Black Willow is the largest of the native willows of the United States, up to 90 feet or more in height. In Indiana it is found along stream and river banks and in low woods. The bark of the trunk is dark brown to black. Branches are greenish to dark brown. Leaves are long, about 2 to 5 inches, slender, and finely serrated. Flowers are long catkins. The wood was once used extensively for artificial limbs, because it is lightweight, doesn't splinter easily, and holds its shape well. It is still used for boxes and crates, furniture core stock, turned pieces and table tops. Ancient pharmacopoeia recognized the bark and leaves of willow as useful in the treatment of rheumatism. In 1829, the natural glucoside salicin was isolated from willow. Today it is the basic ingredient of aspirin, although salicyclic acid is synthesized rather than extracted in its natural state.