Detailed view

© S. Vanderhoeven
© S. Vanderhoeven
© S. Vanderhoeven
© S. Vanderhoeven
© E. Delbart

Invaded site

© S. Vanderhoeven
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Impatiens glandulifera

Identity

Common name: Himalayan balsam
Synonyms: Impatiens roylei
Origin: Asia
Plant type: Herbaceous
Life cycle: Annual
Code of conduct: Annex I (consensus list)
Invasive status (ISEIA protocol): Black list
Main ornemental function: Mixed border

Description

Herbaceous plant up to 2,5 m tall with purplish hollow stems. Leaves lanceolate to elliptic, with serrate margins. Base of the leaves glandular. Large pink to purple flowers. Fruits are capsules of 5 cm long, green coloured.

Spread

High dispersal capacities. The species can produce a high number of seeds (up to 800 per plant). Seeds are expelled at a few metres (up to 7 m) by explosion of the fruit at maturity. Seeds can be trasported over long distances through rivers. Seeds can survive 3 years in the soil. The plant also reproduces vegetatively by stem and root cuttings. Fragments of plants can easily re-grow. Frenquently planted as ornemental and honey plant for bee-keeping. Seeds are still distributed through seeds trade.

Habitat

Riverbanks and riparian vegetation are the main habitat invaded. Also present in forest habitats (forest edges, floodplain forest, forest gaps), wet meadows and megaphorbs, wet disturbed places. I. glandulifera grows on a wide spectrum of habitats, but has a preference for shaded sites on moist and nutrient-rich soils.

Impact

Species classified A3 in Belgium. Widespread in Belgium, this species is mentionned as invasive in numerous countries of Western and Central Europe. I. glandulifera may form dense monospecific stands that cover the soil, shade out and replace native annual and even perennial plant species because of early germination and rapid growth. In some conditions, it can reduce local species richness. In the Czech Republic, I. glandulifera covers 56 % of the rivers length. Due to a constant rate of spread, the species is expected to to cover all rivers of the country in 2025. However, impacts of the himalayan balsam on native flora is controversed. Negligible effect on riparian communities have been observed. Very attractive flowers for insects. Dense populations of I. glandulifera may cause diversion of insects from pollinating native flora. 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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