White Willow

White willow (Salix alba) is a medium to large deciduous tree that grows up to 10-30 m tall. It is native to Europe and western and Central Asia, and its name comes from the white tone of the undersides of the leaves. The bark is grey-brown and deeply fissured in older trees.

Willows have watery bark sap rich in salicin. Salicin is an alcoholic β-glucoside that is produced in willow bark and named after the genus Salix. It hydrolyses into β-D-glucose and salicyl alcohol, and it has the formula C₁₃H₁₈O₇. The bark of white willow does not contain much salicin compared with other willows. It also contains bitter-tasting tannins.

In 1763 Edward Stone, of Chipping Norton, Oxfordshire, sent a letter to the Royal Society describing his experiments with powdered white willow bark. He had noticed that the bark tasted bitter, like Peruvian bark, which was used to treat fevers. Salicin was isolated in crystalline form in 1828 by Henri Leroux, a French pharmacist, and Raffaele Piria, an Italian chemist. By 1838 Piria had found a method of obtaining a more potent acid form of willow extract, which he named salicylic acid. In 1897 Felix Hoffmann, or perhaps Arthur Eichengrün, was the first to produce acetylsalicylic acid in a pure, stable form.

The wood is tough, strong and light in weight, and it is used to make cricket bats. The stems from coppiced and pollarded plants are used for basket-making. The bark tannin was used in the past for tanning leather. The wood has minimal resistance to decay, and charcoal made from it was important for gunpowder manufacture.

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Related: Alder · Alpha Humulene · Amaranth · Amberever · Amburana Bark · Apple Tree