But, as katlaughing said, thistles have a place as well. After all, the thistle is the national flower of Scotland.

I remember many years ago my father, whose ten years dead now, who was a keen gardener came to visit us and we were pottering around in the garden. And there was this enormous thistle with a great purple head, and he was going to cut it and then he spotted some indication on my part that I liked the look of it, so he went and found a plastic bag, and fixed it over the head so it'd still be there, but it wouldn't spread its seeds.

I've often thought it showed a rare sensitivity and tolerance on his part. We need more of that in the world, and here is a good place to practice it.