Accepted name: Hydrangea macrophylla
Deciduous shrub. New growth more or less hairless. Leaves broadly ovate, mostly shiny above, to 20 cm long, margins with large teeth. Flowers of wild species in more or less flattened clusters but those of garden variants generally more or less spherical (moptops or hortensias), although garden variants of the flattened cluster type also available (lacecaps); summer. Sepals 4 or 5, small and inconspicuous except in sterile flowers when there may be 3-5, large, showy and petal-like, arranged around the flower or, when all the flowers are sterile, in a ball. Petals 4 or 5, white, blue or pink to purplish, often deepening in colour with age. Ovary inferior, becoming half-inferior in fruit. Fruit capsule woody, with 3 diverging styles.
[H. hortensis Siebold, H. opuloides (Lam.) Anon.]
The exact origin of the common garden form with a ball of sterile flowers is not known with certainty. It has been suggested that it is a natural variant derived from H. macrophylla var. normalis E.H.Wilson which has a lacecap flower; it has also been suggested that it is the result of horticultural breeding and selection.
Garden cultivars of this species are of 2 kinds: the Mopheads (Hortensias) and Lacecaps. Mopheads have all flowers sterile, forming a more or less spherical cluster. Lacecaps have flowers that form a more or less flat-topped cluster, the large sterile flowers being arranged around the outside and the small fertile flowers clustered in the centre.The distinction between mopheads and lacecaps is not always clear: some cultivars are variable and may intergrade, e.g. 'Libelle'.There are over 500 cultivars worldwide, derived largely from H. macrophylla and H. serrata; the list presented here is a selection of cultivars in Australia and the number would double if it included cultivars in specialist collections.
There is an uncanny similarity between these flower forms and those of some viburnums although in Hydrangea the sepals are free, not fused as in Viburnum, and the leaves of the 2 genera are quite different.
Flower colour is affected primarily by pH (which influences the availability of aluminium, the main determinant of flower colour). In alkaline soils without aluminium the flower colour is pink, in strongly acid soils flowers are blue. The addition of aluminium sulphate can change flower colour from pink to blue.
MOPHEADS (HORTENSIAS) Flowers in this group are mostly large and sterile in a more or less spherical cluster. Mopheads have been raised mostly by Dutch, French, German and Swiss breeders beginning in the 19th century, but many have been introduced in the 20th century. Flower heads variable in size and flower density. Sterile flowers are single or double and the petal-like sepals have margins that are rounded, wavy, or toothed. Shrubs may vary in size according to growing conditions. Flower size, colour and even sepal structure may vary with soil conditions and pruning regimes. Flower colour ranges through white and cream to pinks, crimson, purple, violet and blue. Distinguishing cultivars is often difficult as differences are often small; names have sometimes been guessed at or invented anew. The following list is an attempt to come to terms with the existing names but a complete revision of all the available cultivars is needed.
LACECAPS Flower heads more or less flat, the centre of small fertile flowers surrounded by an outer ring of large, sterile flowers. These are best known under their English names.
A range of new releases introduced from Japan includes the compact bicolors: 'Mariko', blue and white; 'Nobuko', purple and white; 'Taiko', violet blue and white; 'Machiko', pink and white; 'Sumiko', white and pink; and 'Reiko', a pink and white lacecap.
Source: (2002). Hydrangeaceae. In: . Horticultural Flora of South-eastern Australia. Volume 3. Flowering plants. Dicotyledons. Part 2. The identification of garden and cultivated plants. University of New South Wales Press.
Cluster compressed hemispherically. Flowers red, each about 4.5 cm wide, sepals often toothed and paler pink below. Raised by Henri Cayeux in 1934, sometimes wrongly attributed to Draps-Dom, Belgium, 1950.
Flower cluster large. Flowers creamy white. Raised ÃÂâÂ°. MouillÃÂÂ¨re, 1909.
Late-flowering, with shortened leaves. Flower cluster rose-coloured or deep blue in acid soils. Sepals with serrated edges. Purple and crimson in autumn. Originated h. Schadendorff in 1931.
Small bush to 1 m tall. Flowers small, pink or blue, becoming mauve at maturity, irregular, double, with sharply toothed sepals. Raised by m. Haworth- Booth from a seedling of 'Europa', 1938.
Leaves roundish, glossy and sharply toothed. A probable selection bred from a seedling of 'MarÃÂÂ©chal Foch' and grown for the red flowers which become rich purple in acid soils. Raised ÃÂâÂ°. MouillÃÂÂ¨re, France, 1930.
Flowers delicate pink, mauve or blue, abundant, lilac-like, with the edges inrolled to look like small spoons; slightly fragrant. Sports to produce 'Joseph Banks'. Derived from 'Forget-me-Not', a distinct cultivar with all fertile flowers. ['Blue Popcorn' is probably a synonym]
Flower heads round, pink or blue. Raised by c. Marchant of Farnham, Dorset, uk, as a branch sport of 'gÃÂÂ©nÃÂÂ©rale Vicomtesse de Vibraye', grown for the long flowering period and prolific flowers. Sometimes referred to by the common name, Paddock Hydrangea.
This cultivar name is the German name for Lake Constance. Shrub to about 1 m tall. Flowers prolific, dark pink, easily converting to pure blue in acid soil. Sepals 5, with entire edges. Raised by Brugger, Germany, but the date unknown; after 1950.
Flowers abundant. Sepals toothless, similar, pale pink, mauve or blue. Selected by Mrs Violet Clive of the Brympton d'Emercy garden, c. 1946, possibly as a branch sport of 'BeautÃÂÂ© VendÃÂÂ´moise'.
Flower clusters bright pink or blue, long-lasting. A common old plant. Origin unknown.
Flowers crimson, much darker in acid soils. Originated j. Wintergalen, 1937.
Shrub less than 1 m tall, sometimes with fasciated stems. Flower clusters conical in outline. Flowers double-frilled, pale pink, or mauve in acid soil, the truss often uneven, with some individual flowers large. Old Japanese cultivar.
Large shrub with clear yellow foliage in autumn. Flower clusters large, pale blue, developing an unusual autumn slate colour.
Flowers deep pink. Origin unknown.
Flower clusters flattened hemispherically. Flowers pure deep blue, about 5.5 cm wide. Name derived from the German word Enzian - gentian, recalling the vibrant blues of this genus. Originated August Steiniger, 1950.
Flower clusters dark blue in acid soil. Sepals toothed.
Low bush. Flower clusters small, best in acid soil. Possibly a cultivar of Australian origin and probably also available as 'Blue Montgomery'.
Considered as possibly a lacecap variant of 'Ami Pasquier' with rounded, entire sepals. Named by l.r. Russel after the author of a book on flowering cherries. ['Mont Jean' is probably a synonym]
Shrub to 2 m or so tall, with broad leaves. Flower clusters large, hence the name, pink or blue. Sepals wrinkled, mostly in 4s, green in neutral soil. Dries well. Raised by f. Matthes, 1923. ['Goliath Emerald']
Flowers red. Origin unknown.
Flowers extremely large, deep pink to purple or blue sepals. Good autumn colour, probably derived from h. serrata.
S pink topper' Flowers salmon pink. Origin unknown.
Flowers red, purple in acid soil, the sepals with toothed to lobed edges. Raised f. Matthes in 1929 and named after a 19th century German poet.
Large shrub. Flower clusters large and spherical, to 25 cm wide, white with suffusion of pink and mauve. Sterile flowers with 4 entire sepals, becoming flecked with pink. Fertile flowers in the centre of the cluster are very large. A sport of 'Ayesha'. ['Sir Joseph Banks']
Flower clusters rosy pink, cobalt blue in acid soil, greenish blue in autumn. Sepals large with serrated edges. Raised h.j. Jones in 1927 and imported from Hillers Nsy, uk, by Teddy Woolrich. Different plants may be available under this name.
Large shrub to 2 m or more tall. Flower clusters plentiful, large. Sepals rounded and often with pink wavy edge. Raised f.k. Kluis, 1932, as a cross of 'MarÃÂÂ©chal Foch' and 'La Marne'. [Available, incorrectly, as 'Superba']
Flower clusters large, pale pink or blue. Sepals with large teeth, centre of flower tinged dark blue. Late-flowering. Raised by ÃÂâÂ°. MouillÃÂÂ¨re in 1920.
Tall shrub. Flowers white. Raised h. Cayeux, France, 1919.
Low-growing shrub. Flower heads with extremely large lateral sterile florets to 6 cm or so wide and of 4-5 sepals. Fertile flowers mostly blue. Long-flowering. Raised f. Meier, 1964.
Named by Warners' Nsy, Burwood, Vic, after the lady who supplied the nsy with cuttings.
Fertile flowers pale blue or pink, surrounded by about 8 blushed, marginal, sterile flowers, each with 4 similar, slightly wavy, toothless sepals. Raised by v. Lemoine, c. 1902, from naturally pollinated seed taken from 'Mariesii'; selected in 1902. Invalidly named 'White Wave' by Haworth-Booth in the 1950s to avoid confusion with other 'Mariesii' derivatives. ['White Wave'] Plants sold as 'White Wave' or 'Lanarth White' may be 'BeautÃÂÂ© VendÃÂÂ´moise', which was raised by ÃÂâÂ°. MouillÃÂÂ¨re from 'Mariesii Grandiflora' and 'Rosea'.
Flower clusters small, sepals with serrated edges, from pink to lilac or pure blue. Raised by ÃÂâÂ°. Lemoine in 1904 as a chance seedling of 'Mariesii' with h. serrata a possible parent. Invalidly named 'Lilacina' by Haworth-Booth in the 1950s to avoid confusion with other 'Mariesii' derivatives. ['Lilacina']
Sturdy-branched shrub. Flower clusters symmetrical, midway between a moptop and lacecap, the sterile ray flower sepals with wavy edges. Needs strongly acidic conditions to achieve a strong blue. Raised by ÃÂâÂ°. Lemoine from naturally pollinated seed of 'Mariesii' and released in 1904. Invalidly renamed 'Blue Wave' by Haworth-Booth in 1950 to avoid confusion with the parent plant. ['Blue Wave']
Flowers crimson. Heads small. Raised by h. Cayeux in 1928.
Mostly about 1m tall. Flower clusters at least a few, violet, broad and open, often a striking blue. Sepals sharply toothed. Raised August Steiniger, 1946.
S supreme' Compact semi-dwarf shrub. Sepals large and toothed. Possibly originating in the usa.
Shrub to 1 m or so tall. Flowers ultramarine in acid soil. Raised d. Draps, 1935.
Tall, wide-spreading shrub. Flower clusters large, pink to blue with numerous crowded florets. Sepals 4, entire, blue-green, blotched with red in autumn. Raised ÃÂâÂ°. Lemoine, 1909. ['Messalina']
Vigorous grower. Flowers in large heads, pink or deep blue.
Dwarf plant to 30 cm or so tall, sometimes reverting to a larger form, especially when fed well. Flower clusters small, pink, compressed, the centre whitish. Sepals of different sizes and with tiny teeth, pointed when young.Origin unknown. ['Pia Mina' a New Zealand-raised dwarf cultivar with foliage colouring well is possibly the same as above]
Flowers pink. Origin unknown.
Flowers red, early. Origin unknown.
Derived from 'Mariesii' with leaves in 4 colour variegations: strong yellow, cream, pale and dark green. Origin unknown.
Flowers deep pinkish red, late. Raised e. Draps, 1938.
Strong-growing shrub with elliptic leaves having an extended point. Flower clusters white, firm. Raised Moll, Zurich, 1934.
Smaller grower. Florets large, sepals plain, deep red or strong purple.
Sterile florets of 5 sepals, white, tinged with mauve, while the fertile flowers are violet or dark blue. Derived from typical h. macrophylla.
Mostly medium shrub. Late-flowering. Flower heads round, the florets of 3-4 sepals. Raised August Steineger, pre-1983.
Shrub with wrinkled leaves, growing to about 1 m tall. Flower clusters fairly open. Sepals entire, irregular. Origin unknown.
Flowers red, early. Sepals rounded. Unfolding flowers appear cup-like. Origin unknown.
Flowers pale pink or blue, with strongly serrated sepals. Origin unknown.
As for 'Quadricolor', derived from 'Mariesii', but leaves in 3 colour variegations: pale yellow, dark green and pale green. Shrub to 2 m or so tall. Flowers prolific over a long period. Raised by Messrs Rovere of Pallanza, Italy, before 1860, probably as a branched sport of 'Mariesii'.
Large shrub. Flowers exceptionally deep blue. Origin unknown.
Leaves variegated. There are possibly 2 different kinds listed here, 1 derived from the lacecap original, h. macrophylla, the other from a 'Mariesii'. ['Tricolor']
Leaves variegated. There are possibly 2 different kinds listed here, one derived from h. macrophylla var. normalis, the other from a 'Mariesii' lacecap and possibly better referred to h. macrophylla 'Maculata'. ['Tricolor']
Shrub to 2 m or so tall. Flower clusters early, pure white, the sterile florets with pointed sepals in 3s, rarely with a reduced 4th sepal, becoming pink or brownish in autumn. An old Japanese cultivar imported to the uk by c. Maries, c. 1881.