native to southern and eastern Asia (China, Korea, Japan, the Himalayas, and Indonesia) and North and South America.
grow in flowerheads (corymbs or panicles) at the ends of the stems. In many species,the flowerheads contain two types of flowers, small fertile flowers in the middle of the flowerhead, and large, sterile bract-like flowers in a ring around the edge of each flowerhead. Other species have all the flowers fertile and of the same size.
Common names include Bigleaf Hydrangea, French Hydrangea, Lacecap Hydrangea, Mophead Hydrangea, Penny Mac and Hortensia
In most species the flowers are white, but in some species (notably H. macrophylla), can be blue, red, pink, light purple, or dark purple. In these species the exact colour often mirrors the pH of the soil; acidic soils produce blue flowers, neutral soils produce very pale cream petals, and alkaline soils results in pink or purple. This is the caused by a color change of the flower pigments in the presence of aluminium ions which can be taken up into hyperaccumulating plants.
many selected to have only large sterile flowers in the flowerheads. Hydrangeas are moderately toxic if eaten.