Poison sumac (Toxicodendron vernix) is a shrub or small tree that can grow as tall as 30 feet. It sports medium green leaves in the summer, which turn to a red-orange in the fall. And one of its defining characteristics is the red color of its stems. Best planted in the spring after the last frost, sumac grows at a moderate rate. Plus, the plant is native to North America, so it won’t upset the natural balance of flora. However, the toxicity of poison sumac makes it unadvisable for use in landscape applications. The goal is typically to eradicate it, not foster it. All parts of poison sumac contain an oily resin called urushiol, which can cause an itchy, burning rash in people via skin contact. (Animals are rarely affected.) Even inhalation of burning poison sumac can cause a reaction.
Toxicity of Poison Sumac
Poison sumac contains the same toxin, urushiol, that’s found in poison ivy and poison oak. But it’s much more concentrated in poison sumac, making some reactions especially severe.
All parts of the plant contain this toxin, and it even remains active in dead poison sumac plants. The most common symptom from contact with the plant is a painful skin rash, often with sores and blisters. This rash can be long-lasting and spread over a large part of the body, depending on your level of exposure and individual reaction to it. Moreover, inhaling burning poison sumac can cause inflammation and fluid accumulation in the lungs, which can be fatal. Likewise, ingesting the plant can cause inflammation in your gastrointestinal tract.
While poison sumac affects humans, animals don’t seem to be bothered by it. Birds and other wildlife even eat the berries from poison sumac plants. However, pets still can carry the toxic resin on their coats if they come in contact with the plant, which could then cause a reaction on your skin if you touch them.
If you need to work with poison sumac in your garden, always wear protective clothing: long sleeves and pants, rubber gloves, and boots. Thoroughly hose down your boots and gloves after you’re done in the garden, and immediately wash your clothes. It's ideal to take a shower as well just in case there's some resin on your body.
Symptoms of Poisoning
There are several symptoms of poison sumac toxicity, including:
- Itchy rash
- Burning sensation
- Blisters and sores
- Coughing and wheezing
- Difficulty breathing
The symptoms generally appear between eight and 48 hours after contact with the plant, and they can linger for weeks. If you suspect exposure, contact a medical professional. A rash that’s spreading over more than 30% of your body, a high fever, extreme swelling, and trouble breathing all are signs you should seek emergency care. Also, be aware that a skin infection might occur—often with pus and oozing sores—from scratching the rash.
Some common treatments include immediately cleaning the area with rubbing alcohol and then soap and water to remove as much of the resin as possible. Your doctor might then recommend anti-itch creams and other remedies to help reduce the symptoms.
Poison sumac will spread in your garden but usually not aggressively so. Thus, it’s typically not an issue for your other garden plants in terms of crowding them out and taking nutrients. The plant also will attract birds and other wildlife to your garden with its edible berries. Sometimes the berries stay on the plant through winter when other food sources are scare, which benefits the local wildlife. The plant also has ornamental value with its yellow-green blooms and bright red-orange autumn foliage. However, this still is not a garden plant you'd want due to its toxicity.
|Botanical Name||Toxicodendron vernix|
|Common Names||Poison sumac, thunderwood|
|Plant Type||Woody deciduous shrub or small tree|
|Mature Size||Up to 30 feet tall|
|Bloom Time||Spring and summer|
Poison sumac can be quite a large shrub with a thick stem that makes the plant look more like a small tree. It has feather-like leaves consisting of seven to 13 leaflets, each of which tapers to a sharp point. The leaves have a wavy edge, and the undersides are either hairless (glabrous) or have down-like hair (pubescent). The foliage has an orange hue in the early spring, turns medium green in the summer, and changes to red-orange in the fall.
Poison sumac’s red stems are one of its key identifiers. The plant produces small clusters of yellow-green flowers in the late spring and early summer, which turn to yellowish-white berries that remain through fall and even winter. New bark on poison sumac is a light gray color that darkens as the plant ages.
Where It’s Found
Poison sumac is native to North America and is mostly found in the eastern U.S. and southeast Canada. Its USDA hardiness zones are 3 to 8. The plant favors swampy areas with full sun to part shade. It thrives in fertile, acidic, moist soil and can even tolerate its roots in standing water.
How to Remove Poison Sumac
Poison sumac is somewhat difficult to remove, primarily because of its toxic nature. While wearing your protective clothing and eyewear, start by trimming the plant down to the ground with pruning shears. Make sure you immediately bag all the clippings and never burn them. Then, spray the area with a hose to loosen the soil. Dig around the plant’s root ball, pry it up, and put it in a yard waste bag as well. After removal, be cautious when removing protective clothing and immediately wash.
Search the soil for any remaining roots, as these have the potential to sprout new plants. You can cover the site with cardboard or a tarp for at least a full growing season to smother any new plants that try to grow.
As a last resort, you can use herbicide to get rid of poison sumac. However, these products often contain dangerous chemicals that can harm people, animals, and nearby plants.
Varieties of Sumac
There are multiple species of sumac that aren’t poisonous and make for great landscape plants. They include:
- Staghorn sumac (Rhus typhina): A shrub or small tree that grows from 15 to 25 feet tall and features reddish hairs covering its stems
- Fragrant sumac (Rhus aromatica): A dense, low-growing shrub at only around 2 to 6 feet tall that gives off a sweet citrus scent when its leaves and stems are crushed
- Evergreen sumac (Rhus virens): A medium-sized shrub at up to 12 feet tall with glossy evergreen foliage
Kim, Y., Flamm, A., ElSohly, MA., Kaplan, DH., Hage, RJ Jr, Hamann, CP., Marks, JG Jr, Poison Ivy, Oak, and Sumac Dermatitis: What Is Known and What Is New? Dermatitis, 30,3,183-190, 2019, doi:10.1097/DER.0000000000000472
Poison Sumac Toxicodendron vernix. North Carolina State University State Cooperative Extension.
Poison Ivy, Poison Oak and Poison Sumac. Cleveland Clinic.