It might look pretty but an alien plant is stifling natural life along Dorset’s rivers.

The Himalayan balsam is leading an invasion of our waterways and Dorset Wildlife Trust and Dorset Farming and Wildlife Advisory Group are fighting back.

Return of the Natives is a three-year project to remove the plant from the Frome, the Bere Stream and the Moors River and their tributaries and to examine the extent of the threat from other alien plants.

Top of the hit list is the successful Himalayan balsam, now the fastest growing annual plant in Britain.

Originally brought here by the Victorians, each plant can produce up to 800 seeds and can grow to a height of three metres, shading out all native plants. And once it has killed them, with their stabilising root systems, river banks become vulnerable to erosion.

“We need to do something about these aliens now,” said Sarah Williams, conservation officer for the trust. “Himalayan balsam already has a foothold on Dorset’s rivers, but if we act now we can stop it.

“We are calling on volunteers who would like to help us in the task, which will start at the head of the rivers and work downstream, as otherwise the seeds could be carried down to new sites.

“Dorset has wonderful rivers for wildlife – let’s keep it that way.”

Other aliens under investigation are skunk cabbage and monkey flower, which are both sold as aquatic plants. The trust recommends native plants such as meadowsweet, purple loosestrife, marsh marigold and water forget-me-not.

The project was launched on Tuesday on the River Hooke, a tributary of the Frome, near Dorchester, with a well attended working party.

More will be held and for future dates contact Sarah Williams on 01305 264620.