Here I am asking for ID help again - twice in one week! Anyway, I ID'd this plant about 3 weeks ago and promptly forgot about it since it was reported to be highly invasive. Now a fellow gardener has asked about the very same plant. I'll be darn if I can remember what it was, and Google Images is being stubborn about popping up a picture that matches.

Hopefully someone here with a better - or younger - memory can put me out of my search misery.

June