Gardeners with ornamental ponds and tropical fish hobbyists are being asked to join a Government backed scheme launched today to prevent invasive plant species spreading into the wild and clogging up our rivers and lakes.

Many people – and anglers in particular – will be aware of Japanese knotweed, a plant with pretty pink and white flowers that was introduced to Britain for its ornamental properties but has now become a menace along thousands of miles of river bank.

But the English environment department Defra and the Scottish government are concerned that there are several other major threats to our rivers from plants bought for ornamental garden ponds or to decorate fish aquariums.

Today, the Be Plant Wise campaign was launched on both sides of the border to warn gardeners and tropical fish enthusiasts that there are other plants that, if allowed to escape into the wild, could do immense damage.

Says a Defra statement: “The Be Plant Wise campaign highlights five of the worst offenders currently wreaking havoc on our wildlife and waterways. Gardeners can often unwittingly exacerbate the problem by disposing of unwanted pond plants without composting them properly, throwing out pond water or fish tank water incorrectly, or accidentally introducing species to the wild.

“A whole river can be strangled just from one fragment of plant. Fast-growing floating pennywort, New Zealand pigmyweed, water-primrose, parrot’s feather and water fern – all of which could be found in your garden pond - are some of those named as posing significant problems in the wild with the potential to cost the nation millions of pounds if they continue to expand at their current rate.

“Floating pennywort can grow at a rate of 20cm a day in the wild and water primrose can double in size every 15-20 days. Many of these plants grow to such an extent that they form dense mats which can look like dry land and so pose an additional danger of drowning to people and livestock.”

Visit www.direct.gov.uk/beplantwise for more information in England, or in Scotland visit www.scotland.gov.uk/beplantwise