Since 1913 UK gardeners have welcomed a wealth of "alien" plant species from overseas to decorate their green spaces. Many are harmless but when some, such as the highly invasive Japanese knotweed, break out into the wider countryside they can have serious implications for our native environment.
The British Ecological Society (BES) is celebrating its centenary with an exhibit: "Have aliens landed in your garden?" at the RHS Chelsea Flower Show. Dr Ken Thompson reveals our changing tastes for exotic plants over the last 100 years and highlights some new and unexpected animal arrivals.Continue reading the main story