Salix alba, also known as the white willow, is a species of willow tree native to Europe and western and central Asia. The name “white willow” derives from the white tone to the undersides of the leaves. During harvesting, the strips of the willow bark are removed from the tree. Then, the inner bark is processed to remove the beneficial aqueous extract. Willow bark extract has been used for centuries for minor pain-relieving purposes and to soothe irritated skin.