November 28, 2007
Chinese wisteria (Wisteria sinensis) and Japanese wisteria (W. floribunda) are deciduous high climbing, twining, or trailing leguminous woody vines to 70 feet with long pinnately compound leaves and showy spring flowers. Chinese and Japanese wisterias are difficult to distinguish from one another due to possible hybridization.
Ecology. Form dense infestations where previously planted. Occur on wet to dry sites. Colonize by vines twining and covering shrubs and trees and by runners rooting at nodes when vines covered by leaf litter. Seeds water-dispersed along riparian areas. Large seed size a deterrent to animal dispersal.
History and use. Introduced from Asia in the early 1800s. Traditional southern porch vines.
Stem. Woody vines to 10 inches in diameter with infrequent alternate branching.Twigs densely short hairy. Older bark of Chinese wisteria tight and dark gray with light dots (lenticels) compared to white bark of Japanese wisteria.
Leaves. Alternate, odd pinnately compound 4 to 16 inches long, with 7 to 13 leaflets (Chinese) or 13 to 19 leaflets (Japanese), and stalks with swollen bases. Leaflets oval to elliptic with tapering pointed tips 1.6 to 3 inches long and 1 to 1.4 inches wide. Hairless to short hairy at maturity but densely silky hairy when young. Margins entire and wavy. Sessile or short petioled.
Flowers. March to May. Dangling and showy, stalked clusters (racemes) appearing when leaves emerge, 4 to 20 inches long and 3 to 3.5 inches wide. All blooming at about the same time (Chinese) or gradually from base (Japanese). Pealike flowers, corolla lavender to violet (to pink to white). Fragrant.
Fruit and seeds. July to November. Flattened legume pod, irregularly oblong to oblanceolate, 2.5 to 6 inches long and 0.8 to 1.2 inches wide. Velvety hairy, greenish brown to golden, splitting on two sides to release one to eight flat round brown seeds, each 0.5 to 1 inch in diameter.
Resemble native or naturalized American wisteria, W. frutescens (L.) Poir., which does not form extensive infestations, occurs in wet forests, flowers in June to August after leaves developed, and has 6-inch flower clusters, 9 to 15 leaflets, hairless pods, and slender old vines. Also may resemble trumpet creeper, Campsis radicans (L.) Seem. ex Bureau, which has leaflets with coarsely toothed margins.
Recommended control procedures:
Thoroughly wet all leaves (until runoff) with one of the following herbicides in water with a surfactant:
- July to October for successive years when regrowth appears--Tordon K® as a 3-percent solution (12 ounces per 3-gallon mix), Tordon K® as a 2-percent solution (8 ounces per 3-gallon mix), or Garlon 4 as a 4-percent solution (15 ounces per 3-gallon mix)
- July to September for successive years when regrowth appears a Transline® as a 0.5-percent solution in water (2 ounces per 3-gallon mix) when safety to surrounding vegetation is desired
- September to October with repeated applications--a glyphosate herbicide as a 2-percent solution (8 ounces per 3-gallon mix)
From: Miller, James H. 2003. Nonnative invasive plants of southern forests: a field guide for identification and control. Gen. Tech. Rep. SRS-62. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 93 p.
* Nontarget plants may be killed or injured by root uptake.
Transline controls a narrow spectrum of plant species.
When using Tordon herbicides, rainfall must occur within 6 days after application for needed soil activation. Tordon herbicides are Restricted Use Pesticides.