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Hydrangea macrophylla

Shrub up to 3 m tall with large leaves, and with groups of showy flowers that vary in color (pink, white, blue,…) depending on the soil pH.

Scientific name: Hydrangea macrophylla (Thunb.) Ser.

Common name: French hydrangea

Family: Hydrangeaceae

Status in Portugal: Invasive species in the Azores and on Madeira (listed in Decree-Law no. 92/2019, 10th July for the territory of Madeira) in mainland Portugal it is not common to find this plant out of cultivation.

Risk Assessment Score: 13 | Value obtained according to a protocol adapted from the Australian Weed Risk Assessment (Pheloung et al. 1999), by Morais et al. (2017), according to which values above 13 mean that the species has risk of having invasive behavior in the Portuguese territory | Updated on 30/09/2017.

Synonymy: Hydrangea macrophylla subsp. chungii (Rehder) E.M. McClint., Hydrangea macrophylla f. hortensia (Regel) Rehder, Hydrangea macrophylla var. macrophylla

Last update: 28/11/2016 ! Profile prepared by the LIFE+ Terras do Priolo project team.

Help us map this species on our citizen-science platform.

Avistamentos actuais da espécie: 
Family: 
Hydrangeaceae
Appearence: 
Trees and shrubs

How to recognize it

Ascending to erect, vigorous, deciduous, densely branched, whitish shrub.

Leaves: opposite, simple, ovate and acute with serrated margins. Its size can reach 20 cm.

Flowers: they assemble in a corymbose summit; the flowers on the periphery may be fertile or sterile. It has 4 sepals, white, blue, purple or pink, depending on the soil pH, and 5 petals, normally blue.

Fruits: small capsule less than 5 mm.

Flowering: from May to July.

Similar species

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Characteristics that aid invasion

The species reproduces vegetatively through plant fragments. Its dispersion is made from small fragments by hydrochory and/or facilitated by very frequent planting.

 

Native distribution area

China, Japan, and Korea.

Distribution in Portugal

Minho (Mainland Portugal) and Azores and Madeira Archipelagos.

For more detailed locations of this species, check the online interactive map. This map is still incomplete – we need your help! Contribute by submitting records of the location of the species where you can find it.

 

Geographic areas where there are records of Hydrangea macrophylla (Thunb.) Ser.

Other places where the species is invasive

Northern Spain and New Zealand.

Introduction reasons

The introduction was intentional to subdivide the land and grow hedges.

Preferential invasion environments

Abandoned pastures, steep slopes, trails where vegetation is low and sparse. Very common in laurel forests, juniper groves, peatlands and along streams.

 

Impacts on ecosystems

The species can alter soil morphology and its dense patches alter the structure, abundance and ecological succession of the ecosystems it invades. It prevents the development of native vegetation and reduces species diversity through competition and recruitment.

Economic impacts

Potentially high costs in applying control measures.

Natura 2000 Network habitats more prone to impacts

– Sphagnum Active raised bogs (7110);

– Sphagnum Blanket bogs (7130);

– Wooded bogs (91D0).

Controlling an invasive species demands a well-planned management, which includes the determination of the invaded area, identifying the causes of invasion, assessing the impacts, defining the intervention priorities, selecting the adequate control methodologies and their application. Afterwards it is fundamental to monitor the efficiency of the methodologies and recuperation of the intervened area as to perform, whenever necessary, the follow-up control.

The control methodologies used for Hydrangea macrophylla include:

Physical control

Hand pulling:  the manual method is most effective for areas with little invasion and/or small plants. The entire plant must be removed (leaves, inflorescence and rhizome), leaving no residues and/or fragments to prevent their regeneration. The manual method requires labor and work time; however, is the most viable and advisable in easy-access places, with low erosion risk or where small patches occur close to populations of rare and endangered species. Plant residues/fragments can be left in place to dry. The removal should be carried out with wet weather and moist soil to facilitate root removal.

Visit the webpage How to Control for additional and more detailed information about the correct application of these methodologies.

DAISIE European invasive">Invasive Alien species">Species Gateway (2012) Hydrangea macrophylla (Thunb.) Ser.. Disponível: http://www.europe-aliens.org/speciesFactsheet.do?speciesId=17202 [Retri... 08/10/2015].

Silva L, Corvelo R, Moura M, Fernandes FM, Ojeda Land E (2008) Hydrangea macrophylla (Thunb.) Ser. In: Silva L, E Ojeda Land & JL Rodríguez Luengo (eds.) Flora e Fauna Invasora da Macaronésia. TOP 100 nos Açores, Madeira e Canárias, pp. 251-254. ARENA, Ponta Delgada.

Schäfer H (2005) Flora of the Azores. A Field Guide. Second Enlarged edition. Margraf Publishers, Weikersheim.

Jeménez S, Coelho R, López Y, Silva C (2013) Guia de Controlo de Espécies Exóticas invasoras">Invasoras. Sociedade Portuguesa para o Estudo das Aves, Lisboa.

The Plant List. Hydrangea macrophylla. Disponível: http://www.theplantlist.org/tpl1.1/search?q=Hydrangea+macrophylla [Retr... 08/10/2015].