Water primrose

Ludwigia grandiflora

Overview

Habitat: Still or slow flowing freshwater habitats

 

Description: 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.


Origin and Distribution: Native to South America and some US states. This species is now known in 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.

 

Impacts: 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

 

Is it found in Ireland? Ludwigia grandiflora was identified in a series of isolated ponds on the south west coast of Ireland. The species is not yet found in the wild on the Island of Ireland.

 

How might it get into the wild Here? The aquaria trade is the most likely pathway for introduction of Ludwigia grandiflora.

 

Prevent Spread

  • Promote native species and biodiversity - use alternative, native plants
  • Know what you are buying/growing and source native Irish seed and plants
  • Do not swap plants and cuttings
  • Clean plants before adding to ponds (dispose of water away from water courses)
  • Follow control advice and watch out for hitchhikers - inspect new imported purchases for invasive pest and pathogens
  • Clean equipment before moving between waterbodies
  • Never collect plants from the wild
  • Safe disposal of plant material and growing media

 

Invasive Species Ireland

Invasive Species Ireland