Should we be worried about invasion by plants? Almost 4% of the plant species on earth can be found growing somewhere they didn’t start out, according to a new study. That’s about as many plant species as there are in the whole of Europe. These exotic flowers and leafy interlopers aren’t as innocent as they seem. We find out how experts at the Royal Botanic Gardens, Kew, are taking up arms to battle invaders in Britain and abroad.

Read the paper: Global exchange and accumulation of non-native plants