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© E. Delbart
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Lemna minuta

Identity

Common name: Minute duckweed
Synonyms: Lemna minuscula
Origin: North America
Plant type: Herbaceous
Code of conduct: Annex II
Invasive status (ISEIA protocol): Watch list
Main ornemental function: Plants for ponds

Description

Aquatic plant floatting on the water surface. Leave elleptic to ovate, between 1 to 3 mm long, with unique nerve. No stems. One unique root of maximum 4 cm long.

Spread

High dispersal potential. The species mainly reproduces vegetatively by lateral budding. High growing rate. The species can be dissaminated over long distances by water birds, which transport plant fragments. Sexual reproduction is mentionned in the literature, but poorly known under Belgian climatic conditions.

Habitat

Lemna minor settles in shallow standing or slow flowing waters, often in shaded conditions. As for native Lemna species, it is found in meso- to eutrophic environments and is strongly resistant to pollution.

Impact

Species classified B3 in Belgium. Widespread in Flanders but less present in Wallonia. Impacts are similar to those of Azolla filiculoides. Outbreaks of Lemna minuta make dense floating mats at the water surface, that reduce light penetration and gas exchanges, causing the predominance of respiratory activities and the reduction in dissolved oxygen in water beneath the mats. As for native duckweed species, outbreaks are usually limited in time and space, depending on climatic conditions and levels of water eutrophication that often cause the disappearance of submersed macrophytes. Competition with native macrophytes is poorly documented but seems to be less severe than with other invasive aquatic plants. Waterfowl and Cyprinid fish are known to eat duckweeds to supplement their diet and may help to reduce outbreaks. For more information about this species, click here

Recommendation

Avoid planting this species near aquatic habitats (ponds, lakes, rivers, etc.) especially in the vicinity of protected areas (natural reserves, Natura 2000 sites, etc.).

Possible native alternative

Main ornemental function

Plants for ponds

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