Chiba University Matsudo/Kashiwa Campus Plant Database

Details of genus: Hydrangea Gronov. ex L. [250]

genus_ja: アジサイ

genus_en:

# spp.: 86

pub_year: 1753

accepted: Accepted

Family: Hydrangeaceae

family_ja: アジサイ

Infra familial classification: Subfamily Hydrangeoideae: Tribe Hydrangeeae

distribution_en: China to Kuril Islands and Tropical Asia, Hawaiian Islands, N. Central & E. U.S.A. to Central & S. America

description_en: Genus of 80 or more species of deciduous and evergreen shrubs and climbers, rarely trees, found in woodland in E. Asia and North and South America. Grown mainly for their large, showy flowerheads, many hydrangeas also have ornamental, flaky, peeling bark when mature, and attractive foliage with good autumn colour. The leaves are broadly to narrowly ovate, or lance-shaped, toothed, and either opposite or in whorls of 3. The flat, domed, or conical, terminal flowerheads comprise corymbs or panicles of both tiny fertile flowers and larger sterile flowers with showy, petal-like sepals. Cultivars of H. macrophylla are divided into 2 groups: "Lacecaps" have flattened flowerheads with small fertile flowers in the centres, surrounded by larger sterile flowers; "Hortensias" (mophead hydrangeas) have spherical flowerheads of large sterile flowers. Some cultivars of H. serrata are also described as Lacecaps. Flower colour is affected by the relative availability of aluminium ions in the soil. Acid soils with a pH of less than 5.5 produce blue flowers; soils with a pH greater than this produce pink flowers. In more or less neutral soils, flower colour can be influenced by the addition of a blueing compound. White flowers are not affected by pH. Hydrangeas are useful for a range of garden sites: they are excellent as specimen plants or in group plantings, in a shrub border, or in containers. Use the climbers to clothe a shaded wall or fence. The flowerheads may be dried for use in arrangements. All parts of hydrangeas may cause mild stomach upset if ingested; contact with the foliage may aggravate skin allergies.

hardiness_en: Fully hardy to frost hardy.

cultivation_en:

propagation_en: Sow seed in containers in a cold frame in spring. Root soft-wood cuttings of deciduous hydrangeas in early summer, or hardwood cuttings in winter. Root semi-ripe cuttings of non-flowering shoots of evergreens with bottom heat in summer.

pests_en: Prone to grey mould (Botrytis), Hydrangea virus, powdery mildew, leafspot, honey fungus, aphids, red spider mites, scale insects, vine weevil, and capsid bugs.

description_ja:

comment:

comment_ja: アジサイ，ノリウツギ，アマチャ

type_species:

Phylogenetic definition:

Update Information: Created: 2007-12-06 12:51; Updated: 2023-07-19 10:06 by hkokubun@mac.com

family: