Black Walnut Juglans nigra

Juglans nigra, commonly known as Black Walnut as the nuts and husks can stain, is an extremely valuable and attractive forest tree. It prefers full sun and wet to dry loam or sandy high acidic to slightly alkaline soil. It grows well on rich bottom lands, in moist, fertile coves, and on lower slopes throughout North Carolina. Its survival, growth, and quality in less fertile sites is problematic.

Black Walnut prefers moist, organically rich, well-drained soils in full sun. It is intolerant of shade. It may be grown for its edible nuts. Although young trees sometimes begin producing nuts when only 4 to 6 years old, it usually takes 20 years before a tree will produce a large crop of nuts. The tree is recognized by a 3-lobed leaf scar resembling a monkey face and the furrowed trunk bark. Its roots contain juglone which inhibits the growth of some plants such as azaleas, peonies, some vegetables like tomatoes, apples, and blueberries beneath the tree's dripline. This massive tree with a 50 to 90 foot height and a 3 to 6 foot diameter trunk when mature. It has an upright spreading open form, with an ovid crown and a tall trunk, and very deep taproot making it difficult to transplant.  It has the habit of losing its lower branches to begin its spread at 20 feet above the ground.  Both male and female flowers are on each tree (monoecious); males take the form of 2 to 4 inch long catkins with 17 to 50 stamens and female flowers forming on the end of stalks bearing fruit in October. Nut production can sometimes begin as early as 6 years but usually takes 20 years for a substantial crop.  The fruits are both edible and used as a dye, though difficult to remove from the fleshy husk.  Once used by Native Americans medicinally, the tree is a scarce, native hardwood used in furniture and veneer.

Diseases, Insects, and Other Plant Problems:

Under pressure in some areas from thousand cankers disease. Other potential diseases include anthracnose, bacterial blight, root rot, canker, leaf spot and shoot dieback. Watch for aphids, fall webworm and a variety of foliage chewing caterpillars. Nuts can be messy in fall. Occasionally known to cause contact dermatitis in humans.

Habitat: Moist, nutrient-rich forests of floodplains and slopes, calcareous

VIDEO Created by Elisabeth Meyer for "Vegetables, Herbs, Fruits, and Nuts" a plant identification course offered in partnership with Longwood Gardens.