On Corydalis lutea--a very nice plant. It survives the harsh winters of Indiana. It does self-sow , but it is not invasive. Someone mentioned the goose-neck loosetrife=Lysimachia clethroides--it is sensational. BUT this one should be planted in an area where nothing but it is grown. I made the mistake of planting it in a bed primarily devoted to astilbes and hostas and I still cannot get rid of it! Clyde Crockett z5