Hydrangea (/haɪˈdreɪndʒiə/; common names hydrangea or
hortensia) is a genus of 70–75 species of flowering plants native to
southern and eastern Asia (China, Japan, Korea, the Himalayas, and
Indonesia) and the Americas. By far the greatest species diversity is
in eastern Asia, notably China, Japan, and Korea. Most are shrubs 1 to
3 meters tall, but some are small trees, and others lianas reaching up
to 30 m (98 ft) by climbing up trees. They can be either
deciduous or evergreen, though the widely cultivated temperate species
are all deciduous.
Having been introduced to the Azores, H. macrophylla is now very
common, particularly on Faial, which is known as the "blue island" due
to the vast number of hydrangeas present on the island.
1 Life cycle
2 Colours and soil acidity
3 Partial list of species
4 Cultivation and uses
9 External links
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. Typically the flowerheads contain two types of flowers:
small non-showy flowers in the center or interior of the flowerhead,
and large, showy flowers with large colorful sepals (tepals). These
showy flowers are often extended in a ring, or to the exterior of the
small flowers. Plants in wild populations typically have few to none
of the showy flowers, while cultivated hydrangeas have been bred and
selected to have more of the larger type flowers.
There are two flower arrangements in hydrangeas with corymb style
inflorescences, which includes the commonly grown "bigleaf
Hydrangea macrophylla. Mophead flowers are large round
flowerheads resembling pom-poms or, as the name implies, the head of a
mop. In contrast, lacecap flowers bear round, flat flowerheads with a
center core of subdued, small flowers surrounded by outer rings of
larger flowers having showy sepals or tepals. The flowers of some
rhododendrons and viburnums can appear, at first glance, similar to
those of some hydrangeas.
Colours and soil acidity
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 color is affected by the presence of aluminium ions
which are available or tied up depending upon the soil pH. For
H. macrophylla and H. serrata cultivars, the flower color can be
determined by the relative acidity of the soil: an acidic soil (pH
below 7), will have available aluminum ions and typically produce
flowers that are blue to purple, whereas an alkaline soil (pH above
7) will tie up aluminum ions and result in pink or red flowers. This
is caused by a color change of the flower pigments in the presence of
aluminium ions which can be taken up into hyperaccumulating plants.
Lowering the pH of potting soils or mixes usually does not change the
flower color to blue, because these soils have no aluminum ions. The
ability to blue or pink a hydrangea is also influenced by the
cultivar. Some plants are selected for their ability to be blued,
while others are bred and selected to be red, pink or white. The
flower color of most other
Hydrangea species is not affected by
aluminum and cannot be changed or shifted. Hydrangeas also have a
nickname called 'Change Rose'.
Partial list of species
Hydrangea alaskana a fossil species recovered from paleogene strata
in Jaw Mountain Alaska.
Hydrangea anomala (climbing hydrangea). Himalaya, southwest Mainland
Hydrangea arborescens (smooth hydrangea). Eastern North America.
Hydrangea aspera. Mainland China, Himalaya.
Hydrangea bretschneideri. Mainland China.
Hydrangea candida. Mainland China.
Hydrangea caudatifolia. Mainland China.
Hydrangea chinensis. Mainland China.
Hydrangea chungii. Mainland China.
Hydrangea cinerea (ashy hydrangea). Eastern United States.
Hydrangea coacta. Mainland China.
Hydrangea coenobialis. Mainland China.
Hydrangea davidii. Mainland China.
Hydrangea dumicola. Mainland China.
Hydrangea gracilis. Mainland China.
Hydrangea heteromalla. Himalaya, west and north Mainland China.
Hydrangea hirta. Japan.
Hydrangea hypoglauca. Mainland China.
Hydrangea integrifolia. Mainland China.
Hydrangea involucrata. Japan, Taiwan.
Hydrangea kawakamii. Taiwan.
Hydrangea kwangsiensis. Mainland China.
Hydrangea kwangtungensis. Mainland China.
Hydrangea lingii. Mainland China.
Hydrangea linkweiensis. Mainland China.
Hydrangea longifolia. Mainland China.
Hydrangea longipes. Western China.
Hydrangea macrocarpa. Mainland China.
Hydrangea macrophylla (bigleaf hydrangea). Southeast Japan, southern
Hydrangea mangshanensis. Mainland China.
Hydrangea paniculata (panicled hydrangea). Eastern Mainland China,
Japan, Korea, Sakhalin.
Hydrangea petiolaris (climbing hydrangea). Japan, Korea, Sakhalin.
Hydrangea quercifolia (oakleaf hydrangea). Southeast United States.
Hydrangea radiata (silverleaf hydrangea). Southeast United States.
Hydrangea robusta. Mainland China, Himalaya.
Hydrangea sargentiana. Western Mainland China.
Hydrangea scandens. Southern
Japan south to the Philippines.
Hydrangea serrata. Japan, Korea.
Hydrangea serratifolia. Chile, western Argentina.
Hydrangea stenophylla. Mainland China.
Hydrangea strigosa. Mainland China.
Hydrangea stylosa. Mainland China.
Hydrangea sungpanensis. Mainland China.
Hydrangea xanthoneura. Mainland China.
Hydrangea zhewanensis. Mainland China.
Cultivation and uses
Hydrangeas are popular ornamental plants, grown for their large
Hydrangea macrophylla being by far the most widely
grown with over 600 named cultivars, many selected to have only large
sterile flowers in the flowerheads.
Hydrangea macrophylla, also known
as Bigleaf Hydrangea, can be broken up into two main categories;
Hydrangea & Lacecap Hydrangea. Some are best pruned on
an annual basis when the new leaf buds begin to appear. If not pruned
regularly, the bush will become very 'leggy', growing upwards until
the weight of the stems is greater than their strength, at which point
the stems will sag down to the ground and possibly break. Other
species only flower on 'old wood'. Thus new wood resulting from
pruning will not produce flowers until the following season.
Hydrangea root and rhizome are indicated for treatment of conditions
of the urinary tract in the PDR for Herbal Medicine and may have
diuretic properties. Hydrangeas are moderately toxic if eaten, with
all parts of the plant containing cyanogenic glycosides. Hydrangea
paniculata is reportedly sometimes smoked as an intoxicant, despite
the danger of illness and/or death due to the cyanide.
In Japan, ama-cha,甘茶 meaning sweet tea, is another herbal tea made
Hydrangea serrata, whose leaves contain a substance that develops
a sweet taste (phyllodulcin). For the fullest taste, fresh leaves are
crumpled, steamed, and dried, yielding dark brown tea leaves. Ama-cha
is mainly used for kan-butsu-e (the
Buddha bathing ceremony) on April
8 every year—the day thought to be Buddha's birthday in Japan.
During the ceremony, Ama-cha is poured over a statue of
served to people in attendance. A legend has it that on the day Buddha
was born, nine dragons poured
Amrita over him; ama-cha is substituted
Amrita in Japan.
In Korean tea,
Hydrangea serrata (hangul:산수국 hanja:山水菊) is
used for an herbal tea called sugukcha (수국차) or ilsulcha
The pink hydrangea has risen in popularity all over the world, but
especially in Asia. Pink hydrangeas have many different meanings, but
generally mean, "You are the beat of my heart," as described by the
celebrated Asian florist Tan Jun Yong, where he was quoted saying,
"The light delicate blush of the petals reminds me of a beating heart,
while the size could only match the heart of the sender!"
A popular pink hydrangea called Vanilla Strawberry has been named "Top
Plant" by the American Nursery and Landscape Association.
Hydrangea flowers close up.
Hydrangea macrophylla, flowers.
Hydrangea macrophylla, flowers
Hydrangea sp painted by the botanical artist Redouté.
Hydrangea macrophylla, leaves
Hydrangea v. Annabelle
Hydrangea v. Annabelle
Hydrangea aspera ssp. sargentiana
Hydrangea flowers from Kerala, India
H. macrophylla, Watermouth Castle, north Devon, England.
Hydrangeas in front of the Office de Tourisme Building in Chartres,
Hydrangea flowers at the "Cerro El Avila" National Park, Venezuela.
Hydrangea flowers, Srinagar, Kashmir, India.
Hydrangea flowers blooming at the Kanonji temple (Japan).
Hydrangea flowers in Petrópolis, Brazil.
Hydrangeas near the Black Lake of Gramado, southern Brazil.
Purple hydrangea flowers
Hydrangea arborescens leaf
Main article: List of hydrangea diseases
^ Sunset Western Garden Book, 1995:606–607
^ "The United States National Arboretum:
^ University of Georgia: Growing Bigleaf Hydrangea
Hydrangea Questions and Answers
^ "Hydrangea". Encyclopædia Britannica 1911. Retrieved
^ Hollick, Arthur (1925). "A New Fossil Species of Hydrangea".
Bulletin of the Torrey Botanical Club. 52 (1): 21–22.
^ "The Complete Guide to All
plantaddicts.com. Retrieved 2017-11-20.
^ PDR for Herbal Medicine 3rd Edition Page 453
^ ASPCA Animal Poison Control Center
^ High danger hydrangea? The Guardian French police hunt gang
peddling 'cheaper weed'
^ Roll Magazine
This article incorporates text from a publication now in
the public domain: Chisholm, Hugh, ed. (1911). "Hydrangea".
Encyclopædia Britannica. 13 (11th ed.). Cambridge University Press.
Wikimedia Commons has media related to Hydrangea.
Wikispecies has information related to Hydrangea
Flora of Nepal:
Hydrangea species list
Hydrangea – selecting shrubs
Hydrangea species and hybrids
Red Listing of Threatened Hydrangeas