Bistorta polymorpha (syn. Persicaria)
A perennial mainstay in Europe and a key player in the Dutch and German Waves of garden design is this nearly perfect Fleece Flower and for darn good reason. This behaves itself and doesn't run or seed, just clumps and blooms all summer until frost. The white flowers provide critical contrast and a cooling point for the hot colors of the summer border - a visual iceberg for your fevered eye to stretch out belly flat like your hiking dog buddy does on that lingering snowbank high in the mountains in late summer. Very hardy, very easy, this works with nearly everything and will make you look like you have realized your potential.