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Helianthus tuberosus

Identity

Common name: Jerusalem artichoke
Origin: North America
Plant type: Herbaceous
Life cycle: Perennial
Code of conduct: Annex II
Invasive status (ISEIA protocol): Black list
Main ornemental function: Mixed border

Description

Helianthus tuberosus is an herbaceous plant, geophyte, with erect stems up to 3 m tall. Rhizomes with numerous potato-like tubers which persist throughout winter. Tubers are edible and serve as vegetable. Leaves mostly opposite, lanceolate long-pointed. Yellow flowers. Late flowering in Autumn (September to November).

Spread

Helianthus tuberosus mainly reproduces vegetatively by rhizomes. Because of late flowering, the plant produces few seeds. Maturation is usually interrupted by Autumn frost. Sexual reproduction is therefore very low. In the Summer, the plants produce tubers which allow the formation of new shoots the following Spring. This vegetative reproduction methods leads to dense stands. The tubers can also be spread by animals and water. Frequently planted as a vegetable before the second world war, and then abandonned, the species has survived and has continued to grow in the wild up to now.

Habitat

Riverbanks, alluvial soils. It prefers full sun conditions, moist and nutrient-rich soils, sandy to loamy. Intolerant to shade, the species is absent under canopy (alluvial forest). Also found on wastelands and abandonned fileds. Tubers are resistant to frost. The species is still used today as a vegetable.

Impact

Species classified A3 in Belgium. The plant can form dense, monospecific populations along rivers, where it outcompetes native species, alter vegetal successions by trees and favours river bank erosion. Helianthus can be very competitive in alluvial habitats. In some case, this species can be as competitive as Fallopia japonica. Widespread in Central Europe. Included in the black list in France, Germany, Austria, Hungrary, Italy, and in the watch list in Switzerland. It one of the most aggressive invader in some regions of Germany. Also invasive in North-Eastern France. In Belgium, large populations are present along rivers near the German border. For more information about this species, click here

Recommendation

(1) Avoid planting this species near rivers and wet habitats, especially in the vicinity of protected areas (natural reserves, Natura 2000 sites, etc.) ; (2) put a rhizome barrier in order to limit lateral expansion.

Possible native alternative

Main ornemental function

Mixed border

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