The genus Juglans, which includes various species of Butternuts and Walnuts, was named by the Swedish botanist, Carl Linnaeus, who developed the modern classification system for plants and animals. He evidently thought well of them, because “Juglans” is the nut of the gods, a combination of Jovis (the god Jupiter) and glans, an acorn or nut. The native Butternut (Juglans cinerea) was never common, and it’s easily overlooked due to the similarity to Black Walnut (J. nigra).
Butternut Leaves
Butternut (not to be confused with Bitternut, a hickory), has leaves very similar to those of Black Walnut. The leaves of both are alternately-arranged, pinnately-compound, and have pinnately-veined leaflets.
Butternut leaves are alternately-arranged, i.e., the leaves and branches are not attached directly across from one another.
Compound leaves have multiple leaflets that share a stem, all of which die off at the end of the year, at least on deciduous trees. The leaflets of a pinnately-compound leaf are attached at different points on the stem’s length, whereas the leaflets of a palmately-compound leaf are attached at a single point.
But it’s important to realize that the individual leaflets on a compound leaf might or might not be directly across from each other. It’s the arrangement of the entire leaves that determines whether a tree is alternate or opposite. Finally, Butternut leaflets are pinnately veined, with secondary veins attached to the central vein at multiple points. Palmately-veined leaves have multiple veins attached at the base of the blade.
Butternut leaves are typically up to 24 inches long, with 11 to 17 pointed, lance-like leaflets 2 to 4.5 inches long. The undersides of leaves are often hairy. The leaves are very similar to Black Walnut, except that Butternut leaves usually have a single leaflet at the end, while Black Walnut leaves have two. Black Walnuts also typically have a few more leaflets. Butternut leaves, like Black Walnut leaves, turn yellow or brown in the fall.
Butternut Flowers
Butternut flowers appear in early spring and consist of green catkins. Dioecious trees have male and female flowers on separate trees. Butternut is monoecious, with male and female flowers on the same tree. Obviously, dioecious trees can’t pollinate themselves, but many monoecious trees also have strategies to prevent self-pollination.
Butternuts prevent self-pollination by having male, pollen-producing flowers that mature at different times than the female, seed-producing flowers on the same tree. And as is often the case with green, un-showy flowers, Butternuts are wind-pollinated. Insect- and bird-pollinated trees more often develop bright flowers to attract pollinators.
Butternut’s pollinated flowers develop into 1.5 to 2.5-inch nuts in late summer, similar to Black Walnuts, but smaller and more elongated. The fruits have a pair of brain-like meats, surrounded by a rugged, woody shell, covered by a thick green skin. Unlike Black Walnuts, Butternuts often have four ridges, and they tend to be hairy and sometimes sticky. Butternuts, as the name suggests, are very oily, and they were commonly pressed for oil. Butternuts begin producing seeds at around 20 years of age and produce good crops every 2 or 3 years.
Butternut Bark
Butternut bark is rugged, but generally less so than BlackWalnut, and somewhat lighter in color. In fact, Butternut’s species name, cinerea, means “gray”. Butternut and Black Walnut twigs, cut lengthwise, have small, evenly-spaced dividers in the center, forming “chambered pith”. The chambers might help regulate the flow rate of sap.
In the absence of leaves, the most obvious difference between Butternut and Walnut is in the leaf scars. Black Walnut leaves have a distinctive scar, often described as a “monkey face”. Butternut leaf scars are similar, but the monkey’s “eyes” are usually farther apart, making the monkey face more T-shaped. Butternut also has hairy fringes above the leaf scars on young twigs.
Identification Summary
Butternuts have a typical height of 40 to 70 feet, and a trunk diameter of 1 to 2 feet – somewhat smaller than Black Walnut, which has a height of 70 to 90 feet at maturity. The Ohio Champion Butternut, located in Portage County, has a height of 79 feet, a trunk diameter of 6.6 feet, and a crown width of 85 feet. One reason for Butternuts’ small size is that their lifespan is only about 75 years.
ID Summary: Smallish tree with 11-17 lance-shaped, toothed leaflets, one of which is at the end of the 1.5- to 2-foot, pinnately-compound leaf. Nuts more elongate than Black Walnut, and often ridged. Chambered pith and “monkey-face” leaf scars with widely-separated “eyes”.
Similar Trees: Closest to Black Walnut, but with one leaflet at the end of the leaf, while Walnut has two. Leaves resemble Ailanthus Tree of Heaven, but the latter’s leaflets have only a few teeth near the stem, and Ailanthus lacks chambered pith. Butternuts hybridize with some non-native walnuts, but apparently not native Black Walnut.
Habitat
Butternut lives in moist but well-drained soils, often on slopes near creeks, in areas with available sunlight. Butternut prefers somewhat cooler climates than Black Walnut, and is not found in the southernmost U.S. Butternut usually does not occur in pure stands.
Butternut’s close relative, Black Walnut, is famously allelopathic, and produces toxic juglone (named for the genus Juglans), which kills many surrounding plants to reduce competition. Butternut also produces juglone, but in lower concentrations. The Hickories (genus Carya) also produce some juglone, and all are in the family Juglandaceae. But in fact, many other trees are also allelopathic.
The Penn State Extension website informs us that, “Many plants (e.g., sugar maple, tree of heaven, hackberries, sycamore, cottonwood, black cherry, red oak, black locust, sassafras, fine fescue, and American elm) produce allelochemicals to enhance their survival and reproduction by inhibiting nearby competition.” (The Penn State site also has an extensive list of plants that are tolerant of juglones). Juglone has low water solubility and doesn’t typically move very far beyond the tree’s dripline. But juglone’s chemical stability and low solubility mean that it can persist in soil years after a tree is removed.
Butternuts were never very common, but their numbers are dwindling, due to Butternut canker, which they were exposed to early in the twentieth century. Fortunately, Black Walnut appears to be resistant, as is Japanese Walnut, with which Butternut hybridizes. The resulting “buartnuts” are canker-resistant, and it’s possible that no pure native Butternuts remain.
Some long-lived trees, such as White Oak (Quecus alba), potentially predate the introduction of Eurasian trees, and are genetically pure. But Butternut’s 75-year lifespan means that none predate the introduction of non-natives, and all of them might be hybrids. Butternut hybrids have a notch at the top of the leaf scar.
Lucy Braun’s The Woody Plants of Ohio shows Butternut occurrences in most of Ohio’s eastern counties, but only sporadic occurrences in the western ones. The Columbus, Ohio Street Tree Inventory does not list Butternut among its 80 most common trees.
Lumber
Butternut lumber has a Janka hardness of 490 lbf and a density of 0.43 g/cc, according to the Wood Database, compared to the median of my list of 73 Ohio trees of 1,075 lbf and 0.64 g/cc. Butternut is substantially softer and lighter than Black Walnut, whose hardness is 1,010 lbf and density is 0.61 g/cc. Their grain patterns are similar, but Butternut lacks Walnut’s distinctive brown color. In fact, I’ve heard that scammers used to dye Butternut and sell it as Walnut.
But with Butternut’s current scarcity, some scammers bleach Walnut and sell it as Butternut! (They say love finds a way, unfortunately, so does money). Butternut, like Walnut, is durable (rot-resistant), but Walnut is more so, as is typical of darker woods. Butternut works well, and is a favorite for light furniture and carving.
Butternut Uses
The thick green skin covering Butternut fruits was once used to dye homespun cloth. The dye was sometimes used on the uniforms of Confederate soldiers, and the men were derisively known as Butternuts. Like Walnuts, the skins and crushed nuts were sometimes thrown into water to stun fish, enabling people to scoop them up.
Butternut’s allelopathy and its susceptibility to canker limit its usefulness in landscaping, despite its attractiveness and modest size that would fit many landscape settings.
According to the Native American Ethnobotany Database, numerous peoples used Butternut meats as food, and bark and roots to make a brown or black dye. Additional uses include:
- Antidiarrheal. Infusion of bark taken to check bowels – Cherokee,
- Cathartic from inner bark – Cherokee, Chippewa, Iroquois, Malecite, Menominee, Meskwaki, Micmac, Potawatomi,
- Toothache remedy – Cherokee, Iroquois,
- Analgesic – Iroquois,
- Worm removal from decoction of bark – Iroquois,
- Blood purifier and for venereal disease from decoction – Iroquois,
- Bleeding wounds treated with infusion of bark – Iroquois,
- Nut-meat oil used for the hair – Iroquois,
- Compound decoction with bark taken to induce pregnancy – Iroquois,
- Laxative from decoction of bark or shoots – Iroquois,
- Poultice for infected and swollen tubercular glands – Iroquois,
- Gynecological aid from roots or bark – Iroquois,
- Insecticide from nut oil, mixed with bear grease for mosquitoes – Iroquois.
Butternuts are edible, and have long been popular in New England for a candy made with maple sugar. The immature nuts were also once pickled while the shells were still soft, and eaten whole. Butternut sap can be boiled to make a sweet syrup, but the sugar content is only a quarter as high as that of Sugar Maple. And, as the common name, “oil nut” indicates, the nuts were a major source of a butter-like oil. However, butternuts must be harvested and dried, pickled, or otherwise treated soon after harvesting, or they become rancid.
The Botanical.com website lists constipation, dysentery, syphilis, ulcers, and tapeworm as medical conditions that have been treated with Butternut. According to the Peterson Field Guide to Medicinal Plants and Herbs, juglone also has antiseptic and, perhaps, antitumor properties. Rebecca Rupp’s Red Oaks and Black Birches tells us that the bark from J. cinerea roots was listed in the United States Pharmacopeia from 1820 to 1905 for use as a laxative. Rupp also indicates that at peak ripeness, Butternuts contain as much as 60% of their mass in oil.
Squirrels and other rodents, birds, and various mammals eat the nuts. Wood borers, nut weevils, lace bugs, bark beetles, and butternut curculio are potential pests that feed on Butternut.
Walnut trees are very recognizable. Look for the single terminal leaf, and you’ll occasionally find the far less common Butternut.
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You can also listen to my talks on Ohio Broadleaf Tree Identification on YouTube, Part 1 and Part 2.
