Persicaria Polymorpha - a heroic plant.  Heroic because it does more (as poly indicates) than any normal plant could be expected to do.  It is big, bold and beautiful.  It puts out its big leaves early in spring and achieves a height of six feet.  It produces big, white, showy blooms at the end of June and it holds those blooms into September.  Strong and full, it needs no support and  serves well as a background plant, one large enough to hide a fence and amaze the neighbors.  Check it out next to one of the "antique" outhouses at Monches Farm.  Maybe its name comes from Perseus, the Greek hero who slew dragons and saved maidens.