Gerald L. Klingaman
Plant Common Name
Popular for their showy flowers, plants in the genus Wisteria encompasses approximately 10 species of woody, deciduous vines, which are native to China, Korea, Japan and the eastern United States. The genus was named by the botanist Thomas Nutall in honor of Dr. Caspar Wistar (1761 - 1818), a professor of anatomy at the University of Pennsylvania.
Wisteria vines climb by twining around supports rather than clinging by tendrils or roots. Some species can become very large and damage supporting structures or kill the plants they twine around. Generally, their leaves are compound with many leaflets held on a central supporting leaf stem. Their sweet pea-like flowers are borne in large, pendulous clusters. They are often fragrant and come in shades of lavender, purple, white or pink, depending on the species. The thick, flattened fruits that follow look like large bean pods. These split when mature to expel lots of round, bean-like seeds.
Chinese wisteria (Wisteria sinensis) is arguably the most popular species grown. It is an aggressive but pretty vine that twines in a counter-clockwise direction and offers large, broad panicles of fragrant spring flowers. The equally aggressive but pretty Japanese wisteria (Wisteria floribunda) twines in a clock-wise direction and has very long, fragrant, pendulous, flower clusters. The American wisteria (Wisteria frutescens) is native to the southeastern United States and offers short clusters of lavender-purple blooms in summer.
Culture and hardiness are species dependent. Most can only be grown where winters are cold. Generally, Wisteria requires well-drained soil, steady moisture, and full sun to flower well. Most species are difficult to establish and young plants often need several year’s growth before flowering. Regular pruning is often required to shape and control these aggressive vines. Wisteria tend to topple weak supports so provide them with sturdy anchoring systems. Beware tree climbers as they have the tendency to eventually strangle their supporting plants.
Plant Wisteria for their spectacular blooms. They are beautiful trained as small trees or trailing along strong pergolas, trellises and arbors.
Some species are toxic if ingested. For more information go to: http://www.ces.ncsu.edu/depts/hort/consumer/poison/Wistesp.htm. Likewise, several Wisteria have the tendency to become invasive. For more information about their invasiveness see: http://www.nps.gov/plants/alien/fact/wist1.htm