Sumac refers to flowering plants within the genus Rhus, part of the cashew and mango family, Anacardiaceae. The plant is widely distributed across subtropical and temperate regions globally. While many species are valued for their ornamental beauty or culinary uses, the name “sumac” is often associated with a dangerous irritant. This confusion stems from the historical classification of toxic species alongside harmless varieties, making clear identification essential.
Identifying Characteristics
Non-poisonous sumac species, often referred to as “True Sumac,” grow as deciduous shrubs or small trees. A defining feature is their compound leaves, which are usually pinnately structured, meaning leaflets grow in pairs along a central stem. The edges of these leaflets are typically serrated or toothed, which helps distinguish them from toxic look-alikes.
The most recognizable feature is the fruit, which forms dense, upright, cone-shaped clusters at the tips of branches. These small, reddish drupes can be fuzzy or smooth and often persist through winter. Species like the Staghorn Sumac (Rhus typhina) are named for the velvety texture of their branches and fruit. The foliage of these varieties provides striking visual interest in the fall, turning brilliant shades of red and orange.
The Critical Distinction: Safe vs. Poison
The distinction lies between safe Rhus species and Poison Sumac, which is now classified in a separate genus, Toxicodendron vernix. This reclassification highlights the major biological difference, yet the common name still links the two, necessitating careful visual identification. The danger of Poison Sumac is due to urushiol, a resinous oil that causes a severe delayed allergic reaction upon contact.
Visual cues are the most reliable method for distinguishing the two. True Sumac plants feature dense, red clusters of fruit that stand erect at the end of the branch. Conversely, the fruit of Poison Sumac is grayish-white or creamy and hangs in loose, drooping clusters.
Another clear differentiator is the leaf structure and location of growth. True Sumac varieties have serrated leaflets. In contrast, Poison Sumac leaflets are smooth with untoothed margins. Poison Sumac also has a specific habitat preference, almost exclusively growing in wet, waterlogged soils such as swamps and bogs, whereas True Sumac is often found in drier, disturbed areas. All parts of the Poison Sumac plant contain urushiol and remain toxic even after the plant has died.
Practical Uses and Cultural Significance
The non-poisonous species of sumac have been utilized by humans for centuries, offering both culinary and practical value. The tart, lemony flavor of the dried and ground drupes is a result of high concentrations of malic acid, making it a popular spice in Middle Eastern cuisine. This reddish-purple powder provides a bright, acidic tang to dishes where it is used as a garnish or a primary ingredient in spice blends like za’atar.
Indigenous peoples in North America also traditionally used the fruit of native species, such as Staghorn Sumac, to create a refreshing beverage. By steeping the drupes in cool water and straining the mixture, a drink commonly called “sumac-ade” or “pink lemonade” is produced. Beyond consumption, various parts of the True Sumac plant have been employed as natural dyes, yielding colors that range from red to black. Many varieties are also incorporated into landscaping for their robust growth habit, tolerance for poor soils, and their vivid fall color.