Hydrangea (/ha?'dre?nd?i?/;common labels hydrangea or hortensia) is a genus of 70-75 varieties of flowering vegetation native to southern and eastern Asia (China, Japan, Korea, the Himalayas, and Indonesia) and the Americas. Probably the greatest species diversity is eastern Asia, notably China, Japan, and Korea. Most are shrubs 1 to 3 meters tall, however, many are small trees and shrubs, and others lianas reaching up to 30 m (98 foot) by climbing up trees. They can be either deciduous or evergreen, though the cultivated temperate species are deciduous broadly.Having been introduced to the Azores, H. macrophylla is very common now, particularly on Faial, which is known as the "blue island" because of the multitude of hydrangeas present on the island.Life cycleHydrangea flowers are produced from planting season to late fall months; they develop in flowerheads (corymbs or panicles) frequently at the ends of the stems.
Usually the flowerheads contain two types of plants: small non-showy plants in the center or interior of the flowerhead, and large, showy bouquets with large colourful sepals (tepals). These showy flowers are extended in a band often, or to the exterior of the tiny flowers. Vegetation in outrageous populations have few to none of them of the showy blooms typically, while cultivated hydrangeas have been bred and picked to have more of the bigger type blooms.There are two flower arrangements in hydrangeas with Corymb style inflorescens, which include the commonly grown "bigleaf hydrangea"--Hydrangea macrophylla. Mophead bouquets are large round flowerheads resembling pom-poms or, as the name implies, the mind of any mop. On the other hand, lacecap flowers bear round, flat flowerheads with a center core of subdued, small plants surrounded by outer jewelry of greater plants having showy tepals or sepals.
The blooms of some rhododendrons and viburnums can look, at first glance, similar to those of some hydrangeas.Colors and ground acidityIn most varieties the plants are white, but in some kinds (notably H. macrophylla), can be blue, red, red, light crimson, or dark crimson. In these species the colour is afflicted by the existence of light weight aluminum ions which can be found or tangled up depending after the garden soil pH. For H. macrophylla and H. serrata cultivars, the flower color can be dependant on the relative acidity of the soil: 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 aluminum ions and bring about pink or red flowers.
This is caused by a color change of the rose pigments in the existence of aluminium ions which is often adopted into hyperaccumulating plant life.[6] Bringing down the pH of potting soils or mixes usually does not change the bloom color to blue, because these soils haven't any aluminum ions. The capability to blue or green a hydrangea is also affected by the cultivar. Some plants are selected because of their ability to be blued, while others are bred and selected to be red, pink or white. The flower color of all other Hydrangea species is not influenced by aluminum and cannot be changed or shifted. Hydrangeas also have a nickname called 'Change Rose'.