Betula nigra is a deciduous tree that can grow up to 80 feet (24 meters) tall. It has a broad, spreading crown and dark brown to gray bark that peels in curly strips. The leaves are alternate, simple, and doubly serrate. The species is monoecious, meaning that it has separate male and female flowers on the same tree. The male flowers are yellow-brown catkins that hang down from the branches, while the female flowers are upright and green. The fruit is a small nutlet with two wings that is dispersed by the wind.