See text Hydrangea (/haɪˈdreɪndʒə/[3][4] or /haɪˈdreɪndʒiə/[5]), commonly named the hortensia, is a genus of more than 70 species of flowering plants native to Asia and the Americas.

[13] Hydrangea flowers are produced from early spring to late autumn; they grow in flowerheads (corymbs or panicles) most often at the ends of the stems.

Mophead flowers are large round flowerheads resembling pom-poms or, as the name implies, the head of a mop.

Hydrangea flowers, when cut, dehydrate easily and wilt very quickly due to the large surface area of the petals.

In other words, while the hue of the inflorescence is variable dependent upon cultural factors, the color saturation is genetically predetermined.

In these species, floral color change occurs due to the availability of aluminium ions, a variable which itself depends upon the soil pH.

[19] †Hydrangea knowltoni has been described from leaves and flowers recovered from the Miocene Langhian Latah Formation of the inland Pacific Northwest United states.

[20][21] Four fossil seeds of †Hydrangea polonica have been extracted from borehole samples of the Middle Miocene fresh water deposits in Nowy Sacz Basin, West Carpathians, Poland.

The following cultivars and species have gained the Royal Horticultural Society's Award of Garden Merit under the synonym Schizophragma:[24] Hydrangea root and rhizome are indicated for the treatment of conditions of the urinary tract in the Physicians' Desk Reference for Herbal Medicine and may have diuretic properties.

[32] Adding organic materials such as coffee grounds and citrus peel will increase acidity and turn hydrangea flowers blue.

[33] A popular pink hydrangea called Vanilla Strawberry has been named "Top Plant" by the American Nursery and Landscape Association.

A hybrid "Runaway Bride Snow White", from Japan, won Plant of the Year at the 2018 RHS Chelsea Flower Show.

[36] Hydrangeas were used by the Cherokee people of what is now the Southern U.S. A mild diuretic and cathartic, it was considered a valuable remedy for stone and gravel in the bladder.