One of the world's largest willows when mature, black willow is so-named for its dark ebony bark. It most commonly grows in floodplains and riversides. Black willow provides some of the only economically important wood in the willow genus (Salix). The light but sturdy wood was once used for making artificial limbs, and is still used for fashioning boxes and making pulp. Birds eat the catkins, and other animals eat the bark and twigs. It is well-adapted to streamsides and is planted to reduce erosion. Many willows (Salix species) have bitter-tasting bark that contains derivatives of salicylic acid, the main compound in aspirin.tasting bark that contains derivatives of salicylic acid, the main compound in aspirin.