Complete List Annual bastard-cabbage Amur corktree Asiatic colubrina Asiatic sand sedge Australian pine Black locust Black swallow-wort Burma reed Bush honeysuckles (exotic) Canada thistle Carrotwood Chinaberry Chinese lespedeza Climbing euonymus Cogon grass Common buckthorn Common mullein Common reed English ivy Eurasian watermilfoil Fire tree Fiveleaf akebia Fountain grass Garlic mustard Goutweed Giant reed Japanese barberry Japanese honeysuckle Japanese knotweed Japanese spiraea Japanese stiltgrass Kudzu Leafy spurge Lesser celandine Melaleuca Mile-a-minute Multiflora rose Musk thistle Oriental bittersweet Pale swallow-wort Paper mulberry Perennial pepperweed Porcelainberry Princess tree Purple loosestrife Russian-olive Salt cedar Siberian elm Silk tree Smooth cordgrass Spotted knapweed Strawberry guava Tall fescue Tree-of-heaven Velvet tree West Indian marsh grass White poplar Wineberry Wisterias (exotic) Yellow Himalayan raspberry Yellow starthistle Aquatics Eurasian watermilfoil Herbaceous Plants Annual bastard-cabbage Asiatic sand sedge Burma reed Canada thistle Cogon grass Chinese lespedeza Common mullein Common reed Eurasian watermilfoil Fountain grass Garlic mustard Goutweed Giant reed Japanese knotweed Japanese stiltgrass Leafy spurge Lesser celandine Musk thistle Perennial pepperweed Purple loosestrife Smooth cordgrass Spotted knapweed Tall fescue West Indian marsh grass Yellow starthistle Shrubs Asiatic colubrina Bush honeysuckles (exotic) Common buckthorn Fire tree Japanese barberry Japanese spiraea Multiflora rose Russian-olive Silk tree Strawberry guava Wineberry Yellow Himalayan raspberry Trees Amur corktree Australian pine Black locust Carrotwood Chinaberry Common buckthorn Melaleuca Paper mulberry Princess tree Salt cedar Siberian elm Silk tree Strawberry guava Tree-of-heaven Velvet tree White poplar Vines Black swallow-wort Climbing euonymus English ivy Fiveleaf akebia Japanese honeysuckle Kudzu Mile-a-minute Oriental bittersweet Pale swallow-wort Porcelainberry Wisterias (exotic)

Chinese Wisteria Wisteria sinensis (Sims) DC.
Japanese Wisteria Wisteria floribunda (Willd.) DC.
Pea family (Fabaceae)
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NATIVE RANGE
China and Japan

DESCRIPTION
Chinese and Japanese wisteria are exotic, showy, woody ornamental vines.  These vigorous vines can climb trees, apparently limited only by the height of the tree, and have been observed to reach 65 feet.  Unlike American wisteria (Wisteria frutescens), native to the southeastern U.S., which flowers June through August, and produces a non-hairy seed pod 2-4 inches long, both exotic wisterias flower in the springtime (April-May) and produce a velvety seed pod.  The fuzzy brown seed pods are 4-6 inches long, narrowed toward the base, with constrictions between the seeds.  Stems of the exotic wisterias can grow to 15 inches in diameter in older plants. White-barked Japanese wisteria vines twine clockwise around the host plant and Chinese wisteria twines counter-clockwise. The compound leaves,  consisting of 7-13 (Chinese) or 13-19 (Japanese) smaller leaf units, called leaflets, are about 1 foot long and alternate along the stem.  Fragrant, violet to blue-violet flowers, ½ to 1 inch long, occur in showy, pendulous clusters that hang gracefully from the twining stems.

ECOLOGICAL THREAT
Exotic wisterias impair and overtake native shrubs and trees through strangling or shading.  Climbing wisteria vines can kill sizable trees, opening the forest canopy and increasing sunlight to the forest floor, which in turn favors its aggressive growth.  Chinese and Japanese wisterias are hardy and aggressive, capable of forming thickets so dense that little else grows. 

DISTRIBUTION IN THE UNITED STATES
Japanese and Chinese wisteria are found extensively throughout the eastern states.

HABITAT IN THE UNITED STATES
The ideal habitat for exotic wisterias is in full sun, but established vines will persist and reproduce in partial shade.  Vines often climb surrounding vegetation and structures toward sunlight.  Wisteria tolerates a variety of soil and moisture regimes but prefers loamy, deep, well drained soils.  Infestations are commonly found along forest edges, roadsides, ditches, and rights-of-way.

BACKGROUND
Chinese wisteria was brought to the U.S. from China in 1816 and Japanese wisteria was introduced from Japan around 1830.  Both were brought in as ornamentals.  They have been grown extensively in the southern U.S. as decorative additions to porches, gazebos, walls, and gardens.  Most infestations in natural areas are a result of escapes from landscape plantings. 

BIOLOGY & SPREAD
Exotic wisterias are long-lived, some vines surviving 50 years or more.  Vegetative reproduction is their primary means of expansion.  Numerous stolons, or above-ground stems, develop roots and shoots at short intervals.  Abundant seeds may also be produced if conditions are favorable, but flower buds are susceptible to winter kill.  In riparian habitats, seeds may be carried downstream in water for great distances.

MANAGEMENT OPTIONS
The only practical methods currently available for control of exotic wisterias are mechanical and chemical.  Cut climbing or trailing vines as close to the root collar as possible.  This technique, while labor intensive, is feasible for small populations, as a pretreatment for large impenetrable infestations, or for areas where herbicide use is not desirable.  Wisteria will continue to resprout after cutting until its root stores are exhausted.  For this reason, cutting should begin early in the growing season and, if possible, sprouts cut every few weeks until autumn.  Cutting will stop the growth of existing vines and and prevent seed production.  However, cut vines left coiled around trunks may eventually girdle trees and shrubs as they continue to grow and increase in girth.  For this reason, the vines should be removed entirely or at least cut periodically along their length. 

Manual
Grubbing, removal of entire plants from the roots up, is appropriate for small initial populations or environmentally sensitive areas where herbicides cannot be used. Using a pulaski, weed wrench or similar digging tool, remove the entire plant, including all roots and runners. Juvenile plants can be hand pulled depending on soil conditions and root development.  Any portions of the root system not removed may resprout. All plant parts (including mature fruit) should be bagged and disposed of in a trash dumpster to prevent reestablishment. 

Chemical

Cut stump application
Cut stump treatment, using a systemic herbicide, is effective in areas where vines are established within or around desirable native plants or where they have grown into the canopy. This treatment is effective as long as the ground is not frozen. Cut the stem as close to ground level as possible.  Immediately apply a 25% solution of glyphosate (e.g., Roundup®) or triclopyr (e.g., Garlon) and water to the cross section of the stem.  Retreatment with a foliar application of glyphosate may be necessary for any sprouts.

Foliar application
Use foliar spray herbicide treatments to control large infestations of exotic wisterias. It may be necessary to precede foliar applications with stump treatments to reduce the risk of damaging non-target species.  Apply a 2% concentration of glyphosate (e.g. Roundup®) or triclopyr (e.g. Garlon) and water, plus a 0.5% non-ionic surfactant to thoroughly wet all foliage. Chlorpyralid (e.g. Transline) is effective at a concentration of 0.5% and is selective to plants in the aster, buckwheat, and pea families. Caution should be taken with chlorpyralid as groundwater pollution through leaching can be a problem with certain soil types. Do not apply spray so heavily that herbicide drips off the leaves. Glyphosate is a non-selective systemic herbicide that may kill non-target plants that are only partially contacted by spray. Triclopyr is selective to broadleaved species and is a better choice if native grasses are present. Ambient air temperature should be above 65ºF for all foliar treatments.

USE PESTICIDES WISELY: ALWAYS READ THE ENTIRE PESTICIDE LABEL CAREFULLY, FOLLOW ALL MIXING AND APPLICATION INSTRUCTIONS AND WEAR ALL RECOMMENDED PERSONAL PROTECTIVE GEAR AND CLOTHING. CONTACT YOUR STATE DEPARTMENT OF AGRICULTURE FOR ANY ADDITIONAL PESTICIDE USE REQUIREMENTS, RESTRICTIONS OR RECOMMENDATIONS. 

NOTICE: MENTION OF PESTICIDE PRODUCTS ON THIS WEB SITE DOES NOT CONSTITUTE ENDORSEMENT OF ANY MATERIAL.

CONTACTS
For more information on the management of exotic wisterias, please contact:

• Kris Johnson, Great Smoky Mountains National Park, Gatlinburg, TN

SUGGESTED ALTERNATIVE PLANTS
There are a variety of creeping or climbing vines native to the eastern U.S. that are good alternatives to the invasive exotic wisterias.  Some examples include American wisteria (Wisteria frutescens), trumpet creeper (Campsis radicans), trumpet honeysuckle (Lonicera sempervirens), Dutchman’s pipe (Aristolochia macrophylla), and crossvine (Bignonia capreolata).  Contact your local native plant society for information on sources of these and other native plants.

OTHER LINKS

• Photos at invasive.org

AUTHOR
Tom Remaley, Great Smoky Mountains National Park, Gatlinburg, TN

EDITOR
Jil M. Swearingen, National Park Service, Washington, DC
NCR-EPMT, National Park Service, Washington, DC

PHOTOGRAPHS
Susan Ross, Great Smoky Mountains National Park, Gatlinburg, TN

REFERENCES
Dirr, Michael A.  1990.  Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture, Propagation and Uses.  Stipes Publishing Co., Champaign, IL. Pp. 926-929.

Gleason, H.A., A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. 2nd ed. The New York Botanical Garden, 910.

Isely, D. 1990. Vascular flora of the southeastern United States. Volume 3, Part 2 Leguminosae. Chapel Hill, NC: The University of North Carolina Press, 96.

Radford, A.E., H.E. Ahles, C.R. Bell. 1968. Manual of vascular flora of the Carolinas. Chapel Hill, NC: The University of North Carolina Press, p. 1183.

Rehder, A. 1993. Manual of cultivated trees and shrubs. Vol. 1. Dioscorides Press, Portland OR. p.507.

Thomas, L.K. Jr. 1993. Chemical grubbing for control of exotic wisteria. Castanea, 58(3):209-213.