A lot of people think of plants as pretty to look at, but defenceless and passive as far as organisms go. However, the many alien species – or “monster plants” – around us show we should never underestimate plants and the fascinating battles that go on beneath our feet. Many of the first alien plants – those introduced by humans outside their natural range – to arrive in the UK were brought back by plant hunters of the Victorian era. Plants have adapted over millennia to their environment. So, we would expect alien plants to struggle in new places. But…