Alien invasion destroys pond life

It's plant-life, but not as we know it. Alien weeds are taking over rivers, streams and ponds, wreaking havoc and destroying indigenous plants. Britain's rarest flower is threatened, as are fish, amphibians and insects.

It's plant-life, but not as we know it. Alien weeds are taking over rivers, streams and ponds, wreaking havoc and destroying indigenous plants. Britain's rarest flower is threatened, as are fish, amphibians and insects.

The rise of alien species is blamed on the popularity of water features promoted in television garden shows, and the plants suggested for them. When they grow too much they are often discarded, with dramatic effects.

Environmentalists say all foreign invasive pond plants should be banned. The Consumers' Association will tell its hundreds of thousands of members next month, through its influential Gardening Which? magazine, to boycott foreign plants and to admonish any garden centres that sell them.

MPs are also demanding action to prohibit the sale of specific invasive plants. English Nature, which advises the Government on the environment, has lobbied for a change in the law. The Department for the Environment, Transport and the Regions has promised a review next year. Environmentalists say that could be too little, too late.

The Consumers' Association believes the growth in aquatic weeds has been fuelled by the boom in television gardening programmes which regularly promote water features. The invasive species sometimes used, mainly native to South America, Asia or Africa, are usually prettier than their British counterparts. But plants such as New Zealand pygmyweed, Parrot's feather (from Central America) or floating pennywort (from North and Central America), can rapidly grow out of control, turning a pretty garden pond into a heaving mass of dense foliage.

Amateur gardeners have been known to hack down the plants and - rather than destroy them, which is hard - dump them in a pond or river, where they swamp native plants. The plants do not need to be deliberately abandoned, however. The smallest fragment of a stem or leaf can migrate from the pond, via a bird's foot or a muddy boot.

The New Zealand pygmyweed Crassula helmsii, which has taken hold in about 1,000 sites up and down the country, is threatening the existence of the starfruit, Britain's rarest wild flower. A delicate white flower, it exists in only nine locations in the UK, and at five the pygmyweed is threatening to swamp it. On one pond near Esher in Surrey, volunteers maintain a vigil over the starfruit, keeping an eye on a neighbouring pond where pygmyweed has formed a blanket cover.

Dave Page, conservation officer with the local council, said: "It's very hard to kill off. The stems break into pieces and each tiny bit can grow again very quickly."

Martin Harper, of the wildplant conservation charity Plantlife, has compiled a report, At War with Aliens, which is being used to lobby the Government. "The only effective way to control these plants is to ban them," he said. "There is a consensus that they are one of the greatest problems facing our native biodiversity."

Mr Harper, Plantlife's conservation director, agrees with the Consumers' Association that the alien plants are taking hold so fast because of television exposure. He said: "[Presenters like] Charlie Dimmock have certainly made water gardening very popular and we are trying to encourage those television shows to have a responsibility to highlight the problems."

Ian Brownhill, Gardening Which? research manager, said: "These plants should not be available for sale and we urge our members and the general public not to buy them." A survey by the magazine revealed that 70 per cent of garden centres sell at least one of the plants "rarely with any label warning of their invasive nature".

A spokesman for Ground Force, the show featuring Ms Dimmock and Alan Titchmarsh, said it did not use specimens on an English Nature list of invasive plants.