Home About BFIS Species List Risk Analysis Harmonia⁺ Resources Outputs Mailing List Registry
Contact us  |  Login  | 
© Etienne Branquart, Belgian Biodiversity Platform
© Vilda
© Etienne Branquart, Belgian Biodiversity Platform
© Etienne Branquart, Belgian Biodiversity Platform
© Etienne Branquart, Belgian Biodiversity Platform
Fallopia japonica - Japanese knotweed

Synonym: Polygonum cuspidatum, Reynoutria japonica.
French name:  Renouée du japon
Dutch name: Japanse duizendknoop
Family: Polygonaceae
Group: Vascular plants
Origin: Asia
Habitat: terrestrial
Introduction:  agri- and horticulture
ISEIA Score : 12
Naturalization in Belgium
First observation in the wild: 1888
Invasion stage: spread
Spatial distribution: widespread
Reproduction in the wild: yes
Dispersion potential: high
Natural habitats: high
More on invasiveness: As other Asiatic knotweeds, Japanese knotweed colonises a wide range of environments, with a predilection for moist and nitrogen-rich soils. It prefers sunny places or semi-shaded habitats. This pioneer plant proliferates both in ruderal and semi-natural habitats, including riparian areas and open forests. It doesn't produce any seed and reproduces clonally. Stem and rhizomes may easily split in small pieces; fragments are able to regenerate a plant, provided a node is present. Transport of garden waste and soil contaminated with rhizomes are the major dispersal modes. Where the plant is widely consolidated on river banks it is also spread by floods and can easily colonise downstream.
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 ():
grasslands: 64306510
forest habitats: 91E0*91F0
Impacts on Species
Predation / Herbivory: low
Competition: high
Disease transmission: low
Genetic effects: low
Impacts on Ecosystems
Nutrient cycling: high
Physical alteration: high
Natural successions: high
Food web alteration: low
More on impacts: Fallopia japonica is able to monopolize space and to form dense and persistent populations. It can outcompete most of native herbaceous plant species thanks to early seasonal development, high growth rate and productivity, abundant leaf cover, allelochemical production and clonal spread associated with an extraordinarily high rate of proliferation of below-ground organs. It also decreases soil bulk density and pH, increases organic matter content and enhances nutrient cycling rates, probably due to nutrient uplift. Its development reduces plant and invertebrate species diversity, alters habitat for fish and wildlife, change light and energy conditions of the ecosystem and favours river bank erosion during the winter. Prolific rhizome and shoot growth can damage foundations, walls, pavements, and drainage works, and causes flood hazards by increasing resistance to water flow and damaging flood prevention structures.
Data Source & References
Authors: Branquart Etienne, Vanderhoeven Sonia, Van Landuyt Wouter, Van Rossum Fabienne, Verloove Filip
Published on:  21 November 2007
Last update:  16 December 2010
Aguilera, A.C., Alpert, P., Dukes, J.S. & Harrington, R. (2010)
Impacts of the invasive plant Fallopia japonica (Houtt.) on plant communities and ecosystem processes.
Biologicial Invasions 12:1243–1252
Alberternst, B. & Böhmer, H.J. (2006)
Invasive alien species fact sheet, Fallopia japonica.
From online database of the North European and Baltic network on invasive alien species (NOBANIS).
Barney, J.N., Tharayil, N., DiTommaso, A. & Bhowmik, P.C. (2006)
The biology of invasive alien plants in Canada. 5. Polygonum cuspidatum Sieb. & Zucc.
Canadian Journal of Plant Sciences 86: 887–905.
Bimova, K., Mandak, B. & Kasparova, I. (2004)
How does Reynoutria invasion fit the various theories of invasibility?
Journal of Vegetation Science 15(4): 495–504.
Bímová, K., Mandák, B. & Kašparová, I. (2004)
How does Reynoutria invasion fit the various theories of invasibility?
Journal of Vegetation Science 15(4): 495–504.
Dassonville, N., Vanderhoeven, S., Gruber, W. & Meerts, P. (2007)
Invasion by Fallopia japonica increases topsoil mineral nutrient concentrations.
Ecoscience 14: 230-240.
De Waal, L.C. (2001)
A viability study of Fallopia japonica stem tissue.
Weed Research 41(5): 447–460.
Gerber, E., Krebs, C., Murrell, C., Moretti, M., Rocklin, R. & Schaffner, U. (2008)
Exotic invasive knotweeds (Fallopia spp.) negatively affect native plant and invertebrate assemblages in European riparian habitats.
Biological Conservation 141: 646-654.
Hejda, M., Pysek, P. & Jarosik, V. (2009)
Impact of invasive plants on the species richness, diversity and composition of invaded communities.
Journal of Ecology 97: 393–403.
Kappes, H., Lay, R. & Topp, W. (2007)
Changes in different trophic levels of litter-dwelling macrofauna associated with giant knotweed invasion.
Ecosystems 10: 737-744.
Krebs, C., Mahy, G., Matthies, D., Schaffner, U.,Tiébré, M.-S. & Bizoux, J.-P. (2009)
Taxa distribution and RAPD markers indicate different origin and regional differentiation of hybrids in the invasive Fallopia complex in central-western Europe.
Plant Biology
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.
Muller, S. (2004)
Plantes invasives en France : état des connaissances et propositions d'actions.
Publication scientifique du Museum d'Histoire naturelle, Patrimoines naturels n°62.
Tiébré, M.-S., Bizoux, J.-P., Hardy, O.J., Bailey, J.P. & Mahy, G. (2007)
Hybridization and morphogenetic variation in the invasive alien Fallopia (Polygonaceae) complex in Belgium.
American Journal of Botany 94: 1900–1910.
Tiébré, M.-S., Vanderhoeven, S., Saad, L. & Mahy, G. (2007)
Hybridization and sexual reproduction in the invasive alien Fallopia (Polygonaceae) complex in Belgium.
Annals of Botany 99: 193–203.
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.
Vanderhoeven, S., Dassonville, N. & Meerts, P. (2005)
Increased topsoil mineral nutrient concentrations under exotic invasive plants in Belgium.
Pland and Soil 275: 169-179.
Verloove, F. (2006)
Catalogue of the Neophytes in Belgium (1800-2005).
Scripta Botanica Belgica 39, 89 pp.
Weber, E. & Gut, D. (2004)
Assessing the risk of potentially invasive plant species in central Europe.
Journal for Nature Conservation12: 171-179.
Other Internet Links

© 2000-2023 by the Belgian Biodiversity Platform