Lysimachia clethroides is known by the interesting common name of Gooseneck Loosestrife.  A native to China, Korea and Japan, it grows to 3 feet high, quickly spreading as wide or wider.  Erect steams are clothed with pointed olive green leaves.  Flower spikes are densely packed with tiny white blooms 6-8 inches long, arched like a goose’s neck.  Long lasting as a cut flower.  Although it requires vigilance to keep it in check, it’s a nice addition to semi-shady gardens.