Hydrangea macrophylla (Thunb.) Ser., Hydrangeaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Hortensia opuloides Lam.; Hydrangea chungii Rehder; Hydrangea hortensia Siebold; Hydrangea opuloides (Lam.) K. Koch; Viburnum macrophyllum Thunb.

Common name(s): [more details]

English: French hydrangia, hortensia, hydrangea, lacecap hydrangea, tea-of-heaven

French: hortensia à grandes feuilles

Hawaiian: pōpōhau

Japanese: ajisai, gaku-ajisai

Habit:  herb

Description:  "Deciduous, densely-branched, rounded shrub to 1.5-(3) m high; twigs glabrous and flexible, becoming mottled and brittle. Leaves towards ends of branches on younger wood; petiole short; lamina elliptic to ovate or obovate, (5)-10-20 x (3)-5-15 cm, acuminate, cuneate, coarsely serrate; both surfaces glabrous and greasy, the upper lustrous, the lower dull with a conspicuous network of veins. Corymb broad, flat-topped or convex, much-branched, hairy, up to 20 cm in diameter, usually largely composed of sterile flowers, sometimes with an outer ring of sterile flowers and central flowers fertile. Sepals of sterile flowers petaloid, spreading, broad-elliptic to obovate, 1-2 cm long, pink, blue, white, or greenish. Corolla c. 3 mm in diameter; petals minute and incurved, pink or blue. Stamens 10. Ovary enclosed in calyx tube at anthesis, later projecting. Capsule 5 mm long"  (Webb et al., 1988; p. 757).

Habitat/ecology:  In New Zealand, "regions of moderate to high rainfall, mostly wasteland, scrub, and forest margins, also coastal habitats.  Hydrangea is frequent as a long-persistent relict or as deliberate plantings on forest margins in wetter parts of New Zealand; some forms also set seed and have established as small wild populations"  (Webb et al., 1988; p. 757).

Propagation:  Seed

Native range:  Japan; also cultivated and naturalized (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive cultivated	Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive cultivated	Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (pp. 486, 532, 554) "Presente en jardines del pueblo de San Juan Bautista, se encuentra también fuera de ellos (Plazoleta del Yunque). Esta especie debe ser vigilada muy de cerca y seria prudente suprimir los ejemplares que crecen fuera de los jardines".
Ecuador (Galápagos Islands) Isabela Group	Isabela Island	introduced cultivated	Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands) San Cristóbal Group	San Cristóbal Island	introduced cultivated	Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands) Santa Cruz Group	Santa Cruz Island	introduced cultivated	Charles Darwin Foundation (2008)
Federated States of Micronesia Kosrae Island	Kosrae Island	introduced cultivated	Lorence, David H./Flynn, Timothy (2010) (p. 18)
French Polynesia Marquesas Islands	Nuku Hiva (Nukahiva) Island	introduced cultivated	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) Cultivée
French Polynesia Society Islands	Tahiti Island	introduced cultivated	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) Cultivée
French Polynesia Austral (Tubuai) Islands	Raivavae (Raevavae) Island	introduced cultivated	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) Cultivée
French Polynesia Austral (Tubuai) Islands	Rurutu Island	introduced cultivated	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) Cultivée
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island		Bishop Museum (U.S.A. Hawaii. Honolulu.) (1990) (voucher ID: BISH 553607) Taxon name on voucher: Hydrangea macrophylla subsp. macrophylla
State of Hawaii Hawaiian Islands	Kaua‘i Island		Bishop Museum (U.S.A. Hawaii. Honolulu.) (1986) (voucher ID: BISH 524408) Taxon name on voucher: Hydrangea macrophylla subsp. macrophylla
Japan (offshore islands) Ogasawara (Bonin) Islands	Bonin (Ogasawara) Islands	introduced	Kato, Hidetoshi (2007)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	New South Wales	introduced invasive cultivated	National Herbarium of New South Wales (2013) "Various cultivars commonly cultivated as garden ornamental shrubs; rarely naturalised".
Central America Central America (Pacific rim)	Guatemala (Republic of)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Central America Central America (Pacific rim)	Nicaragua (Republic of)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
China China	China (People's Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
China China	Hong Kong	introduced cultivated	Wu, Te-lin (2001) (p. 122) Ornamental.
Japan Japan	Japan	native	U.S. Dept. Agr., Agr. Res. Serv. (2013) Honshu
New Zealand New Zealand	New Zealand (country)	introduced invasive cultivated	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 757)
South America (Pacific rim) South America (Pacific rim)	Perú (Republic of)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	Comité français de l'Union Internationale pour la Conservation de la Nature en France (2013) envahissant
Seychelles Seychelles Islands	Seychelles Islands	introduced	Invasive Species Specialist Group (2017)

Control:  If you know of control methods for Hydrangea macrophylla, please let us know.