I know, I know. But I was attracted by it's very bold foilage and thought it would look nice next to the pond, which it does. But it's a colonizer, or a nice name for an aggressive spreader.
My pet goldfish love the Plume Poppy
I'll keep it but must work a little harder to control its spread. That goes for the artemesia as well as the spiderwort and a whole long list of other invasive plants : Spiderwort, Rudbeckia, Korean bellflower, Cranesbill Geranium, Feverfew. Did I leave anything out ?