Black Walnut Juglans nigra

Juglans nigra, commonly known as Black Walnut as the nuts and husks can make a dark stain, is an extremely valuable and attractive forest tree. It is a member of the walnut family (Juglandaceae) and is native to a broad swath of central and eastern North America. It grows well on rich bottom lands, in moist, fertile coves, and on lower slopes throughout North Carolina. The species epithet is Latin for "black."

Black Walnut prefers moist, organically rich, well-drained soils in full sun. It prefers full sun and wet to dry loam or sandy high acidic to slightly alkaline soil. Its survival, growth, and quality in less fertile sites is problematic. It is intolerant of shade. 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. It may be grown for its edible nuts. Nut production can sometimes begin as early as 6 years but usually takes 20 years for a substantial crop. 

Its tree's leaves, stems and roots contain juglone, which inhibits the growth of some plants beneath the tree's dripline. Plants known to be sensitive to juglone include azaleas, peonies, and some fruits and vegetables, like tomatoes, apples, and blueberries,  

The nuts are edible but difficult to remove from the husk, and the fleshy husk can be used as a dye. 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.