Plant Characteristics
Wisteria is a member of the Pea family, Fabaceae (formerly Leguminoseae). The genus was named in honor of an anatomy professor at the University of Pennsylvania, Caspar Wistar (1761-1818). The genus includes ten species of deciduous climbing vines, two native to the southern United States and the others native to eastern Asia.
Wisteria are vigorous, twining vines with wide landscape usage where space permits and gardeners are committed to keeping them in bounds. Among their attributes are hardiness, vigor, longevity and the ability to climb high. They are greatly valued for their large, pendulous flower clusters that occur in the spring. Flowers are pea-like and may be white, pink, lilac-blue, bluish-purple or purple in color. The fruit is a long, green flattened pod that is not particularly ornamental. The plant climbs by means of twining stems and has alternate, pinnately compound leaves. Older, established plants may have a twisted, woody trunk several inches in diameter. Plants that have been grown from seed remain in a long juvenile stage and often do not bloom for 10 to 15 years or longer. Plants that are grafted, and plants grown from cuttings or layered from a flowering plant will usually begin flowering earlier than seedlings.
Two species of wisteria are typically grown in home gardens: Wisteria sinensis or Chinese wisteria, and Wisteria floribunda or Japanese wisteria. The Chinese wisteria is the more popular plant due to its flowering habit. It grows to a height of 25 feet or more and has flower clusters six inches to a foot in length, which open before the foliage has expanded. Individual flowers in the clusters open all at once for a very showy display. Flowers are violet-blue and slightly fragrant. Plants are most showy from early to mid-May in most seasons. There is also a white flowering form of Chinese wisteria, W. sinensis 'Alba,' which is very fragrant. Two cultivars include: 'Black Dragon,' which has double dark purple flowers and 'Plena' with double, rosette-shaped, lilac flowers. Chinese wisteria may bloom within three to four years after planting; however, the juvenile period may be much longer.