Poison oak and poison sumac often play second fiddle to their well-known cousin, poison ivy. Despite this, these plants are no less pervasive and their symptoms are no less irritating. Both poison oak and poison sumac are indigenous to North America. Learning how to identify poison oak and poison sumac can prevent the intense, uncomfortable effects of accidentally coming into contact with these plants in the garden or while enjoying a nature hike.
Identification of Poison Oak
Poison oak, known scientifically as toxicodendron diversilobum and sometimes by the common name of Western poison oak, is a plant found in the western portion of the United States and Canada. Poison oak comes in many forms, including a trailing vine and a single stemmed stalk, but most commonly manifests as a woody shrub. Poison oak leaves are generally separated into three deeply-lobed leaflets that resemble the leaves of an oak tree. Poison oak leaves are glossy in appearance and are typically red or orange in their first stages of growth, bright green during maturity, yellow-green as they age and red or pink as they approach dormancy in the fall. Poison oak produces small white flowers that turn into white or tan berries in the colder, winter months.
Identification of Poison Sumac
Poison sumac, or toxicodendron vernix, is found almost exclusively in the eastern portion of the United States and Canada. It is a woody shrub or tree, growing as tall as 20 feet under optimal conditions. Poison sumac is often confused with non-poisonous sumac trees. Both types of sumac have compound, alternate leaf structures composed of seven to 13 oval-shaped leaflets. While the foliage of poison sumac changes color throughout the year from red to green to pink, the leaf stems of this plant are always red. Poison sumac produces grayish-white berries, ripening in the fall and usually present when the tree is dormant in the colder, winter months. Poison sumac is primarily found in wet, swampy areas.
Poison oak and poison sumac plants contain the potent oil known as urushiol. Urushiol is found in all parts of the poison oak and poison sumac plants. The oil sticks to anything it comes in contact with, including skin, hair, pets and inanimate objects like clothing or gardening tools. It only takes 50 micrograms of urushiol to produce a rash in most people, according to a 1995 article in the American Botanical Society's newsletter "Herbalgram."
Within 24 hours of exposure to poison oak or poison sumac, a rash appears. The rash usually resolves within one to two weeks. Severe allergic reactions cause pustules or blisters to form on the skin. Treatment includes steroidal anti-inflammatory drugs and an antibiotic to prevent blisters from becoming infected with bacteria. Minor cases may be treated with over-the-counter itch-relief medications.
Learn to identify poison oak and poison sumac, and avoid them at all costs. Individuals with a severe allergy to urushiol oil need to be especially vigilant about avoiding these plants. If a rash develops and worsens to the point where pustules appear, or anaphylactic shock occurs, seek treatment from a licensed medical professional. Wear gloves when removing these plants from your gardening space, and dispose of the gloves afterward. Thoroughly wash shoes and any clothing items that have come into contact with poison oak or poison sumac.