A plant pigment (flavonoid) that is found in certain fruits and vegetables. The major sources of rutin for medical use include buckwheat, Japanese pagoda tree, and Eucalyptus macrorhyncha. Other sources of rutin include the leaves of several species of eucalyptus, lime tree flowers, elder flowers, hawthorn leaves and flowers, rue, St. John’s Wort, Ginkgo biloba, apples, and other fruits and vegetables.