Managing floating pennywort – how you can help

Floating pennywort forms dense mats which resemble a solid surface making them a potential hazard to animals and people. Image: Trevor Renals.

What is floating pennywort and why is it a problem?

Floating pennywort is a highly invasive aquatic plant that was first introduced to Britain as an ornamental pond plant in the 1990’s. In the wild, this species can grow up to 20cm a day and rapidly forms dense floating mats of weed across waterbodies. These crowd out native species, block light impacting on the aquatic ecosystem, interfere with activities such as angling, paddling and sailing, and potentially increase the flood risk.

Unless effective management is undertaken it is likely that this species will spread across most of the country. There is already a lot of effort spent managing floating pennywort, during 2017 the EA removed over 1000 tonnes from the Rivers Cam and Ouse alone, but no single organisation is responsible for managing this species and the best approach is through partnerships.

The GB Floating Pennywort Strategy

A national partnership has been formed between government and non-government organisations to facilitate the local groups engaged in floating pennywort management:

  • Angling Trust
  • British Canoeing
  • Open Water Swimming Society
  • British Rowing
  • Canal and River Trust
  • Water companies
  • Inland Drainage Boards
  • Environment Agency
  • Defra
  • GB NNSS
  • Welsh Government
  • Natural Resources Wales
  • Natural England
  • CINNG (Community Invasive Non-native (Species) Group)
  • SEPA
This partnership has agreed a strategy to manage floating pennywort and produced guidance and resources to support local partnerships develop a Floating pennywort Catchment Management Plan.

What can I do to help?

If you would like to get involved in protecting your watercourses from floating pennywort there are a number of things you can do:

Image: British Canoeing

  • Join a Local Action Group working on invasive species management. If you have one in your area, LAGs are always keen for volunteers and new members.
  • Get involved with invasive species management through your sport. There are a number of organisations, such the British Canoeing and The Angling Trust that are very active in supporting their members with floating pennywort management plans. Find a relevant body under Useful contacts below to join and get involved in a range of activities. It’s a great way to learn more about your sport and meet people with similar interests in your area.
  • Record floating pennywort and other invasive species online via iRecord (external link). Good survey data is critical to management. Download an ID guide for floating pennywort (PDF) to help you.
  • Check Clean Dry boats, clothing and equipment after leaving the water. Floating pennywort can spread from a tiny plant fragment and is easily transferred between waterbodies on damp boats, clothing and equipment.

Useful contacts

  • Floating pennywort Strategy steering group:    
  • Angling Trust: website  |      
  • British Canoeing: website |   
  • Canal & River Trust: website
  • Environment Agency: website
  • GB Non-native Species Secretariat: website |

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