thumb|right| Close-up on a flowerhead showing the two flower types; [[Izu Ōshima, near Tokyo, Japan.]]

Hydrangea macrophylla is a species of flowering plant in the family Hydrangeaceae, native and endemic to Japan. It is currently treated as monotypic, with no subspecies or varieties. Natural wild plants, formerly sometimes distinguished as H. macrophylla var. normalis E.H.Wilson, but is currently treated as a separate species.

The species is naturalised in China, Korea, Siberia, New Zealand and the Americas, and has become an invasive species in the Azores and Madeira archipelagos.

Description

thumb|Hydrangea macrophylla by [[Abraham Jacobus Wendel, 1868]]

The term macrophylla means 'large- or long-leaved'. The opposite leaves can grow to in length. They are simple, membranous, orbicular to elliptic and acuminate. They are generally serrated.

The natural inflorescence of wild Hydrangea macrophylla is a corymb, with all flowers placed in a plane. Two distinct types of flowers are found; numerous central, small, fertile pentamerous ones, and a few peripheral, large, tetramerous ones; the latter are usually sterile, and whitish to pale blue or pinkish. An acidic soil (pH below 7) will usually produce a flower colour closer to blue, whereas an alkaline soil (pH above 7) will produce flowers of a pink, or even a red colour. This is caused by a colour change of the flower pigments in the presence of aluminium ions which can be taken up into hyperaccumulating plants. Scientists do not understand why this happens, whether it is due to predation or to attract pollinators.

Chemistry

Phyllodulcin, hydrangenol, and their 8-O-glucosides, and thunberginols A and F can be found in H. macrophylla. Thunberginol B, the dihydroisocoumarins thunberginol C, D and E, the dihydroisocoumarin glycosides thunberginol G 3'-O-glucoside and (−)-hydrangenol 4'-O-glucoside and four kaempferol and quercetin oligoglycosides can be found in Hydrangeae Dulcis Folium, the processed leaves of H. macrophylla var. thunbergii. The leaves also contain the stilbenoid hydrangeic acid.

The various colours, such as red, mauve, purple, violet and blue, in H. macrophylla are developed from one simple anthocyanin, delphinidin 3-glucoside (myrtillin), which forms complexes with metal ions called metalloanthocyanins.

Lunularic acid, lunularin, 3,4′-dihydroxystilbene and a glycoside of lunularic acid have been found in the roots of H. macrophylla.

Hydrangine is another name for the coumarin umbelliferone, and may be responsible for the possible toxicity of the plant.

Uses

thumb|right|Bud and leaves

Amacha is a Japanese beverage made from fermented leaves of Hydrangea macrophylla var. thunbergii.

Hydrangeae Dulcis Folium is a drug made from the fermented and dried leaves of H. macrophylla var. thunbergii with possible antiallergic and antimicrobial properties. It also has a hepatoprotective activity by suppression of D-galactosamine-induced liver injury in vitro and in vivo.

Hydrangea macrophylla is included in the Tasmanian Fire Service's list of low flammability plants, indicating that it is suitable for growing within a building protection zone.

Leaf extracts of Hydrangea macrophylla are being investigated as a possible source of new chemical compounds with antimalarial activity. Hydrangeic acid from the leaves is being investigated as a possible anti-diabetic drug as it significantly lowered blood glucose, triglyceride, and free fatty acid levels in laboratory animals.

Some popular hydrangea cultivars (those marked have gained the Royal Horticultural Society's Award of Garden Merit) include:

  • 'All Summer Beauty'; cold-hardy, floriferous mophead
  • 'Alpengluhen'; deep-red coloured mophead
  • 'Altona' ; compact plant with large rose-red florets
  • 'Ami Pasquier' ; floriferous, wine pink to blue mophead
  • 'Ayesha'; small, cupped, lilac-like flowers in clusters
  • 'Bailmer' (marketed as Endless Summer) a perpetual-blooming, pink to blue mophead
  • 'Beauté Vendômoise'; giant whitish-pink lacecap
  • 'Blaumeise' ; Swiss-bred "Teller" blue lacecap
  • 'Blue Bonnet'; hardy, blue mophead
  • 'Blue Wave'; robust light pink to light blue lacecap
  • 'Blushing Bride'; cold-hardy, ever-blooming white mophead
  • 'Cocktail'; bushy shrub with ovate, serrated sepals
  • 'Europa' ; compact, deep pink mophead
  • 'Forever Pink'; a pink mophead
  • 'Générale Vicomtesse de Vibraye' ; compact, cold-hardy, French-bred pink to blue mophead
  • 'Hamburg'; deep-coloured pink to blue mophead
  • 'Harlequin'; a picoteed pink to purple mophead
  • 'Lady in Red'; large lacecap flowers of rose-red
  • 'Lanarth White' ; white lacecap
  • 'Lilacina'; cold-hardy, disease-resistant pink to blue lacecap
  • 'Love You Kiss' ; red-margined white florets, lacecap
  • 'Madame Emile Mouillère' ; small shrub to , white flowers
  • 'Marechal Foch'; old-fashioned pink to blue mophead
  • 'Mariesii Grandiflora'; blue or pink and white lacecap
  • 'Mariesii Lilacina' ; mauve pink or blue lacecap
  • 'Mariesii Perfecta'; blue, or blue and pink, lacecap
  • 'Masja'; bushy and compact, dark pink to pink mophead
  • 'Möwe'; rose-red and cream lacecap
  • 'Nigra'; pink or blue mophead, black stems
  • 'Nikko Blue'; popular, cold-hardy pink to blue mophead
  • 'Pia'; dwarf pink to purplish-blue mophead
  • 'Penny Mac'; cold-hardy, pink to blue mophead
  • 'Rotschwantz’ ; deep red and white lacecap
  • 'Soeur Therese'; hardy, robust white mophead
  • 'Taube'; Swiss-bred "Teller", pink to blue lacecap
  • 'Tokyo Delight' ; mauve-pink and white lacecap
  • 'Twist-N-Shout'; ever-blooming, hardy pink to blue lacecap
  • 'Veitchii' ; blue and white lacecap
  • 'Westfalen' ; compact, crimson-purple mophead
  • 'Zorro’ ; bright blue lacecap

;Lacecaps

<gallery widths="150">

File:Hydrangeaceae - Hydrangea macrophylla 'Buntspecht', Villa Serra, Genova, Italy.jpg|'Buntspecht'

File:Gakuajisai6183.jpg|'Gakuajisai'

File:Hydrangeaceae - Hydrangea macrophylla - Geoffrey Chadbund.JPG|'Geoffrey Chadbund'

File:Hydrangea MacrophyllaTaube.JPG|'Taube'

File:Bigleaf Hydrangea Hydrangea macrophylla 'Tokyo Delight' Pink 3008px.jpg|'Tokyo Delight'

File:Hydrangeaceae - Hydrangea macrophylla - Zaunkoenig.JPG|'Zaunkoenig'

</gallery>

;Mopheads (also called hortensias)

<gallery widths="150">

File:Hydrangea macrophylla Ayesha 5zz.jpg|'Ayesha'

File:Hydrangeaceae - Hydrangea macrophylla - Beauté Vendomoise.JPG|'Beauté Vendomoise'

File:Hydrangeaceae - Hydrangea macrophylla - Harlequin.JPG|'Harlequin'

File:Hydrangeaceae - Hydrangea macrophylla - La Marne.JPG|'La Marne'

File:Hydrangeaceae - Hydrangea macrophylla - Mariesii.JPG|'Mariesii'

File:Hydrangeaceae - Hydrangea macrophylla - Merveille.JPG|'Merveille'

File:Nikko Petals 1.jpg|'Nikko Blue'

File:Hydrangea macrophylla - Pia.JPG|'Pia'

File:Hydrangeaceae - Hydrangea macrophylla - Red Ace.JPG|'Red Ace'

File:Hydrangeaceae - Hydrangea macrophylla - Satinette.JPG|'Satinette'

</gallery>

References

Yuan, Qi, H., Yang, S., Chu, Z., Zhang, G., & Liu, C. (2023). Role of delphinidin-3-glucoside in the sepal blue color change among Hydrangea macrophylla cultivars. Scientia Horticulturae, 313, 111902–. https://doi.org/10.1016/j.scienta.2023.111902

  • - Splendor In The Grass
  • Hydrangeas- Their Pruning and Care(Heronswood Nursery)
  • http://www.HydrangeasHydrangeas.com/mopheads.html - All About Hydrangeas: Information on Hydrangea macrophylla.
  • http://www.floridata.com/ref/h/hydran_m.cfm
  • http://www.clemson.edu/extension/hgic/plants/landscape/shrubs/hgic1067.html
  • Hydrangea Thoughts I - Informative but non-scholarly essay on Hydrangea (Culture, History and Etymology).