Family: Juglandaceae, walnut family
Genus, species: Juglans nigra
Leaves are pinnately compound, with a feathery appearance, more delicate-looking compared to ash leaves. Each leaf has 14 to 24 leaflets. Largest leaflets are located in the center of the leaf. Leaflets are lance-shaped, finely saw-toothed.
Bark is dark brown, deeply furrowed.
Male and female flowers are separate but in same tree (monoecious), clustered in catkins.
Fruit is very hard, covered by thick green husk. Husk produces a dark-staining, strong-smelling juice. Green husk of fruit has been used to make a blackish dye since colonial times. Nuts are edible. Before eating or storage, nuts should be cured in a dry place for at least two weeks.
Black walnut produces juglone and releases it through its roots. Juglone is a chemical that is toxic (allelopathic) to some nearby competitor plants. Juglone causes wilting or yellowing of foliage of neighboring plants.
Juglans is from the Latin for "walnut" and nigra is from the Latin for "black."