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© P. Brusselen
© P. Brusselen
© P. Brusselen
© E. Delbart

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© E. Delbart
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Aster novi-belgii

Identity

Common name: Michaelmas daisy
Synonyms: A. brumalis, A. floribundus, A. longifolius
Origin: North America
Plant type: Herbaceous
Life cycle: Perennial
Code of conduct: Annex II
Invasive status (ISEIA protocol): Watch list
Main ornemental function: Mixed border

Description

This factsheet is common for 3 North American aster species relatively similar, all listed as invasive : Aster lanceolatus, A. novi-belgii, A. x salignus. Herbaceous plants up from 0,9 to 1,5 m tall. Flower heads violet. Disk florests yellow and ray-florest violet. Leaves oval lance-shaped, entire or finely toothed, sessile. Flowering in autumn. A. lanceolatus can be distinguished from A. novi-belgii by the sessile leaves with rounded bases.

Spread

Medium spread potential. This plant reproduces only asexually by rhizomes. In Belgium, seeds are not viable in the wild, probably due to the late flowerinf of this species. Due to this strong vegetative development, North American asters can form quickly dense and extended colonies.

Habitat

American asters colonise both ruderal areas (wastelands, railways, roadways, etc.) and wetlands (riverbanks, megaphorbs, alluvial forests, wet meadows, etc.), especially on rich soils.

Impact

Species classified B3 in Belgium. Widespread throughout Europe. North American asters are listed as invasive in several European countries like France, Switzerland, Austria, Hungary. They can invade habitat of high conservation value like wetlands. Due to their strong vegetative development, North American asters can form dense and monospecific colonies displacing native plant species. Nevertheless, in Belgium, no populations of Aster novi-belgii are observed in natural habitats of ecological value. Its impacts seem limited. 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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