Thanks, Lori, you're good! Yes, you're right, I can see it now. I'd never have recognized it without the flowers. Zone 4 would seem to be out of its listed range, perhaps city heat island effect (it's in Ottawa) is mitigating. I assume it is killed to the ground in winter and likely doesn't flower (hence the extra large size of the leaves) and therefore can't spread by seed here. Can't find it again now but I did find a reference to its being killed to the ground in eastern Canada.
