Rising temperatures are boon to exotic invaders

Plants from semi-tropical climes are overtaking native British species and choking habitat as they flourish in warmer conditions

A half-degree increase in the average temperature in September and October in East Anglia this century has made an already troublesome plant invader even more of a nuisance. While the change in climate has been hardly noticeable to humans, it has made an enormous difference to the floating pennywort, Hydrocotyle ranunculoide, which already threatens to choke slow-moving rivers and the Broads.

The extension of warmer weather into autumn has give this semi-tropical South American plant the opportunity to produce viable seeds for the first time enabling it to spread even faster.