Beginners at plant identification can easily confuse poison sumac and non-rash-causing types of sumac such as staghorn sumac. Indeed, the plants are related. Moreover, they both are tall shrubs (sometimes reaching about 30 feet tall), deciduous, and native to eastern North America. Most strikingly, they share a trait that draws much attention to them in autumn: extremely colorful fall foliage.
Despite these similarities, it is important to appreciate their differences. Knowing how to tell poison sumac apart from staghorn sumac could save you from getting a terrible skin rash. You can get the rash by coming into contact with poison sumac at any time of year, including winter. By contrast, the only warning to issue about staghorn sumac is that, if you want to grow it on your land as a shrub to give you great fall color, be aware that it can spread out of control via its underground rhizomes.
Fortunately, learning a little about the plants' respective habitats and the differences in their leaves, twigs, and berries will help you arrive at a positive identification and allow you to enjoy a walk in the woods with greater peace of mind.
Family Ties Between Poison Sumac and Staghorn Sumac
Poison sumac and staghorn sumac belong to the same family: Anacardiaceae. This botanical group is also called the "cashew" family, and cashew trees (Anacardium occidentale) are part of it. If it surprises you that rash-causing poison sumac has family ties with a plant that bears edible nuts, be prepared to be surprised again: Mango trees (Mangifera spp.) belong to the same family. Another beneficial plant in the family is the smoke bush (Cotinus coggygria), a popular ornamental landscape plant.
When we take a closer look at the botanical classification of poison sumac and staghorn sumac, however, we see how scientists have drawn a distinction between them: They belong to different genera. Whereas poison sumac is known to botanists as Toxicodendron vernix, staghorn sumac is classified as Rhus typhina. The very genus name of poison sumac indicates its toxic nature. Poison sumac is actually more closely related to two other rash-causing plants than it is to staghorn sumac:
How to Tell Poison Sumac and Staghorn Sumac Apart
Realizing that these two plants usually are found in quite different habitats is step one in distinguishing between them. Poison sumac is a plant of very wet areas. If you do not spend any time around swamps, there is a good chance that you will never see poison sumac, even if you visit a region to which it is native, such as New England (U.S.).
By contrast, if you visit New England in autumn to view the fall foliage, it would be difficult to avoid seeing staghorn sumac. It is a frequent inhabitant of stretches along the roadside where the soil is dry. Because it spreads to form massive colonies, you usually do not see a single plant standing alone. This gives us another contrast with poison sumac, a solitary specimen of which you may very well find growing in a swamp.
But there are also a few identification features that you should know to help you tell the two plants apart (at least at certain times of the year). The berries (drupes) provide the most obvious clue. Poison sumac sports groups of separate berries (not fused together) that droop down from small stems. The shape of the berries is flattish. They mature to an off-white color in the fall. But the berries of staghorn sumac are red. They are packed tightly together in soft, cone-shaped tufts that grow upright.
But the plants will have leaves for more months of the year than they will have berries, and they will have twigs (the youngest branches) year-round. So learning the differences between their leaves and twigs is even more helpful. Both poison sumac and staghorn sumac have compound leaves, made up of individual leaflets. Happily, their leaves differ in a few ways, so you should have no trouble telling them apart; while, even in winter (when there are no leaves), you can tell the two apart by inspecting their twigs:
- The leaflets of poison sumac have smooth margins; those of staghorn sumac are toothed.
- A staghorn sumac leaf will have at least 13 leaflets on it (usually more); a poison sumac leaf will have at most around 13 leaflets (usually fewer).
- The twigs on poison sumac are smooth; those on staghorn sumac are covered in tiny hairs.