Black walnut is the most valuable tree in Iowa.
The leaves are alternately arranged on the twig, compound with 1 to 23 leaflets, and ranging in size from 1 to 2 feet. The terminal leaflet is either absent or much smaller than the leaflets near the middle of the leaf. Twigs are moderately stout to very stout, gray-green or light brown in color and have a chambered pith which is tan to light brown in color. The bark is dark gray or black, deeply furrowed, with interconnecting ridges that become thick and blocky on larger slow growing trees. Black walnut is native throughout the state.