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© Gérald Duhayon, Parc Naturel des Plaines de l'Escaut
© Silvia Meijer
© Silvia Meijer
© Vilda
© Etienne Branquart, Belgian Biodiversity Platform
Hydrocotyle ranunculoides - Water pennywort

French name:  Hydrocotyle fausse renoncule
Dutch name: Grote waternavel
Family: Apiaceae
Group: Vascular plants
Origin: North America
Habitat: freshwater
Introduction:  aquariums and ponds
ISEIA Score : 12
Naturalization in Belgium
First observation in the wild: 1992
Invasion stage: spread
Spatial distribution: restricted
Reproduction in the wild: yes
Dispersion potential: high
Natural habitats: high
More on invasiveness: H. ranunculoides thrives in slow-flowing water bodies, particularly ditches, canals, lakes and ponds. It prefers eutrophic waters with a high content of nitrate, phosphate and/or organic matter. It can also colonise marshes and mesotrophic water bodies.
Distribution in Belgium
Established populations
absent from district
isolated populations (1-5 localities per district)
widespread (>5 localities per district)
Endangered areas
low risk
medium risk
high risk

Endangered Natura 2000 habitats ():
freshwater habitats: 3130315032603270
Impacts on Species
Predation / Herbivory: low
Competition: high
Disease transmission: low
Genetic effects: low
Impacts on Ecosystems
Nutrient cycling: likely
Physical alteration: high
Natural successions: high
Food web alteration: low
More on impacts: H. rancunculoides forms dense interwoven mats of vegetation which can quickly cover the water surface (under UK conditions floating carpets have been observed to grow up to 15 meters from the bank in a single season). Due to its vigorous growth, this plant causes loss of light and reduction in dissolved oxygen content. As a consequence, the native submerged and water-edge plant species can be outcompeted and ecosystem functions can be altered.
Data Source & References
Authors: Branquart Etienne, Stiers Iris, Triest Ludwig, Vanderhoeven Sonia, Van Landuyt Wouter, Van Rossum Fabienne, Verloove Filip
Published on:  29 October 2007
Last update:  11 December 2013
AEF (2006)
Cartes provisoires de la distribution de néophytes en Wallonie.
Unpublished document.
Baas W.J. & Duistermaat L.H. (1999)
De opmars van grote waternavel Hydrocotyle ranunculoides in Nederland, 1996-1998.
Gorteria 24: 77-82.
Baker R. et al. (2007)
Opinion of the scientific panel of plant health on the pest risk analysis made by EPPO on Hydrocotyle ranunculoides.
EFSA Journal 468: 5-13.
Denys, L., Packet, J. & Van Landuyt, W. (2004)
Neofyten in het Vlaamse water : signalement van vaste waarden en rijzende sterren.
Natuur.focus 3(4): 120128.
EPPO (2006)
Data sheets on quarantine pests: Hydrocotyle ranunculoides
OEPP/EPPO Bulletin 36: 3-6.
Huckle J. (2002)
Invasive alien aquatic plant species, Hydrocotyle ranunculoides.
Invasive Alien Species Project. Fact Sheet 2. English Nature & University of Liverpool.
Hussner, A. (2009)
Growth and photosynthesis of four invasive aquatic plant species in Europe.
Weed Research 49: 506-515.
Hussner, A. (2007)
Zur Biologie des aquatischen Neophyten Hydrocotyle ranunculoides L. f. (Apiaceae) in Nordrhein-Westfalen.
Flor. Rundbr. 40: 19-24.
Lambinon, J., Delvosalle, L. & Duvigneaud, J. (2004)
Nouvelle fore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des régions voisines.
Editions du Patrimoine du Jardin botanique national de Belgique, Meise.
Newman J.R. (2006)
Information sheet 24: floating pennywort.
Aquatic Plant management Group, CEH Wallingford.
Newman J.R. & Dawson F.H. (1999)
Ecology, distribution and chemical control of Hydrocotyle ranunculoides in the UK.
Hydrobiologia 415: 295-298.
Nijs, I., Verlinden, M., Meerts, P., Dassonville, N., Domken, S., Triest, L., Stiers, I., Mahy, G., Saad, L., Lebrun, L., Jacquemart, A.L. & Cawoy, V. (2009)
Biodiversity impacts of highly invasive alien plants: mechanisms,enhancing factors and risk assessment – Alien Impact.
Final report phase 1, BELSPO contract number SD/BD/01A ,Brussels, 50 pp.
Smith, I.M., McNamara, D.G., Scott, P.R. & Holderness, M. (1997)
Quarantine Pests for Europe.
CABI International, Wallingford, UK, 1425 pp
Thiébaut, G. (2007)
Non-indigenous aquatic and semiaquatic plant species in France.
In: F. Gherardi (Ed.), Biological invaders in inland waters: profiles, distribution and threats, Springer: 209-229.
Toussaint, B. & Bedouet, F. (2005)
Les espèces végétales invasives des milieux aquatiques et humides du bassin Artois-Picardie.
Agence de l'Eau Artois-Picardie, 38 pp.
Van Landuyt, W., Hoste, I., Vanhecke, L., Van den Bremt, P. Vercruysse, W. & De Beer, D. (2006)
Atlas van de Flora van Vlaanderen en het Brussels gewest.
Nationale Plantentuin en het Instituut voor Natuur- en Bosonderzoek i.s.m. Flo.Wer vzw.
Veraart B. & Soens D. (2005)
Invasieve watergebonden plantensoorten bedreigen ons watersysteem.
Nieuwsbrief Water 18 ( Juli-Augustus 2005): 1-6.
Verloove, F. (2006)
Catalogue of the Neophytes in Belgium (1800-2005).
Scripta Botanica Belgica 39, 89 pp.
Verloove, F. (2010)
Hydrocotyle ranunculoides.
In: Manual of the Alien Plants of Belgium [available online], National Botanic Garden of Belgium.
Verloove, F. & Heyneman, G. (1999)
Hydrocotyle ranunculoides L.f. (Grote waternavel), snel uitbreidend in de omgeving van Gent (Oost-Vlaanderen, België).
Dumortiera 74: 16-20.

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