There is a large number of aliens plants growing wild in Ireland. I guess that really the definition of alien plant depends on far back you wish to go – if you go back far enough even Ash trees are alien.
In recent years there has been an increase in alien plants growing wild due to garden escapees and seeds that travel to the country in the transport of fruit and veg from abroad.
Around where I live there is a lovely little alien, called Indian Balsalm, which apparently has made it’s way across the country from Belfast according to Flora Hibernica, The wild flowers, plants and trees of Ireland by Jonathan Pilcher & Valerie Hall.
Last year I noticed this plant on the lower reaches of the hill that we live on and this year the plant has moved further up the hill.
There is a lovely little hoverfly on one of the flowers, quite undisturbed by my attention. Next year I expect to see the plants much further up the hill and closer to our home.
There is nothing that can be done really in rural Ireland to prevent the spread of these new plants, at least the Indian Balsalm is a pleasing looking plant to my eye, compared to the Japanese knotweed.
I live in Florida, in the US. We have invasive species here such as the Australian pine tree, the melaleuca tree and the Brazilian pepper that choke out the local species and generally take over the landscape. In addition we have a brown South American anole that has crowded out Florida’s native green anole. I’ve been living here 4.5 years and only ever saw two green anoles – the rest, literally thousands, have all been brown.