabrous or slightly pubescent beneath. The stems along the leaflets are red and the leaves can have a reddish tint to them, particularly at the top of the plant. New bark for a poison sumac tree is lightish gray, and as the bark ages, it becomes darker.

Its flowers are greenish, growing in loose axillary panicles 3–8 inches long. The fruits are subglobose, whitish-gray, flattened, and about 0.2 inches across; these are eaten by birds.

Poison sumac fruit are creamy white and part of a cluster. Typically, they are around 4 to 5 millimetres in size.

The fruit and leaves of the poison sumac plant contain urushiol, an oil that causes an allergic rash upon contact with skin. They are, however, not toxic to birds or other animals, and eaten by them when other food is scarce, especially in winter.

Distribution

Poison sumac grows exclusively in wet and clay soils, usually in swamps and peat bogs, in the eastern United States and extreme southeast Canada.

Defense

In terms of its potential to cause urushiol-induced contact dermatitis, poison sumac is more toxic than its relatives poison ivy and poison oak.

The differences in toxicity in poison ivy, poison oak, and poison sumac are due to differences in the side chains of the chemicals in these plants. In general, poison ivy has a C15 side chain, poison oak has a C17 side chain and poison sumac has a C13 side chain.

The dermatitis shows itself in painful and long continued swellings and eruptions. In the worst case, smoke inhaled by burning poison sumac leads to life-threatening pulmonary edema whereby fluid enters the alveoli.