From the Manufacturer:
Hydrangea [Urinary]. Originally used by the Cherokee Indians for kidney support, hydrangea was introduced to early American settlers for similar purposes. A common shrub, hydrangea is a bitter and a solvent. Its solvent properties nutritionally support the urinary system. It contains natural minerals plus silicon, flavonoids, resins and saponins. In this formula, the dried, powdered root is used. Each capsule contains 325 mg hydrangea.