Sweetautumn clematis (Clematis terniflora
). For the better part of the growing season, sweetautumn clematis is a twining vine that's pretty innocuous until late summer and early fall, when the foliage is literally smothered with small white flowers—a welcome feast for the eye as the season winds down. Don't depend on sweetautumn clematis to give you full coverage of a support from the ground up. More often it climbs to the top of its support and then tumbles over and over itself, creating a mound of white at the top. A woody vine that comes back every year, it's a very fast grower (USDA Zones 5 to 8, possible 9).