40 Fun Facts About Hydrangeas

Hydrangea flowers that turn blue or pink depending on the soil act as a natural version of what?

A pH indicator in plant form: blooms come blue at a reading of about 5.5 or lower, pink at 6.5 or higher, and purple in between.

The name hydrangea comes from Greek words that liken the plant's tiny seed capsules to what?

Water vessel joins the Greek hydor and angeion, a grand name for seed capsules only a few millimetres across.

The big colourful 'petals' of a mophead hydrangea are not true petals at all but which flower part?

Sepals do the showing off on large sterile florets, while the hydrangea's fertile flowers are tiny and tucked out of sight.

Every part of a hydrangea is mildly poisonous if eaten because the plant holds compounds that release which toxin?

Cyanide is bound up in the plant's cyanogenic glycosides, yet hydrangeas are reportedly sometimes smoked as an intoxicant despite the danger.

In Japan, a herbal tea brewed from hydrangea leaves is poured over small statues each April to mark whose birthday?

The Buddha is bathed in the tea every April 8, a stand-in for the nectar that nine dragons poured over him at birth in legend.

Which US state named the oakleaf hydrangea, a native shrub of southeastern woodlands, as its official state wildflower?

Alabama chose it in 1999, honouring a shrub named for lobed leaves that turn red, bronze and purple in autumn.

Masses of summer hydrangeas earned Faial the nickname 'Blue Island' in which mid-Atlantic archipelago?

The Azores have adopted the shrub as an unofficial emblem and plant it along roadsides, although it was introduced and has turned invasive.

Soil treatments cannot change the flower colour of hydrangeas that bloom in which colour?

White hydrangeas make no pigment for soil chemistry to act on, so they stay white wherever they are planted.

In Japan, hydrangeas in full bloom are the classic emblem of which stretch of the year?

The rainy season falls in June, when apprentice geisha may wear seasonal hair ornaments of willow or, less often, blue hydrangea.

The hydrangea 'Runaway Bride Snow White' was named Plant of the Year for 2018 at which British flower show?

Chelsea gave its top new-plant prize to a hybrid bred in Japan, the homeland of the familiar bigleaf garden hydrangea.

Which metal must a bigleaf hydrangea absorb from acidic soil before its pink flowers can turn blue?

Aluminium reaches the roots only in acidic soil; alkaline soil locks the metal away, which is why the same shrub then flowers pink.

Gardeners who want pink rather than blue hydrangea flowers often dig in which material to make acidic soil alkaline?

Lime makes the ground more alkaline and so denies the roots the metal that blues the flowers, a trick that does nothing for oakleaf hydrangeas.

Which alternative name for the mophead hydrangea doubles as the Latin form of a French woman's given name?

Hortensia echoes the name Hortense, but no real Hortense has been pinned down, and the Larousse dictionary suspects the Latin word for garden instead.

A French naturalist tried to name the hydrangea after Nicole-Reine Lepaute, who helped predict the return of what?

Halley's Comet arrived in March 1759, one month before the date she and two colleagues had computed; an asteroid and a lunar crater now bear her name.

Naturalist Philipp Franz von Siebold named a hydrangea after his partner Taki while posted to which Japanese port city?

Nagasaki, where he served at the Dutch trading post of Dejima, now counts the hydrangea as its official city flower.

Gramado and Canela lie in a tourist district called the Region of the Hydrangeas in which South American country?

Brazil promotes the district to draw visitors to the hills of Rio Grande do Sul, where some locals still speak a German dialect.

HMS Hydrangea, launched in 1940, was one of the Royal Navy's flower-named convoy escorts built as which type of warship?

Corvette was a title the Royal Navy revived for these U-boat hunters, whose design was borrowed from a whale-catcher.

Wild bigleaf hydrangeas carry flat flowerheads of tiny central flowers ringed by showy ones, a form known as what?

Lacecap is the natural form; breeders later packed the whole head with showy florets to create the ball-shaped kinds that dominate gardens.

Climbing hydrangea scales tree trunks, rock faces and shady house walls by gripping with which structures?

Aerial rootlets sprout along its stems, though they grip less firmly than those of some wall-climbers, so gardeners often add ties.

Which nickname did smooth hydrangea earn because its stem bark peels away in several thin layers of different colours?

Sevenbark it is; the shrub grows wild across the eastern United States and spreads by creeping stems to form colonies.

Cherokee healers, and settlers after them, used the root of smooth hydrangea to treat which painful complaint?

Kidney stones and bladder stones were the target, and hydrangea root is still listed in herbal references as a possible diuretic.

The hydrangea sphinx, whose larvae feed on wild hydrangea in eastern North American wetlands, is which kind of insect?

A moth of the sphinx family Sphingidae, it also raises its young on buttonbush, another shrub of damp ground.

Hydrangea febrifuga, one of the fifty fundamental herbs of Chinese medicine, was long used against which disease?

Malaria is fought by its alkaloid febrifugine, and a synthetic cousin of that compound is now used in veterinary medicine.

Amacha, a Japanese drink brewed from fermented hydrangea leaves, has a name that translates into English as what?

Sweet tea earns the name from phyllodulcin, a compound in the leaves that is hundreds of times sweeter than table sugar.

Meigetsu-in, a Zen temple nicknamed the Temple of Hydrangeas for its June display, stands in which Japanese city?

Kamakura doubles up: its Hase-dera temple is also famous for a Hydrangea Path that blooms in June and July.

Ajisai, the Japanese word for hydrangea, is also the name of which mirror-covered object launched by Japan in 1986?

A satellite shaped like a hollow sphere, it carries 318 mirrors that flash sunlight back to Earth so surveyors can fix positions precisely.

The hydrangea family also includes which fragrant garden shrub, known to botanists as Philadelphus?

Mock orange is a cousin of the hydrangeas, named because its blossom looks like that of citrus trees and smells of orange flowers and jasmine.

Botanists place the hydrangea family in the order Cornales alongside which better-known group of flowering trees?

Dogwoods give the order its name through their genus Cornus, and the tupelo trees of American swamps belong to it too.

Most wild hydrangeas grow in East Asia, yet botanists first described the genus from plants in which American colony?

Virginia supplied the first described plants of a genus that runs to roughly a hundred species and ranges across Asia and the Americas.

Bigleaf hydrangeas pruned hard in spring often fail to bloom that summer because their flower buds sit on which stems?

Last year's growth carries the buds, which gardeners call blooming on old wood; reblooming varieties flower again later on new shoots.

The reds, purples and blues of bigleaf hydrangea flowers all come from one compound in which family of plant dyes?

Anthocyanins include the hydrangea's single colouring compound, also found in blueberries and blackcurrants, which shifts shade as it binds metal ions.

Which naturalist noted the oakleaf hydrangea in the 1770s while botanising from the Carolinas to the Florida panhandle?

William Bartram first documented it beside a brook in what is now south-central Georgia, yet the shrub was slow to catch on in gardens.

Carl Peter Thunberg first published Japan's bigleaf hydrangea in 1784 under a name placing it in which shrub genus?

Viburnum macrophyllum was his name for it, an easy slip given how alike the two shrubs' flowerheads can look at first glance.

An official Tasmanian list recommends bigleaf hydrangea for planting close to buildings because of which quality?

Low flammability earns it a place on the Tasmanian Fire Service's list of plants for the protection zone around a building.

Sugukcha, a herbal tea brewed from the leaves of mountain hydrangea, is a traditional drink of which country?

Korea also calls the drink isulcha, and the mountain hydrangea behind it grows wild there and in Japan.

Amacha, the hydrangea-leaf brew of Japanese temples, differs from green tea by containing none of which substance?

Caffeine is missing because the drink comes from a hydrangea, not the tea bush, and it is credited with antiallergic properties.

A Plant Heritage National Collection of hydrangeas, tended by volunteers in Darley Park, grows in which English city?

Derby City Council started the collection in 1984 at the request of Plant Heritage, a charity that works to keep garden plants from dying out.

Philipp Franz von Siebold, who brought Japanese hydrangeas to Europe, also introduced which shade-loving foliage plant?

Hosta species behind most modern garden kinds reached Europe through him, and he also shipped home the first Japanese giant salamander specimens seen on the continent.

Hydrangea serrata, the mountain hydrangea whose leaves are brewed into drinks, also goes by which lofty English name?

Tea of heaven is a tougher, more compact cousin of the bigleaf hydrangea, with smaller leaves and flowers and better tolerance of cold.

Hydrangea aspera, a large shrub of Himalayan forests, takes its Latin species name from which feature of its leaves?

Rough texture is the meaning of aspera, a nod to the downy undersides of leaves that can exceed 30 centimetres in some forms.