Poisonous to Touch Weed Series: Poison Sumac (Toxicodendron vernix)

Poison Sumac (Toxicodendron vernix). Photo credit: James H. Miller & Ted Bodner, Southern Weed Science Society, Bugwood.org

Poison Sumac (Toxicodendron vernix) is a perennial shrub or small tree, native to eastern Canada as well as east-central and eastern United States. Like poison ivy and poison oak the leaves and berries of this plant contain urushiol (an oily mixture of organic chemical compounds); but the oil is said to be more concentrated in poison sumac. The Urushiol can cause a severe allergic reaction in sensitive individuals. An allergic reaction consists of intense itchiness followed by an itchy, burning, red, swollen rash, that develops painful blisters. Inhaling the smoke of burning sumac can be fatal and ingesting the plant can cause painful sores in the gastrointestinal track. The reaction naturally lasts for about 2-4 weeks. Luckily this plant only grows in swampy, boggy areas (where it can form large thickets) and is quite uncommon.

Identification of Poison Sumac

Overall Growth Habit: Like other sumacs, it leaves out much later in the spring than many other trees and shrubs. It grows as a small tree or tall shrub. As a tree it grows up to 6 m tall (20′) with a 10 cm (4″) trunk diameter and a small rounded canopy.

Leaves:  The compound leaves are comprised of 7 to 13 leaflets arranged opposite with 1 pointy tipped terminal leaf that measures up to 30 cm (12 inches) long. Individual leaflets appear bright orange in early spring, maturing to lustrous dark green on the upper surface and whitened or paler on the undersides. They measure about 2 to 3½ inches long, 1 to 1½ inches wide and have smooth edges (no teeth or lobes). The leaflets are stalkless, (or nearly so), except for the terminal leaflet which has a petiole that is often reddish and up to 1 inch long. The leaves alternate up the stem and turn brilliant orange or red in autumn.

Poison Sumac (Toxicodendron vernix) leaves. Photo credit: Troy Evans, Great Smoky Mountains National Park, Bugwood.org
Poison Sumac (Toxicodendron vernix) leaves. Photo credit: Keith Kanoti, Maine Forest Service, Bugwood.org

Stems and branches: Are reddish, slender and drooping, hairy when young but become hairless as they mature (N.C. Cooperative Extension n.d.). The bark is smooth and grayish brown. Another useful identification tool is looking for black markings on winter twigs, trunk and stems. Urushiol turns black when it comes in contact with the air.

Trunk: relatively smooth and light grey.

Flowers: The flowers are yellowish-white drupes. Individual flowers have petals.

Berries and Seed: Hard white berries that hang from thin stalks in drupes.

Poison Sumac Look A-likes

Staghorn Sumac (Rhus typhina): are not poisonous and the leaves are toothed not smooth like poison sumac. They have soft hairs on the twigs which makes them velvety to the touch, and they have red, upright fruit that are also velvety. They grow in dry soils rather than wet bogs.

Smooth Sumac (Rhus glabra): are not poisonous and the leaves are toothed not smooth like poison sumac. Their branches are upright and they have pointy red fruit clusters. These fruit clusters are smooth rather than velvety like staghorn sumac. They grow in dry soils rather than wet bogs.

Shining Sumac (Rhus copallina): are not poisonous and also have leaflets with smooth edges (entire), but they are distinguished by winged central leaf‐stems. They also grow in dry soils rather than wet bogs.

Tree of Heaven (Ailanthus altissima): are not poisonous, have notched leaves and have a heavy cascade of seeds, rather than berries.

Where Does Poison Sumac Grow?

Poison Sumac is native to the Eastern Unites States and up into the southern tips of Ontario and Quebec. It’s occurrence is quite rare in Canada.

Plants-NRCS Logos
Distribution maps from the U.S. Department of Agriculture displayed here in accordance with their Policies).

Habitat: is found primarily in bogs, marshes, swamps, flood plains and thickets along river banks. It prefers acidic soil and full to partial sunlight.

How Does Poison Sumac Spread?

Poison sumac reproduce by seed.

Symptoms Of A Poison Sumac Reaction

As mentioned in the introduction, skin reactions to the urushiol oil found in poison sumac are actually an allergic reaction known as contact dermatitis. Exposure to the oil, whether it be contact with the plant it’s self or contact with any surface that has any residue of urushiol on it, such as pets fur, lawn mowers, shoes, shoe laces, clothing, golf clubs, etc. can cause a skin reaction. It does not take much Urushiol oil to have a reaction. It is so potent that only one nanogram (billionth of a gram) is needed to cause a rash (Gov. of Canada 2016)

Classic symptoms include:

  • Intense itchiness
  • Rash that may appear within 24 hours to seven days.
  • Swelling
  • Redness
  • Painful blisters
  • Difficulty breathing, if you inhale the smoke from burning poison ivy.
  • Gastrointestinal inflammation if ingested.

The severity of your symptoms depend largely on how much urushiol you get on your skin and how sensitive the individual is to the oil. It is quite common for a person who was not sensitive to urushiol oil in the past to suddenly become sensitive to it.

Note: The puss from the oozing sores will not spread it to other parts of your body or to others.

What to do if You Come Into Contact With Poison Sumac

If you are in a swampy or boggy area and are fortunate enough to spot the plant and realize you have made contact the first thing you should do is get out of the sun and heat and wash it off with cool water and soap. The sooner you wash it off the less urushiol you will absorb into your system and cool water is recommended as hot water opens the pores and increases the spread. If you do not have soap you can use rubbing alcohol diluted with water (1/2 cup to 1/2 cup of water) or vinegar (2 tablespoons in 1 cup of water). Thoroughly clean any surface you may have contacted after touching the plant, using gloved hands. Wash the clothing you are wearing, shoes and shoe laces, gloves, door handles, etc.

If you are experiencing the symptoms but are unaware of where you came in contact with the plant or the urushiol oil then still follow the above steps but you will likely have to broaden your disinfecting area as you will have touched many more objects.

If your reaction is strong visit your doctor who will prescribe a topical corticosteroid cream to apply to the affected skin areas and an anti-inflammatory like prednisone to take orally.

Over the counter remedies include antihistamines like Benadryl or anti inflammatory pain relievers like Advil, Motrin or Aleve. In milder cases oatmeal products or calamine lotion may provide some relief from the itching as will after bite, apple cider vinegar or witch hazel. All in all the symptoms take between 2 and 4 weeks to go away, depending on how bad a case you got. If it is persisting chances are you are being re-infected.

The amazing thing about urushiol is that it can remain allergenic on clothing for up to 10 years! Crosbie J. 2020

If you have inhaled the smoke from burning poison sumac or ingested this plant you will likely be making a trip to the hospital as the smoke can cause inflammation and painful sores in the lungs and cause them to fill up with fluid. Ingesting this plant can cause painful sores in the gastrointestinal tract.

Other Plants That Contain Urushiol

Poison ivy and poison oak are the two other most notable plants that contain urushiol. Surprisingly pistachios, cashews and mango also contain urushiol.

How Can You be Sure Your Reaction Is To Poison Sumac And Not Poison Oak Or Poison Ivy?

If you did not actually see the plant you will not be able to differentiate the specific plant you brushed up against by the rash it produces, other than perhaps the thin red lines caused by the sharp edges of poison ivy. The reaction and treatment are the same for all three of these plants and thus it really doesn’t matter. Having said that though poison sumac only grows in swampy, boggy areas and poison ivy and poison oak are more typically found in dry woodlands.

How To Get Rid of Poison Sumac Plants?

It is not common for poison sumac to grow in residential yards. If you happen to live in one of the few areas where it does grow make sure you have properly identified the plant as the non-toxic sumac varieties are often mistaken for poison sumac.

Before attempting to remove poison sumac plants be sure to wear the proper protective clothing; close-toed shoes or boots, long pants, long sleeved shirt, water proof gloves and ideally face and eye protection. Do not touch your face or any bare skin with your gloved hand. Also try not to touch the surface of anything other than the tools you are working with. When you have finished removing the poison sumac wash your tools and any surface you may have touched. Wash your shoes and shoelaces off and change and wash your clothing.

Physical Control:

Remove all the stems from the tree/shrub and black bag them. Label the bag poisonous plants material. As mentioned earlier do NOT burn them. Next cut the trunk down and dig the stump. Try to collect as much of the root as you can as they can sprout new plants. Monitor the area regularly for new sprouts, and remove any found. If new seedlings are still very young you may be able to pull them.

Chemical Control:

Using a systemic herbicide like round-up is most effective when the plants are young or in spraying new shoots that are arising from bits of root that were left behind from the physical removal of the plant.

Summary

Poison sumac while rare is not a plant you want to be touching with bare skin. If you happen to live near a boggy or marshy area, in a region where the plant grows, make sure you are able to identify the plant and stay vigilant when you are out on nature trails.

Poisonous to Touch Weeds Covered in This Series Include:

  1. Poisonous to Touch Weed Series: Poison Ivy (Toxicodendron radicans and Toxicodendron Rydbergii)
  2. Giant Hogweed (Heracleum mantegazzianum)
  3. Cow Parsnip (Heracleum maximum)
  4. Wild Parsnip (Pastinaca sativa)
  5. Poison Sumac (Toxicodendron vernix)
  6. Poison Oak (Toxicodendron diversilobum) and (Toxicodendron pubescens)

Other Poisonous to Touch Plants Not Covered in This Series Include:

  1. Poke Weed (Phytolacca decandra): besides being mildly to highly toxic this plant can cause a rash in sensitive individuals.
  2. Stinging Nettle (Urtica dioica): the leaves and young stems of this herbaceous plant are fitted with stinging hairs tipped with formic acid and other irritants. If touched, these needle-like hairs inject the stinging acid into the skin, triggering a burning, tingling sensation and an itchy rash. Thankfully the symptoms usually do not persist longer than 24 hours.
  3. Monkshood (Aconitum napellus): This is a highly toxic plant. The neurotoxins, aconitine and mesaconitine can be absorbed through the skin and cause severe respiratory and cardiac problems. So do not pick or handle this plant without gloves, especially by the root.
  4. Oleander (Nerium oleander): This is a highly toxic plant. The gummy sap can cause skin irritation or possibly dermatitis in those who are sensitive. If you are growing this plant as an ornamental in your garden be sure to were gloves, long sleeves, long pants, closed shoes and protective eye wear before pruning this plant.
  5. Bloodroot (Sanguinaria canadensis): the flower of this plant produces a reddish toxic sap that looks very similar to blood and contains the toxin sanguinarine. If this sap comes in contact with bare skin it can cause burning. If you get a high concentration of sap on your skin it can even eat away the flesh. If ingested, it is deadly to animals.
  6. Wood Nettle (Laportea canadensis): like stinging nettle have stinging hairs along its stem.

References

Cafasso J. rev. Sept. 2018. Medically reviewed by Sarah Taylor, M.D., FAAD. Identifying and Treating a Poison Sumac Rash. Retrieved on Mar. 10, 2021 from: Poison Sumac: Rash, Pictures, and Treatment (healthline.com)

Crosbie J. 2020 (updated) D.O.August 5, 2019, Des Moines University, Retieved on Jan. 31, 2021 from: Everything you need to know about poison ivy | News | Des Moines University (dmu.edu)

Gov. of Canada 2016 (modified). Poison Ivy. Retrieved on Jan. 31, 2021 from: https://www.canada.ca/en/health-canada/services/home-garden-safety/poison-ivy.html

Lofgran T. and Mahabal G. rev. Feb. 2021. Toxicodendron Toxicity. Retrieved on Mar. 10, 2021 from: Toxicodendron Toxicity – StatPearls – NCBI Bookshelf (nih.gov)

Minnesota Wildflowers n.d. Toxicodendron vernix (Poison Sumac), Retrieved on Mar. 10, 2021 from: Toxicodendron vernix (Poison Sumac): Minnesota Wildflowers

Natural Resources Canada rev. 2015-08. Poison-sumac. Retrieved on Mar. 10, 2021 from: Poison-sumac (nrcan.gc.ca)

N.C. Cooperative Extension n.d. Toxicodendron vernix. Retrieved on Mar. 10, 2021 from: Toxicodendron vernix (Poison Sumac, Swamp Sumac, Thunderwood) | North Carolina Extension Gardener Plant Toolbox (ncsu.edu)

Tec Labs n.d., Retrieved on Jan. 31, 2021 from: Where to Find Poison Ivy, Oak & Sumac | Tec Labs (teclabsinc.com)

Other resources:

All About the Sumacs—Good or Bad – The New York Times (nytimes.com)

P­oison Ivy, Poison Oak & Poison Sumac | Safety Information Site (ualberta.ca)

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