The butternut is a deciduous tree that naturally grows in America and southeastern Canada. Like other species in the Juglans genus, the butternut is a walnut tree whose seed is a small, commonly eaten nut. They generally grow 40 to 60 feet tall; however, some specimens have been documented at over 100 feet! Unfortunately, wild butternut trees are currently being decimated by disease.
The scientific name of butternut is Juglans cinerea. They are a member of the Juglandaceae family, more commonly known as the walnut family. This family comprises several other trees popularly known for their nuts; among them the hickory, or Carya genus, and pecan, or Carya illinoinensis. Though not all Juglandaceae produce nuts, all—the butternut included—have sizeable, scented leaves. Butternut is also commonly called the white walnut. It is often mistaken for its closest relative the black walnut, which it heavily resembles.
Preferred USDA Hardiness Zones
Butternut grows best in zones three to seven and is native to the upper east U.S. and southern Canada. However, it is a fairly hardy tree that grows as far south as Georgia and can grow in woods or drier, lowland forests. It is often found along streams.
Size and Shape
Butternut trees are generally about 60 feet tall and on occasion grow to over 100. They have fairly wide-spread branches with compound leaves and an open crown of leaves on top. The bark of the butternut is usually gray, but can sometimes be lighter, and their trunks are often crooked.
Foliage, Flowers, and Fruit
Juglans cinerea has bright green, compound leaves that generally grow about 15 to 25 inches. These leaves themselves grow serrated leaflets. The butternut’s foliage turns yellow when its dormant period begins in autumn.
The butternut is monoecious, which means that it grows separate male and female flowers during its bloom in the spring. These flowers are fairly small—only a few inches long—and generally insignificant. Its male flowers are a light yellow-green, while its female flowers are lighter yellow and yield the tree’s namesake edible nuts in the fall.
The butternut grows yellow-green fruit during its bloom that contains nuts encased in husks. These nuts mature throughout the summer and are generally completely mature by the fall. When the husks are cracked, they yield a meaty, edible nut.
These trees need full sun to grow and will not live in the shade; also, they grow best in rich soil with good drainage. Butternuts are commonly used as shade trees, and also can be used to line the sides of roads. They live for decades and can grow to be quite large—generally, butternut planted in any fairly temperate eastern area with well-draining soil will thrive for many years.
In general, butternuts don’t require too much care to survive—the biggest threats to butternuts are diseases, not any problems with growth conditions. As they have become rarer due to disease, it’s fairly uncommon to see butternuts planted by enthusiasts. In the case that they are, the biggest key is to protect them from pests and canker and make sure their soil drains well.
Pests and Diseases
Butternuts are susceptible to multiple insects, including bark beetles, caterpillars, borers, and lace bugs. The grackle also can do damage to butternuts—they eat its fruit.
Butternut canker, a disease spread by fungus, has wreaked absolute havoc on the butternut population to the point that in some areas it has been completely eradicated. There is no cure and trees stricken with the canker generally die within a few years. Early signs of the canker are dead branches and stems, particularly in the tree’s crown; from these branches, the canker spreads to the lower foliage. Though the canker continues to spread, many healthy butternuts still exist—in particular, free-standing trees apart from forests seem less susceptible.