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How do you identify Poison Sumac?

The Question:
How do you identify Poison sumac?

Submitted by: Ellie, Wilmington, MA

The Short Answer: Poison sumac is a large shrub or small tree found in wet areas. It has compound leaves with 7-13 smooth-edged leaflets, as shown in figure 1. The stalk of the compound leaf is reddish. To differentiate poison sumac from other common sumacs, count the number of leaflets. Staghorn and smooth sumac have more than 13 leaflets, and the leaflets have a serrated edge. Dwarf sumac can have the same number of leaflets as poison sumac, but the leaf stalk has “wings”, as show in figure 3, in keeping with its alternate name, winged sumac.

More Info: Poison sumac, Toxicodendron vernix, is part of the large Anacardiaceae plant family. The Anacardiaceae includes cashew, mango, pistachio, and the “poisonous” plants so painfully familiar to North Americans. Poison sumac is in the same genus as Eastern poison-ivy, Western poison-ivy, Eastern poison-oak, and Western poison-oak, which means it’s closely related to them. They all produce urushiol, the oil that causes such an agonizing allergic reaction. But the plants are probably not trying to irritate your skin. Most likely they produce urushiol to fend off sap-sucking insects. It’s not clear why people are so susceptible to urushiol. Birds and bears eat the berries of poison sumac, poison-ivy, and poison-oak and expose themselves to the leaves with no sign of harm.

Other sumacs such as staghorn sumac, Rhus typhina, are also members of the Anacardiaceae, but don’t necessarily produce urushiol. Poison sumac, while it looks more like harmless staghorn sumac than like poison-ivy and poison-oak, is actually more closely related to its three-leafed poisonous relatives. When biologists use DNA sequences to figure out the relationships between the plants in the genus Toxicodendron, the relationships between Eastern poison-ivy, Toxicodendron radicans, Western poison-ivy, Toxicodendron rydbergii, Eastern poison-oak, Toxicodendron pubescens, and Western poison-oak, Toxicodendron
diversilobum, the relationships are not clear, which suggests that there has been significant hybridization between them over time. This makes it difficult to determine where one species stops and the next begins. In any event, they can all make you miserable, so avoid them if you can.

Trivia:
The cashew plant, Anacardium occidentale, also produces urushiol, and cashews have to be handled and processed carefully to separate the cashew nut from the fruit and remove any urushiol from the nut.

References:

This site is really useful for identifying poison sumac, poison ivy and poison oak:  http://www.poison-ivy.org/poison-sumac

Cite this article as: Pelletier, TC. (June 17, 2010). How do you identify Poison Sumac? Retrieved from http://askanaturalist.com/how-do-you-identify-poison-sumac/ on December 11, 2016.

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9 Responses

  1. Sumac relatives | Makulita Says:

    […] Ask a Naturalist.com » How do you identify Poison Sumac?Jul 17, 2011 … I often hear people referring to these plants as poison sumac, but poison sumac ( Rhus vernix) has white, hairless berries that I can’t imagine … […]

  2. anita cochran Says:

    Whats the best thing to get rid of poison sumac?

  3. Tom of AskaNaturalist.com Says:

    Do you mean to get rid of the plants or get rid of the itching rash?

  4. Lana Jarrett Says:

    I have a red stemmed vine with 5 green leaves in a cluster, has galls on it, growing and sticking around my deck. Is that a poison ivy or sumac?

  5. Tom of AskaNaturalist.com Says:

    Doesn’t sound like poison ivy, since that grows in three leave clusters. Poison sumac is not that common, and mostly grows in swamps. So I think you’re okay. But can you send a photo to tom@askanaturalist.com? Also, where do you live? Poison sumac is only found in the eastern half of the country.

  6. DB Says:

    How can I tell if it’s poison sumac growing near my roses? The pictures look very close. I’ve had many very severe and widespread reactions to ivy and oak, so I don’t want to take a chance removing it myself, if it is indeed sumac. I live in the Northeast United States, and the area it’s growing is very warm and well watered but not swampy. May I send you a picture of the plant?

  7. Tom of AskaNaturalist.com Says:

    Sure. Send your photo to tom@askanaturalist.com, in high resolution, if possible.

  8. George Says:

    I have an acre of property and most of it is wooded. There is poison ivy everywhere in the woods. We have sumac, scrub oak and weeds galore. And part of the property is damp clay swamp. Could some of the small trees near the damp area be poison sumac? The house is in Athens NY in the Hudson Valley. How do i get rid of the plants?

  9. Tom of AskaNaturalist.com Says:

    If you could take some good pictures of the trees you think might be poison sumac, I might be able to tell you. Check the leaf count. If there are more than 13 leaflets on a stem, it’s not poison sumac. As for how to get rid of them, that’s beyond my expertise. If you Google how to remove poison ivy, you’ll get some suggestions. Mostly they involve pulling the plants out by the roots after taking precautions to make sure you don’t expose your skin to the poison ivy oil.

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