Cool! I only asked as I've just finished reading Tim Low's books 'New Nature' and 'Feral Future' which concentrate a lot on introduced species in Australia and I was blown away at how many there were. So, I was interested to see whether the UK has similar issues. I've heard of things like Japanese Knotweed and Himalayan Balsalm but I guess there are a few more, some of which will be toxic.
Australia's situation is absolutely unique, because of its status as an island continent which was seperated from the rest of the world for so long. This makes the australian ecosystem uniquely vulnerable to aggressive invasion by introduced alien species. Another way to put this is that the ecosystem of somewhere like the UK is a lot more resilient to this sort invasion, and therefore the only plants which manage to get themselves established are either
very aggressive or able to survive in extremely hostile environments. Japanese knotweed is a perfect example, whose name in Japanese means "the iron one" because it can split concrete and is almost impossible to exterminate. Another good example is buddliea, whose natural home is bare Himalayan rock slopes. This plant can be found in the UK growing as a small tree out cracks in masonry, far away from any soil and surviving on rainwater it can suck in the brief period when the masonry is wet, and has colonised the entire railway network. But if you just go out into the countryside, almost everything you find will be native. Simply being toxic isn't enough for most of them to gain an advantage over the native wildlife.
Further, are there any introduced species that have proved useful from a bushcraft point of view? One for another thread I think or I'll get shouted at for hijacking this one.
There are no doubt a few. One is
Lepidium draba or "Hoary Cress", which is an edible introduced species (a green vegetable, not a berry) that is currently spreading north-west from its original introduction site on the isle of Thanet (also sometimes called "Thanetweed").
Another good one is Alexanders (
Smyrnium olusatrum) which was deliberately introduced as a vegetable by the Romans and still grows wild all around the coast of the UK. There are a number of other herbs and vegetables that currently grow wild in the UK which were supposedly brought here by the Romans. However, given that the Romans did not come very far and that the climate has been warming (on average) since then, it is possible that some of these species would eventually have arrived on their own. None of these cause the sort of havoc created by Japanese knotweed or the many disastrous introductions of alien species into Australia.
