hydrangea

Any of a group of flowering shrubs belonging to the saxifrage family, native to Japan. Cultivated varieties of H. macrophylla normally produce round heads of pink flowers, but these may be blue if there are certain chemicals in the soil, such as alum or iron. The name comes from the Greek for ‘water vessel’, after the cuplike seed capsules. (Genus Hydrangea, family Hydrangeaceae.)