An estate landscaper gave me the plant 2 falls ago; overwintered in my grhouse. Planted again, and it grew all summer. Died off, and didn't return. But all around where it was, bright green plants have come up this summer,and I think it's this. Has a small pretty yellow blossom in late summer/fall, grows to about 18". He said the ancients brewed the leaves into tea to make an aphrodisiac for the ladies.
"Titalaria" or similar name - Ancient love potion