Salix nigra, the black willow, is a species of willow native to eastern North America, from New Brunswick and southern Ontario west to Minnesota, and south to northern Florida and Texas.
Salix nigra is a medium-sized deciduous tree, the largest North American species of willow, growing to 10β30 m (35β100 ft) tall, exceptionally up to 45 m (148 ft), with a trunk 50β80 centimeters (20β30 in) diameter. The bark is dark brown to blackish, becoming fissured in older trees, and frequently forking near the base. The shoots are slender and variable in color from green to brown, yellow or purplish; they are (like the related European Salix fragilis) brittle at the base, snapping evenly at the branch junction if bent sharply. The foliage buds are 2β4 millimetres (1β16β3β16 in) long, with a single, pointed reddish-brown bud scale. The leaves are alternate, long, thin, 5β15 centimeters (2β6 in) long and 0.5β2 centimeters (1β4β3β4 in) broad, usually somewhat falcate, dark, shiny green on both sides or with a lighter green underside, with a finely serrated margin, a short petiole and a pair of small stipules. It is dioecious, with small, greenish yellow to yellow flowers borne on catkins 2.5β7.5 centimeters (1β3 in) long in early spring at the same time as the new leaves appear. The fruit is a 5 millimeters (3β16 in) capsule which splits open when mature to release the numerous minute, down-covered seeds. The leaves turn a lemon yellow in the fall.