Virgin's Bower is just one of the common names of this beautiful, white-flowering native Clematis.  It is also sometimes called "Old Man's Beard" and "Devil's Darning Needles."  I like them all.  Although all parts of Clematis virginiana are considered toxic, the plant was used at one time by Native Americans as a remedy for backaches, stomach and nerve maladies, and as an hallucinogen.  This member of the Buttercup family grows from 12 to 20 feet and, lacking tendrils, supports itself by its twisted stems that wrap themselves around posts, fences, other plants and trees, and just about anything else that gets in its way.  In late summer/early fall, Clematis virginiana is smothered in clusters of showy, fragrant white flowers and followed by feathery seed pods.  One word of caution:  It is not a vine for small gardens or the faint at heart:  it can be invasive and difficult to eradicate unless you have a plan of action to remove spent flowers before they produce seeds.  A heavy pruning in spring will promote bushiness.   Sun, part shade, full shade.  Zones 4-8.