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Heracleum mantegazzianum

Identity

Common name: Giant hogweed
Origin: Asia (West Caucasus)
Plant type: Herbaceous
Life cycle: Bisannual to perennial
Code of conduct: Annex I (consensus list)
Invasive status (ISEIA protocol): Black list
Main ornemental function: Mixed border

Description

The giant hogweed is one of the largest herbs in Europe, up to 4 m tall and up to 10 cm in diameter. Leaves are divided and toothed. They can grow up to 3 m in length. The flowers are clustered in an umbrella-shaped head that is up to 80 cm wide. A total of 80.000 white coloured flowers can occur in one single plant.

Spread

The giant hogweed mainly spread by seeds. One individual can produce more than 10.000 seeds, dispersed at short distances by wind and long distances by water. The majority of the seeds fall within a distance of 4 m from the parent plant. This can lead to a natural progression of 10 meters per year.

Habitat

The giant hogweed mostly colonises riverbanks. It prefers moist and nutrient rich soils. Also found in grasslands, forest edges, tall-herb communities and ruderal areas (waste lands, railways, roadsides). Planted as ornamental, the species is frequent near houses.

Impact

Species classified A3 in Belgium. It is an aggressive invader all over Western Europe. Strong competitor for light. It can absorb up to 80% of light in dominant stands. Giant hogweed may reduce species richness and change the botanical composition of indigenous plant communities. The species is widespread in Belgium. Rivers are mostly impacted. The plant is a serious pulbic health issue. Its sap contains photosensitizing substances which may cause severe burns. Accident occurs frequenlty. For more information about this species, click here

Recommendation

Do not plant, do not buy this species.

Possible native alternative

Main ornemental function

Mixed border

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