Most Unwanted: Water primrose
Ludwigia grandiflora
Habitat: Freshwater
Threat: Clogs waterways and negatively impacts on native species and ecosystems
Status: Potential
Ludwigia grandiflora has not been recorded in the wild in Ireland to date. This species has become highly invasive and caused significant economic and environmental damage in many parts of the world including France and is now the subject of control measures in Britain. This species may also be known under two names L. peploides L. and L. uruguayensis L..
What is it?
Water Primrose is a perennial herb with powerful roots and stems that grow horizontally from the edges of the water body for 4 to 5 m. The species can grow vertically to about 1 m above the water surface making areas look like dry land. The species can also grow from very small fragments allowing new infestations to become established easily. It is a vigorous aquatic plant with bright yellow, showy flowers and willow-like leaves.
Impact
Ludwigia grandiflora can form very dense (almost impenetrable) mats in freshwater ecosystems. Large accumulations of this species can lead to a depletion of oxygen levels in the water while also competing with native species for space and resources. This species has been linked to significant losses in biodiversity at impacted sites in France.
This is an economic pest as it can clog waterways, drainage streams, bathing waters, and also impede boating
Where is it from?
Native to South America and some US states.
Where is it now?
This species is known from Britain where control measures are underway to prevent further spread and significant economic loss associated with this species. Ludwigia species have become naturalised in France where it has cost millions of Euro to the French economy.
How can it get here?
Popular garden pond and aquarium species.
What you can do
Do not buy any Ludwigia species. All species of Ludwigia are considered a threat to the environment.
If you are a garden centre manager remove all Ludwigia from sale.
Never dispose of garden or aquarium waste near waterways.
Report all sightings.
