WATER fern, floating pennywort, parrot's feather and curly water-weed may look like decorative additions to garden ponds, but they can cause havoc in the wider environment.

Once released into the wild, they grow rapidly, taking over from native plant species in rivers, lakes and ponds, blocking out light and clogging up water treatment works.

Worcestershire Wildlife Trust, whose own nature reserves are affected by these plants, is supporting a campaign to persuade people not to stock, buy or spread them.

"Invasive plants can be present as fragments in other aquatic plants bought from garden centres and aquarium specialists," said Water for Wildlife's Andy Graham.

"Only a tiny piece is required to allow the plant to take over the whole waterway system."

For more information go to www.wildlifetrusts.org