Britain Bombarded by Invasive Plants

A recent study by the non-profit UK group Plantlife indicates that the invasion of non-native plants into Britain has been more successful than most people would expect. According to this article at Guardian Unlimited, the study divided Britain into over 3000 squares of land, and 82% of those blocks contained at least one of the top fifteen invasive plants. Interestingly, while some of the top species, like Japanese knotweed (Fallopia japonica), were introduced over a century ago, there are also successful invaders like Australian swamp stonecrop (Crassula helmsii, also known as New Zealand pygmy weed), which needed only 50 years to get to the top of the list, and floating pennywort (Hydrocotyle ranunculoides), which has only been in the UK since around 1990.