Juglans cinerea, commonly known as butternut or white walnut, is a species of walnut native to the eastern United States and southeast Canada.The Butternut tree’s range extends from the New England states southward to northern Georgia and Alabama, and westward to Minnesota, Iowa, Missouri, and Arkansas. It is absent from most of the Southern United States. In Canada, it’s found in parts of Ontario and Quebec, particularly in the southern regions where the climate is more temperate.
When Europeans arrived in North America, they quickly adopted the use of Butternut for its timber and nuts. The wood, being soft and easy to work with, was favored for carving and furniture making. Butternut was not just a forest tree but also found its way into orchards and agricultural landscapes. Its nuts were a minor but appreciated crop, and its wood was valued in carpentry and cabinetry.
Mature Butternut trees typically reach heights of 40 to 60 feet, though under ideal conditions, they can occasionally grow taller. These trees have relatively fast growth in their youth, especially when planted in optimal conditions. The leaves are pinnately compound (they have leaflets arranged along a central stem (rachis).The whole leaf is downy-pubescent, and a somewhat brighter, yellower green than many other tree leaves. In the fall, they turn a golden yellow to brown before falling.
Flowers are monoecious (have both male and female flowers on the same tree). Male flowers are borne in catkins, which are long, slender, hanging structures. They are typically a yellowish-green to brownish color. Female flowers are much less conspicuous, forming in small, erect clusters near the tips of new shoots. Each female flower is tiny, with a greenish hue. After successful pollination, the female flowers develop into the fruit, which is the butternut itself, enclosed in a husk that matures over the summer.
They can grow 1 to 2 feet per year during their first few decades. As they age, the growth rate slows down. However, even mature trees can still add significant height and spread each year if conditions remain favorable. Under natural conditions without disease, Butternut trees can live for 75 to 100 years. Some exceptional specimens might live longer if they remain healthy.
The bark is generally a light gray to brownish-gray hue, which can darken with age or exposure. On younger trees or branches, the bark is smoother but still shows signs of vertical fissures. As the tree matures, the bark becomes deeply furrowed. It develops into a pattern often described as “wagon-rut” or “tire-track” like, with deep, vertical grooves and ridges. Historically, the bark was used for dyeing due to its rich color when boiled. Native Americans and early settlers used it to create a brown dye.
Butternut trees develop a taproot system when young. This taproot can grow deep into the soil, providing stability and access to deeper water sources. In their early years, Butternut trees focus on developing a strong taproot. However, as they mature, this taproot system transitions into a more complex structure. Mature Butternuts develop a lateral root system in addition to the taproot. These lateral roots spread widely, often extending beyond the canopy’s drip line, which helps in anchoring the tree and accessing a broader area for nutrients and water.
The nut is oval to elliptical in shape. It’s enclosed in a thick, green husk that turns brown and splits open when ripe, revealing the nut inside. The shell is thick and deeply furrowed, which makes it somewhat challenging to crack open but also gives it a distinctive appearance.
Butternut grows best on stream banks and on well-drained soils. It is seldom found on dry, compact, or infertile soils. It grows better than black walnut, however, on dry, rocky soils, especially those of limestone origin. Butternut’s range includes the rocky soils of New England where black walnut is largely absent.
Butternut is found most frequently in coves, on stream benches and terraces, on slopes, in the talus of rock ledges, and on other sites with good drainage. It is found up to an elevation of 1,500 metres (4,900 ft) in the Virginias – much higher altitudes than black walnut. The nuts are eaten by wildlife. Although young trees may withstand competition from the side, butternut does not survive under shade from above. It must be in the overstory to thrive.
Butternut is critically endangered due to a fungal disease called Butternut canker (Ophiognomonia clavigignenti-juglandacearum). This disease causes cankers on the bark, leading to dieback and eventually death of the tree. Diseased trees usually die within several years. Completely free-standing trees seem better able to withstand the fungus than those growing in dense stands or forest. In some areas, 90% of the butternut trees have been killed. The disease is reported to be spreading rapidly in Wisconsin. By contrast, black walnut seems to be resistant to the disease. Conservation efforts are ongoing, including breeding resistant strains.
Ecological Role
- The nuts are a food source for wildlife, including squirrels, chipmunks, and various birds.
- Like other walnut species, Butternut can produce juglone, a substance toxic to some plants, which affects what can grow near it.
Challenges
- Disease Spread: The Butternut canker has spread across most of the tree’s range, leading to a drastic reduction in its numbers. This disease affects the tree’s ability to reproduce and survive, leading to fragmented populations.
- Habitat Loss: Urbanization, agriculture, and changes in land use have also contributed to the loss of habitat for Butternut trees.
- Climate Change: Future climate changes might further alter the suitable habitat for Butternut, potentially pushing its range northward or to higher elevations.
Uses
- It’s used for furniture, cabinetry, and detailed carvings due to its softness and the way it takes finishes well.
- It’s also used for interior paneling, doors, and moldings because of its attractive appearance and workability.
- Butternut nuts are rich in oils, proteins, and vitamins. They can be eaten raw, roasted, or ground into meal. The nuts are larger and sweeter than black walnuts, making them a favored snack.
- Historically, the bark was used as a purgative or laxative. It contains compounds like juglone, which have medicinal properties.
- Early settlers in North America also relied on butternuts for food during times of scarcity.
Nutritional Value:
- High in Fats: Butternuts are rich in healthy fats, particularly omega-3 fatty acids.
- Protein and Vitamins: They contain significant amounts of protein, fiber, and vitamins like vitamin E, which is an antioxidant.