Curly Waterweed (Lagarosiphon major)



Curly waterweed (Lagarosiphon major)

Photo courtesy of RPS Group PLC

To view NBN location data click here



  • Capable of forming very dense infestations in suitable habitats and occupying the full water column in waters up to 6m deep with significant impacts on native plants, insects and fish.
  • Classified as a serious threat to tourism, angling, boating and other recreational pursuits as well as conservation goals.
  • Sold in Garden Centres and/or aquarium trade.
  • Detached stems sink and can root from the nodes.
  • Spread by fragmentation via wind dispersal, boat movement, angling equipment and, possibly waterfowl.



Should not be released in the wild. Dispose of garden and pond waste responsibily. Check vehicles, boats, equipment and clothing for plant fragments when leaving infested sites and clean if necessary.

Physical Control

Is difficult as small fragments can easily break off, float away and rapidly reproduce. Hand pulling may, however, be effective for small infestations. In New Zealand, suction dredging using divers has helped with control.

Chemical Control

Through the use of herbicides is the preferred method of control in Britain. This has the disadvantage that other (native) flora can also be killed. More information on control measures is avaiable from the Centre for Ecology and Hydrology, Centre for Aquatic Plant Management Information Sheet (Click here to download)

Note use of herbicides in or near to water requires a licence from SEPA.

Biological Control

None known


Non Native Species Secretariat identification guideNon Native Species Secretariat Fact Sheet

SNH SAF Training Manual

Invasive Species Ireland Fact Sheet

Daisie Species Fact Sheets


Comments are closed.