American smoke tree is a tall shrub to small tree usually 6–16 feet tall, with slender, spreading branches and aromatic, resinous sap. It may attain a height of 33 feet.
Leaves are simple, alternate, most abundant toward the twig tips, 1½–6 inches long, 2–3½ inches wide, broadest in the middle and tapering at both ends, or obovate (egg-shaped with the narrow part at the base); tip round to blunt, base broadly wedge-shaped or rounded, margin entire or somewhat wavy; upper surface bluish green or olive green and smooth to hairy; lower surface hairy early and smooth with age, veins conspicuous; leaf stalk ¼–2 inches long, yellowish green to reddish, smooth or hairy; bruised leaves somewhat fragrant.
Bark is gray to black, roughly breaking into thin scales that are longer than broad; wood orange to yellow, sapwood creamy white, coarse-grained, soft, light.
Twigs are slender, green to reddish or purple when young, gray and smooth with age; pores small, abundant, pale.
Flowers in May, greenish yellow, borne in loose, few-flowered clusters at the end of stems, clusters 5–6 inches long, 2½–3 inches broad; flower stalks with feathery, gland-tipped hairs and purplish flowers about ⅛ inch across, petals 5; stamens 5. The “smoke” from smoke tree is often mistaken for a spray of flowers, but what you are seeing is actually the hairy, colorful stalks of the flowers after the blossoms have fallen away.
Fruits June–July, small, hard-cased drupes (a seed covered by fleshy pulp) ⅛–¼ inch long, kidney-shaped, flattened, smooth, pale brown; fruit stalk slender, conspicuously purple or brown with gland-tipped hairs.
Similar species: The Eurasian smoke tree (Cotinus coggygria) is commonly sold in garden centers as a landscaping ornamental. It is not native to North America. It is typically smaller, with smaller, more oval leaves and showier flower clusters. At least one popular variety of the Eurasian smoke tree has purplish leaves.
Habitat and Conservation
The brilliant orange and red colors of the leaves in autumn make smoke tree a worthwhile ornamental. Use it in masses or as part of a shrubby border planting. It can also be striking on its own as an accent tree. Horticulturists have been developing special cultivars especially for landscaping purposes. Most smoke trees sold at nurseries, however, are the nonnative Eurasian smoke tree, C. coggygria.
Smoke tree is called “yellowwood” by some, although that name is more correctly applied to another tree, Cladrastis kentuckea. Both plants have been used to make a yellow dye. Smoke tree was so heavily used for yellow dye during the Civil War period that its numbers declined precipitously.
Smoke tree wood is also very durable in contact with the soil and has been used for fence posts.
The genus name, Cotinus, is the Latin name for “olive”, even though this plant is not related to olives. The species name, obovatus, refers to the leaf shape — obovate — an upside-down, two-dimensional egg shape.
Another common name for smoke tree is chittam-wood. The same name is used for black haw (Sideroxylon) and various buckthorn (Bumelia) species, too — but what does it mean? Apparently the close-grained, yellowish wood of these North American trees seemed similar to the wood of a tree mentioned frequently in the Bible. The biblical tree, called the shittah in Hebrew (shittim is the plural version), is a type of acacia native to the Middle East. In some Bibles, it’s called the shittah tree, but it’s translated to English “acacia” in others. Besides being a clearer translation, calling it “acacia” might also prevent some snickering or blushing in the congregation. Among many uses of shittah wood mentioned in the Bible, the Hebrews’ Ark of the Covenant was said to be made of that type of acacia. Acacias are in the bean family and are not related to smoke tree or to buckthorns.
Smoke tree is in the same family as cashew, pistachio, mango, sumacs, and poison ivy.
Smoke tree and other small trees provide important cover and nesting habitat for birds and other wildlife.
Finches and other birds and small mammals eat the fruits and help disperse seeds to new locations.
Apparently white-tailed deer do not feed heavily on smoke tree foliage.
Recently, researchers studying American smoke trees in the Ozarks noticed leaf-mining caterpillars eating S-shaped tunnels into the middle tissues of the leaves. These little caterpillars grew up into rusty-brown moths with narrow white bands on the wings. The wingspan of these small moths is about ¼ inch. The researchers noticed that these moths closely resemble a species called the poison ivy leafminer, a leaf blotch miner moth whose larvae feed on fragrant sumac and poison ivy, which are in the same family as smoke tree. But the reproductive organs of the adult smoke tree moths didn’t match those of the poison ivy leafminer, so the two nearly identical moths could not reproduce together. It turned out the researchers had discovered a new species of moth. In the 2016 paper describing the new species, they named it Cameraria cotinivora: the species name, cotinivora, means “Cotinus (smoke tree) eater.” This moth species has been found only in three counties in north-central Arkansas and in Ozark County, Missouri, on the state’s southern border. You can bet naturalists will be looking to see if it occurs elsewhere, too.
At least one other moth species uses smoke tree as a larval host: the spotted datana (Datana perspicua), a prominent moth that feeds on sumacs as well.