Wisteria

Wisteria — Wisteria is a genus of about ten species of woody climbing vines native to the eastern United States and the East Asian states of China, Korea, and Japan. Aquarists refer to the species Hygrophila difformis, in the genus Hygrophila, as Water Wisteria.

Wisteria vines climb by twining their stems either clockwise or counter-clockwise round any available support. They can climb as high as 20 m above ground and spread out 10 m laterally.

The leaves are alternate, 15 to 35 cm long, pinnate, with 9 to 19 leaflets. The flowers are produced in pendulous racemes 10 to 80 cm long, similar to those of the genus Laburnum, but are purple, violet, pink or white, not yellow. Flowering is in the spring (just before or as the leaves open) in some Asian species, and in mid to late summer in the American species and W. japonica. The flowers of some species are fragrant, most notably Chinese Wisteria. The seeds are produced in pods similar to those of laburnum, and, like that genus, are poisonous.

The genus was named after Daniel Wister who helped underwrite the voyage of the American commercial vessel Empress of China. The spelling Wisteria is conserved under the International Code of Botanical Nomenclature.

Wisteria species are used as food plants by the larvae of some Lepidoptera species including brown-tail. It is also an extremely popular ornamental in China and Japan.

Wisteria can grow into a mound when unsupported, but is at its best when allowed to clamber up a tree, pergola, wall, or other supporting structure. Whatever the case, the support must be very sturdy, because old wisteria can grow into immensely strong and heavy wrist-thick trunks and stems. These will certainly rend latticework, crush thin wooden posts, and can even strangle large trees. Its pendulous racemes are best viewed from below.