Juglans cinerea aka White Walnut

Butternut, Juglans cinerea, is a deciduous tree in the walnut family. It also goes by white walnut, oil nut and lemon nut. It is native to eastern Canada and the central and eastern United States. Its range runs from New Brunswick south to Georgia and west to the Dakotas and Arkansas. In the wild it grows in moist bottomlands, along riverbanks and on some drier limestone soils.

In gardens it reaches 40 to 60 feet (12 to 18 m) tall and 30 to 50 feet (9 to 15 m) wide. Forest trees can top 100 feet (30 m). The crown is open, rounded and spreading, with stout, heavy branches. The trunk is often short, forked or crooked. Most trees live about 75 years.

Young bark is smooth and gray with pale lenticels. With age it develops flat, pale ridges in a diamond pattern, separated by dark furrows. The leaves are pinnate and 10 to 20 inches (25 to 50 cm) long. Each carries 11 to 19 serrated, lance-shaped leaflets with soft hairs. The leaf stalks are sticky and hairy. Leaves turn yellow in autumn. The twigs have a chocolate-brown, chambered pith and a hairy pad above each leaf scar.

The tree carries male and female flowers separately, from April to June. Males hang in yellow-green catkins up to about 5 inches (12 cm) long. Females form short spikes at the shoot tips, with bright red stigmas. Neither is showy. The fruit is an oblong nut in a green husk covered in sticky hairs. It ripens in September or October. The kernel is sweet, oily and mild, but it turns rancid quickly. The shell is hard to crack. For a good nut crop, plant more than one tree for cross-pollination.

Give butternut full sun and deep, fertile, moist soil with good drainage. It grows fast on good ground but slowly on dry, alkaline soil. It dislikes shade and competition. Established trees cope with drought and resist rabbits. The tree is hardy to USDA zone 3 and rated H6 in the UK. It suits parks, large gardens and edible or wildlife plantings. Squirrels, birds and other animals eat the nuts. The leaves feed caterpillars of the luna moth and hickory horndevil. People have used the wood for furniture and carving, and the husks for a yellow to orange dye.

Butternut canker is the main threat. This fungal disease kills most infected trees, has no cure, and has wiped out many wild stands. Other pests include borers, nut weevils, lace bugs, bark beetles and the butternut curculio. Aphids, leaf spot, honey fungus and coral spot can also occur. The roots release juglone, which harms tomatoes, azaleas, rhododendrons, peonies and similar plants nearby. The falling fruit is messy, and the husks stain skin and clothing. The bark has a laxative effect, and its compounds may irritate the stomach.