Gardeners across the UK are being urged to go outside and look for a potentially dangerous plant before winter's chilly weather arrives. Japanese knotweed is an extremely invasive species that spreads easily, whether through disrupted earth or pieces dropping from a neighbour's garden. It's believed to exist in roughly five out of every 100 gardens throughout the UK. However, despite being widely known, it's often confused with ordinary plants sharing similar features. Mistaking knotweed for an