Hydrangea

Lore & Background

The name Hydrangea is derived from Greek, meaning 'water vessel', in reference to the shape of its seed capsules. The earlier name Hortensia is a Latinised version of the French given name Hortense. Philibert Commerson attempted to call the flower Lepautia or Peautia in honor of astronomer Nicole-Reine Lepaute, but the common name became Hortensia. The Larousse remarks that the belief that Lepaute's name was Hortense is erroneous, and that the name probably came from hortus, meaning garden. Hydrangea flowers are produced from early spring to late autumn, growing in flowerheads (corymbs or panicles). Typically the flowerheads contain two types of flowers: small non-showy fertile flowers in the center, and large sterile showy flowers with colorful sepals. Cultivated hydrangeas have been bred to have more of the larger type flowers. Two main flower arrangements exist: mophead (large round flowerheads) and lacecap (flat flowerheads with a center core of small flowers surrounded by larger showy flowers). Hydrangea flower color can change based on soil pH. Soil with a pH of 5.5 or lower produces blue flowers, pH of 6.5 or higher produces pink flowers, and soil between 5.5 and 6.5 produces purple flowers. White hydrangeas cannot be color-manipulated by soil pH because they do not produce pigment for color. This color change is caused by the availability of aluminium ions, which depends on soil pH.

Reader's Guide

They are widely cultivated for their large, showy flowerheads, which can change color based on soil acidity—a natural pH indicator. The genus has a rich fossil record, with species such as †Hydrangea alaskana from Paleogene strata in Alaska and †Hydrangea knowltoni from Miocene deposits in the Pacific Northwest. In traditional medicine, hydrangea root and rhizome are indicated for urinary tract conditions and may have diuretic properties, though all parts contain cyanogenic glycosides and are moderately toxic if eaten. In culture, Hydrangea serrata is used in Japan to make ama-cha (sweet tea) for the Buddha bathing ceremony, and in Korea for sugukcha herbal tea.

Did You Know?

• Hydrangea flower color acts as a natural pH indicator: blue in acidic soil, pink in alkaline soil.
• The name Hydrangea is derived from Greek for 'water vessel', referring to the shape of its seed capsules.
• In Japan, Hydrangea serrata is used to make ama-cha, a sweet tea poured over a statue of Buddha on his birthday.