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© JLCH Van Valkenburg
© JLCH Van Valkenburg
© T. Genty

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© T. Genty
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Myriophyllum heterophyllum

Identity

Common name: Variable watermilfoil
Origin: North America
Plant type: Herbaceous
Code of conduct: Annex I (consensus list)
Invasive status (ISEIA protocol): Black list
Main ornemental function: Plants for ponds

Description

This species looks similar to another invader : Myriophyllum aquaticum. Flexible plant, with tip often emerging above the water level when flowering. Leaves mostly submerged, opposite or in whorls of 4 to 6. Stem round, thick, reddish.

Spread

High dispersal potential. Vegetative reproduction by stem fragments. Fragments can be dispersed over long distances by water.

Habitat

M. heterophyllum grows in well-lit ponds, ditches, canals and slow-running streams. It is found growing under a wide range of chemical conditions, but tends to prefer acidic waters.

Impact

Species classified A1 in Belgium. Invasive in Germany. Variable watermilfoil is able produce very dense populations and high biomass. It is highly competitive and may lead to the exclusion of other submerged water plants. The dense mats it produces reduce sunlight and can restrict water movement; when decomposing, they alter water quality and reduce available oxygen. The low oxygen conditions can kill fish and harm other aquatic organisms. The plant can also cause boating and swimming hazards. For more information, click here

Recommendation

Do not plant, do not buy this species.

Possible native alternative

Main ornemental function

Plants for ponds

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