Hydrangea is a genus of more than 70 species of flowering plantsnativeto Asia and the Americas, with more than 600 known cultivars. Most are shrubs 1–3 m (3 ft 3 in – 9 ft 10 in) tall, but some are small trees, and others lianas reaching up to 30 m (100 ft) by climbing up trees. They can be either deciduous or evergreen. Hortensiaflowersare produced from early spring to late autumn; they grow in corymbs or panicles flowerheads most often at the ends of the stems. Typically the flowerheads contain two types of flowers: small non-showy fertile flowers in the center or interior of the flowerhead, and large, sterile showy flowers with large colorful sepals(tepals) extended in a ring to the exterior of the small flowers. Hydrangea flowers, when cut, dehydrate easily and wilt very quickly due to the large surface area of the petals. The petals of the hydrangea can also absorb water. Hydrangeas prefer shady areas with dappled sunlight and will grow happily near wet soil. The flowers of many hydrangea act as natural pH indicators, sporting blue flowers when the soil is acidic and pink ones when the soil is alkaline . Floral color change occurs due to the availability of aluminiumions depends upon the soil pH. An acidic soil (pH below 7), will have available aluminum ions and typically produce flowers that are blue to purple, whereas an alkaline soil (pH above 7) will tie up aluminium ions and result in pink or red flowers. Soil with a pH of 5.5 or lower will produce blue flowers, a pH of 6.5 or higher will produce pink hydrangeas, and soil in between 5.5 and 6.5 will have purple hydrangeas. White hydrangeas cannot be color-manipulated by soil pH because they do not produce pigment for color.