A lovely, aromatic Wisteria, Wisteria frutescens (American Wisteria) is a strong-growing climber with twining stems of great beauty. It produces masses of large drooping clusters, 6 in. long (15 cm), packed with fragrant, pea-like, lilac-purple flowers tipped. Blooming from the base of each cluster to the tip, they appear in late spring or early summer after the leaves emerge. The flowers are followed by attractive, bean-like pods, 5 in. long (12 cm), which ripen in summer and may persist…