Japanese Wisteria Hybrid Foliage Showing Compound Leaves and Smooth, Gray Stem
There are two species of wisteria escaped in the eastern United States: Chinese wisteria [Wisteria sinensis
(Sims) DC.] and Japanese wisteria [Wisteria floribunda
(Willd.) DC.]. According to a recent DNA study, these two species have produced many fertile hybrids (Wisteria x formosa
Rehd.) throughout the southeastern United States. Therefore, differentiation between the three can be difficult. Both species are perennial, deciduous vines native to Asia and introduced in the early 1800ís. Chinese wisteria is native to China, while Japanese wisteria is native to Japan. Both species, including the hybrids, have been extensively used as ornamentals. For example, a Chinese wisteria in Sierra Madre, California, planted in 1892, is reportedly the largest blossoming plant in cultivation and produces around 1.5 million inflorescences each year. Once established, wisteria can be difficult to eradicate and can persist for years strangling native trees and shrubs trying to colonize the site. They can also kill, or disfigure, desirable trees in the landscape. In addition, Wisteria leaves, fruit, and seed are toxic. Since characteristics and controls are similar, the same information is provided in IPAMS for Chinese, Japanese and hybrid wisteria.
Wisteria species and hybrids are not regulated in the United States or the MidSouth. They are widely cultivated in the MidSouth as ornamentals.
Chinese and Japanese wisterias have some distinguishing vegetative differences including stems and leaves. Chinese wisteria twines counterclockwise while Japanese wisteria twines clockwise. Leaflets on Chinese wisteria range from 7 to 13, usually 11, while leaflets on Japanese wisteria range from 13 to 19. However with some overlap in leaflet characteristics and the presence of hybrids (Wisteria x formosa
Rehd.), positive identification can be difficult. In general, all wisterias have pinnately-compound leaves that are alternate in arrangement. Leaflets tend to elliptic to ovate in shape and 1 to 4 inches in length. Unlike American wisteria, which reaches 15 to 25 feet, Chinese and Japanese wisterias are high climbing vines reaching upwards of 70 to 80 feet. The record Chinese wisteria in Sierra Madre, California was recorded with a stem length of over 450 feet. Chinese and Japanese wisterias are usually only limited by the structure on which they grow. Wisteria stems (vines) can wrap around structures very tight, slowly killing trees. Stems are relatively smooth and have a light brown or tan coloration. Both vertical and lateral stems are produced. Lateral stems trail across the ground, rooting along its length, and usually tightening with age. Removal of either type of stem can be difficult.
Japanese wisteria Hybrid Showing Pubescent Fruit
Wisteria flowers are born in drooping inflorescences (racemes). Chinese and Japanese wisterias flower earlier than American wisteria. All flowers within an inflorescence open at the same time with little fragrance on Chinese wisteria, unlike Japanese wisteria in which flowers within an inflorescence open from the base to the apex and with stronger fragrance. American wisteria is also fragrant. Flowers have a wide range of colors in cultivation, although escaped forms tend to be some shade of purple with Japanese wisteria flowers typically lighter in color compared to Chinese wisteria. White flowering forms have also escaped. Flowers are 0.5 to 1 inch long and born in long racemes, 4 to 6 inches on American wisteria, 6 to 12 inches on Chinese wisteria, and 8 to 20 inches on Japanese wisteria. Fruit type is a legume, 4 to 6 inches long, and covered with short hairs (velvety) on Chinese and Japanese wisterias. Fruit on American wisteria ranges from 2 to 4 inches long and smooth. The one to three seeds per fruit are flattened and brown.
Wisteria if dispersed vegetatively by stem growth or sexually by seed. However, fruit are poisonous and most likely not dispersed frequently by wildlife. Their use for ornament has most likely lead to invasions in most areas of the United States.
Wisteria is spread primarily by human activity, such as landscape planting, and vegetative growth of vines.
Wisterias can be a problem in fence rows, forest, and landscapes. It can form dense thickets, replacing the surrounding native vegetation. Although these thickets may provide habitat for certain wildlife, they are a difficult barrier for human and animal activity.
Chinese and Japanese wisterias are reportedly widespread in the eastern United States, but the presence of fertile hybrids may compromise current species distributions. American wisteria has a similar distribution in the United States ranging from Massachusetts to Michigan south to Florida and Texas. All are cultivated, especially Chinese and Japanese wisterias and their hybrids. Thus, they are often found in south around old home sites.
Wisterias are widespread in the MidSouth. Introduced species and hybrids are typically associated with old home sites, but can be problematic in newer landscapes if not maintained properly. American wisteria is generally not as aggressive and occurs in and around wetlands.
No biological controls are currently being utilized for wisteria control.
More research is needed on wisteria control, since there are no label recommendations.
Mechanical controls can be used for wisteria control, but tend to be expensive and labor intensive. Lateral stems (vines) are produced at the base of climbing stems and can run a good distance from the original plant. Climbing vines can twine tightly around trees and shrubs making removal difficult. Young shoots can be snapped to prune, but older vines are difficult to cut. In addition, seed may remain in the soil and germinate long after plants are removed. Thus, removal prior to seed production is recommended
No physical controls are widely utilized for wisteria control. Wisteria grows in both shade and full sun habitats.
Dirr, Michael A. 1998. Manual of woody landscape plants: Their identification, ornamental characteristics, culture, propagation, and uses, 5th ed. Stipes Publishing LLC., Champaign, IL.
Mabberley, D.J. 1997. The plant-book: A portable dictionary of the vascular plants. 2nd ed. Cambridge
University Press, NY.
Miller, James H. 2003. Nonnative invasive plants of southern forests: A field guide for identification and control. Southern Research Station, Asheville, NC.
USDA, NRCS. 2007. The PLANTS Database (http://plants.usda.gov
, 6 August 2007). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
The Genus Wisteria
Nutt. belongs to the Legume (Fabaceae) Family. Wisteria
is native to the midsouth, but some species are not. There are six species worldwide occurring in East Asia and North America. American wisteria [Wisteria frutescens
(L.) Poir.][Syn. Wisteria macrostachya
(Torr. & Gray) Nutt. ex B.L. Robins. & Fern.] is native to the eastern United States. It flowers from June to August after the leaves are formed, unlike Chinese and Japanese wisteria which flower April to May. All wisterias generally have flowers some shade of purple, although numerous color forms have been selected including white to bluish and reddish violet. Cultivars with variegated leaves also exist. In 1998, Dirr listed 25 cultivars of Japanese wisteria and possibly 18 cultivars of Chinese wisteria. Dirr also mentions a third exotic species, silky wisteria (Wisteria venusta
Rehd. & Wils.), which has pubescent young stems. It has apparently not escaped in the United States.
Dr. Victor Maddox
Dr. John D. Byrd, Jr., Plant and Soil Sciences, Mississippi State University
Dr. Randy Westbrooks, USGS, Biological Resources Discipline, Whiteville, NC.
Mississippi State University
Geosystems Research Institute
Mississippi State, MS 39762-9555