Hydrangea is a genus of 70–75 species of flowering plants native to southern and eastern Asia and the Americas. By far the greatest species diversity is in eastern Asia, notably China, Japan, and Korea. Most are shrubs 1 to 3 meters tall, but some are small trees, and others lianas reaching up to 30 m (98 ft) by climbing up trees. They can be either deciduous or evergreen, though the widely cultivated temperate species are all deciduous. Flowers are produced from early spring to late autumn; they grow in flower-heads (corymbs or panicles), most often at the ends of the stems. Typically the flower-heads contain two types of flowers: small non-showy flowers in the center or interior of the flower-head, and large, showy flowers with large colourful sepals (tepals). These showy flowers are often extended in a ring, or to the exterior of the small flowers. Plants in wild populations typically have few to none of the showy flowers, while cultivated hydrangeas have been bred and selected to have more of the larger type flowers. In most species the flowers are white, but in some species can be blue, red, pink, light purple, or dark purple. In these species the colour is affected by the presence of aluminium ions which are available or tied up depending upon the soil pH. Hydrangea roots and rhizomes are indicated for treatment of conditions of the urinary tract in the PDR for Herbal Medicine and may have diuretic properties They are moderately toxic if eaten, with all parts of the plant containing cyanogenic glycosides. In Japan and Korea, ama-cha or sugukcha respectively, meaning sweet tea, is herbal tea made from Hydrangea seratta, whose leaves contain a substance that develops a sweet taste (phyllodulcin). Credit: Wikipedia.