Perennial Climbing Plant Yellow Thunbergia Alata (Black-eyed Susan Vine) 200 Seeds an ornamental plant in gardens easy to germinate in humus-rich soil with some sand The flowers have five petals and appear throughout the growing season. Thunbergia alata has a vine habit, and can grow to a height of 68 ft (1.8-2.4 m) in tropical zones. fast grower, blooming quickly, with light trimming encouraging more blossoms.