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© S. Vanderhoeven
© S. Vanderhoeven
© S. Vanderhoeven
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Fallopia x bohemica

Identity

Common name: Bohemian knotweed
Origin: Asia
Plant type: Herbaceous
Life cycle: Perennial
Code of conduct: Annex I (consensus list)
Invasive status (ISEIA protocol): Black list
Main ornemental function: Mixed border • Cover ground

Description

This factsheet is common for 3 Fallopia species listed as invasive : Fallopia japonica, F. sachalinensis, F. x bohemica. F. x bohemica is the hybrid between F. japonica and F. sachalinensis. Herbaceous perennial with robust, erect stems with distinct nodes like bamboo, up to 4 m tall and an extensive system of rhizomes. These rhizomes can be 15-20 m long and can penetrate to 3 - 7 m deep in the soil. Leaves of F. x bohemica are characterised by intermediate morphological traits between its two parents. White flowers.

Spread

High vegetative multiplication capacities. Strong aptitudes of lateral expansion by rhizomes : rhizomes can spread up to 1 m/year. Small rhizomes fragments of a few grammes can regenerate the whole plant. Regeneration rate is higher for F. x bohemica than its two parents. Rhizome fragments can be dispersed over long distances through rivers or soil transports. Stems fragments can also regenerate the plant, specially from the nodes. The plant grows fastly. Human-transported soil contaminated with rhizomes is the major dispersal vector. Sexual reproduction may also occurs, but is less frequent. In Belgium, seedlings of knotweeds are rarely observed in nature.

Habitat

Fallopia species can grow in a wide array of habitats, with a preference for wet, nitrogen-rich soils e.g. river banks and alluvial zones. Also frequenlty found along railways and roads.

Impact

Species classified A2 in Belgium. Knotweeds are recognized as aggressive invaders throughout Western, Central and Northern Europe. They form very dense populations which outcompetes native vegetation, reduces species richness and modifies soil properties. Fallopia species produce allelopathic substances which inhibit the growth of native species. Nutrient cycling is also modified in invaded areas. Due to its high growing rate and vegetative multiplication capacities, management of Fallopia populations is very difficult. Stands of knotweed along rivers encourage bank erosion. Prolific rhizome and shoot growth can damage infrastructures like foundations, walls, etc. For mode information about this species, click here

Recommendation

Do not buy or plant this species.

Possible native alternatives

Main ornemental function

Mixed border
Cover ground

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