@Claire: I hope a sure id comes in from another YGS member, but meanwhile, yours sounds likely. If it's already happy on your damp clay why would it go away? To have more, let it make seeds and learn to know the seedlings and transplant them. Or start the seeds yourself. Maybe you have a unique plant and your seedlings will be wonderful? Something like that happened in my garden with a peony seedling. It turned into a peony like no other. It might even be interesting to peony growers. We'll see.