Himalayan balsam's pink flowers are an attractive sight on the river's edge but it is a menace that needs to be stopped in its tracks.

It is now threatening to choke off a section of the River Mead, in Westmead, West Swindon,which is an area popular with walkers.

The Swindon Water For Wildlife Project is calling for volunteers to help it clear this aggressive garden escapee from a stretch of river, which will culminate with a series of events beginning on Wednesday, June 23.

Himalayan Balsam's formal name among scientific circles is the Impatiens Glandulifera but it is also known more commonly among wildlife enthusiasts as Policeman's Helmet.

Swindon Water For Wildlife officer Jo Sayers said it can grow up to four metres tall and has an extraordinary reproductive system that makes it virtually unstoppable once it has set seed.

"It's actually a bit like a Busy Lizzie on steroids," she said.

"And it's a real threat to the wildlife on Swindon's riverbanks."

Himalayan balsam crowds out native plants such as comfrey and willow herb, which are both important food sources for insects.

Now the race is on to clear a stretch of the River Mead, where a blanket of Himalayan balsam is about to flower and just about to form the rocket-fuelled seed-pods.

If seeds are produced there is a real risk that they will get into the River Ray, one of the wildlife treasures of Swindon.

Ms Sayers, whose project is run by Wiltshire Wildlife Trust in partnership with Thames Water, the Environment Agency, Swindon Borough Council and the Great Western Community Forest, is leading a balsam-bashing work party on Saturday and needs all the volunteers she can get.

Gloves, coffee and biscuits will be provided for all who join in.

Telephone her on 01793 526229 for more information.