Besides its name - I just love to slip "Cimicifuga" into a conversation anytime i can - this perennial wildflower, native to the Eastern United States, is a lovely architectural specimen most suited to the moist woodland garden or a shaded site.  Cimicifuga grows from four to six feet, with large leaves, many stems, and lovely spires of fragrant white flowers in summer.  Cimicifuga needs consistently moist soil, so don't let it dry out.  Native Americans used the roots and rhizomes for medicinal purposes, and it is still used today.  Zones 4-9.  (Photo by Valerie, from Wiki Commons.