Poison sumac (Toxicodendron vernix) is a highly toxic plant native to the eastern United States and Canada, typically growing as a woody shrub or small tree. It is infamous for causing severe allergic reactions upon contact. Poison sumac does have flowers, but they are unassuming and not the plant’s most recognizable feature. This plant is a close relative of poison ivy and poison oak, all containing the same potent irritant.
The Reproductive Cycle: Flowers and Fruit
Poison sumac flowers are small and inconspicuous, appearing in the late spring or early summer. They are generally greenish-yellow or greenish-white with five petals. They grow in loose, drooping clusters called panicles from the leaf axils. Individual flowers measure only about an eighth of an inch across and bloom for roughly two weeks.
Once pollinated, the flowers develop into small, round fruits known as drupes. These berries are initially green but mature to a distinct whitish-gray or creamy-white color. The fruits are about a quarter of an inch in diameter and hang in drooping clusters. These berries often persist on the plant into the winter months, offering a helpful year-round identification clue.
Essential Year-Round Identification
Identifying poison sumac requires looking at its structure, not just seasonal features like flowers or fall color. The plant is usually found as a shrub or small tree, reaching heights of up to 25 feet. It grows almost exclusively in very wet, swampy areas, bogs, and marshes. This preference for saturated soils is a primary indicator, as non-poisonous sumacs are typically found in drier, upland habitats.
Poison sumac leaves are compound, meaning multiple leaflets grow on a single leaf stem in a feather-like arrangement. Each leaf has an odd number of leaflets, typically ranging from seven to 13, with a single leaflet at the tip. A key distinguishing feature is that the edges of these leaflets are smooth, or “entire,” lacking the serrated or toothed margins found on harmless sumac varieties.
The central stem, or rachis, to which the leaflets are attached, is often reddish, particularly on younger growth. The leaves turn a brilliant reddish-orange in the fall, making the plant highly noticeable. The combination of smooth-edged leaves, a reddish stem, and a wetland habitat is a definitive set of traits for recognizing Toxicodendron vernix.
Non-poisonous sumac species, such as Staghorn or Smooth sumac, have different characteristics. They possess a greater number of leaflets, usually 11 to 31, and their leaflet edges are distinctly serrated or toothed. Non-toxic sumacs produce berries that are red and grow in dense, upright, cone-shaped clusters, which differs clearly from poison sumac’s drooping, whitish-gray fruit.
Understanding the Threat: Urushiol Exposure
The danger associated with poison sumac stems from urushiol, a colorless or pale-yellow oil present in all parts of the plant, including the leaves, stems, roots, and fruit. Urushiol is a potent allergen that can remain active on surfaces, like clothing or tools, for up to five years. Exposure occurs through direct contact or indirectly, such as by touching contaminated objects or pets.
Inhaling smoke from burning poison sumac is hazardous because urushiol particles are carried in the smoke. This can lead to a severe internal reaction, causing inflammation and fluid accumulation in the lungs, which may result in respiratory difficulty. For most people, contact with the oil triggers allergic contact dermatitis, manifesting as an intensely itchy, red rash with swelling and weeping blisters.
If exposure is suspected, immediate action is necessary to minimize the reaction. The affected skin area should be thoroughly rinsed as soon as possible with rubbing alcohol, a specialized poison plant wash, or a degreasing soap, such as dish soap, and plenty of cold water. Rinsing frequently and preventing the wash solution from drying on the skin helps avoid spreading the urushiol. Relief from the resulting rash can be found using wet compresses, calamine lotion, or over-the-counter hydrocortisone creams. Medical attention should be sought if the rash is severe, covers a large portion of the body, or affects the face or genitals.