Juglans nigra is a vigorous, large, deciduous, broad-crowned tree with large pinnate leaves. The tree gets its name from its dark, heavily ridged bark which occurs even when it is still young. Both male and female flowers appear from late May–early June. In autumn, flowers turn to a brownish-green plum-like fruit. The brown nut is held inside this large semi-fleshy husk which is rougher than that of common walnut. The shells are notoriously hard to break; drying them out makes it easier to crush and open the shells.