Nature’s Way White Willow Bark Description: Maximum Potency Contains 15% Salicin White Willow Bark (Salix alba) was the basis for the synthesis of aspirin. It contains salicin and related compounds.Did you know? Nature’s Way White Willow Bark is harvested from wild trees by a careful stripping process that does not hinder the growth of the tree. Disclaimer These statements have not been evaluated by the FDA. These products are not intended to diagnose, treat, cure, or prevent any disease.