PRISONERS are helping to rid Portland of an unwanted invader.

They are taking part in a conservation project aimed at allowing rare flora and fauna to thrive.

The island is home to many endangered species of wildflowers, such as orchids and gentians, as well as lichens, liverworts and mosses threatened by an interloping plant.

Teams of conservation volunteers have started clearing the invasive cotoneaster in a three-year project to eradicate the plant, which is not native to this country. Tim Wilkins of the Plantlife conservation team, which is leading the project, said the thorny shrub posed a serious threat to the unique plants on Portland.

He said: “The island is one of only 150 such important sites in the world for rare plants. There are four species of lichen here which occur nowhere else in Britain. The cotoneaster is a very vigorous plant and really difficult to get rid of, it climbs over the rocks and suffocates natural species.”

Volunteers from Wild About Weymouth and Portland, Dorset Wildlife Trust, Dorset County Council’s adult services and the Young Offenders Institute have been helping to rip out the spiny plant – after it has been sprayed with environmentally- friendly weed killer – and burn the cuttings.

Mr Wilkins said: “We’re very lucky to have all these volunteers from different places helping us. It’s great we have the opportunity to work with the young offenders. They have done a lot of work on this site and absolutely loved it. It gives them the opportunity to give back to the community as well.”