Exactly, EBarnacle, and also grass and prairie gardens (for example Beth Chatto's wonderful drought garden here in England) which are designed with North American plants. Even Lavender is not native to the UK. If one eradicated all these non-natives, where would we be? I just couldn't bear to lose all the delightful species of plants from around the world for this cause. The people at Kew would have forty fits! Last century, plant collectors went to the four corners of the Earth to bring us new examples. And plant breeders have devoted their lives to cultivating them. I don't feel I can agree with this purist viewpoint. But I do respect the concern for native wildlife and for maintaining the balance of Nature.