Having been introduced to the Azores Islands of Portugal, they are now very common there, particularly on Faial, which is known as the "blue island" due to the vast number of hydrangeas present on the island, Terceira, named the "lilac island" for hydrangeas of that colour, on Flores Island ("Island of Flowers") and São Miguel, named the "green island" for its floral biodiversity.
Species in the related genus Schizophragma, also in Hydrangeaceae, are also often known as hydrangeas. Schizophragma hydrangeoides and Hydrangea petiolaris are both commonly known as climbing hydrangeas.
There are two flower arrangements in hydrangeas. Mophead flowers are large round flowerheads resembling pom-poms or, as the name implies, the head of a mop. In contrast, lacecap flowers bear round, flat flowerheads with a center core of subdued, fertile flowers surrounded by outer rings of showy, sterile flowers. The flowers of some rhododendrons can appear similar to those of some hydrangeas, but Rhododendron (including azalea) is in a different order.
Read more about Hydrangea: Life Cycle, Colors and Soil Acidity, Partial List of Species, Cultivation and Uses, Gallery