Compound leaves with 10 -20 leaflets on a stem. Dark colored bark.
The tree produces an allelotoxin that keeps a variety of other plants from growing near it (Burns and Honkala 1990). The lumber of black walnuts is extremely valuable. It is used to make fine furniture, veneer, gunstocks, paneling, and specialty products. It is also considered to be excellent cabinet wood (Peattie 1964). The nuts are also of value. Not only are they used for food, but the shells have also been used to clean airplane pistons, deburr precision gears, and as filter agents for scrubbers in smokestacks (Burns and Honkala 1990).