Vines are woody or perennial plants that grow through the elongation of the stem and climb vertically or horizontally, depending on how they are trained. Vines are not strong enough to support their vertical growth without support. Many vines naturally attach to walls and fences with their stems, tendrils, or suction disks or claws, though some need tying in order to attach to their supports. They are invaluable additions to landscapes and are used to decorate walls, cover arbors, and climb fences. In addition to softening hard vertical surfaces and edges, many vines display showy flowers for long periods of time.