Quart Plant from Thunbergia Gandiflora Alba vine. Sometimes called Bengal clock vine, this white variety is very hard to find. Starting in the spring and continuing throughout the summer, this evergreen vine is covered with 4 inch wide soft white flowers that are cuplike funnels with either pale yellow or cream stripes down the center. This fast growing vine can reach up to 20 feet in a season. Hardy in zones 8a to 11, and is root hardy to 20 degrees. Requirements are sun to part shade and does not like to have its roots standing in water. The soft leaves are a medium green of about 8 inches with toothed edges.