Wisteria
How do you identify it?
The vines of Japanese wisteria twist around its host plant in a clockwise direction, whereas those of Chinese wisteria are counter-clockwise. Leaves for both species are alternately arranged and compound, and leaflets have wavy edges. Flowers are blue or violet. These two invasive species can be distinguished from the native American wisteria, W. frutescens, by their fuzzy seed pods.
Why is it invasive?
Invasive wisteria species have spread into natural areas from the landscape. The vines can girdle native plants and trees, and shade native species. They may be spotted along roadsides and forest edges, and they can persist in partial shade. They can reproduce through runners.
How can you manage it?
These invasive vines are difficult to control. Mechanical control is only possible for small infestations. Herbicides applied as foliar sprays or using the cut stump method are useful. Glyphosate or triclopyr can be used. See the N.C. Forest Service leaflet for more details on herbicide use, and make sure to follow all label instructions.
Even though this plant’s beautiful spring blooms can be enticing, it is easiest for you and best for the environment not to plant exotic wisteria. There are a variety of creeping or climbing vines native to the eastern United States that are good alternatives to the invasive exotic wisterias. Some examples include trumpet creeper (Campsis radicans), trumpet honeysuckle (Lonicera sempervirens), Dutchman’s pipe (Aristolochia macrophylla), crossvine (Bignonia capreolata) and American wisteria (Wisteria frutescens) although it is often difficult to find.
Invasive Species Leaflet IS-20 Wisteria floribunda and Wisteria sinensis (North Carolina Forest Service)
Climbing wisteria vines have the ability to strangle and kill mature trees, which opens the forest canopy and makes conditions more favorable to their own aggressive growth. Exotic wisteria thrives in full sunlight but can persist and reproduce in partial shade. These vines are commonly seen growing along forest edges and roadsides.
Wisteria (Mississippi State University Extension)
Wisterias can be a problem in fence rows, forests and landscapes. Wisteria forms dense thickets, replacing the surrounding vegetation. Although these thickets may provide habitat for certain wildlife, they are a difficult barrier for human and animal activity.
Non-native Wisterias: Chinese and Japanese (UGA Cooperative Extension)
Its seems that wisteria is everywhere you look–intertwined in trees, in abandoned lots, along fences, in the woods and in some landscapes where it was planted on purpose. While the flowers are beautiful, this plant can have deadly consequences on mature trees.
Weeds Gone Wild: Alien Plant Invaders of Natural Areas (UGA Center for Invasive Species and Ecosystem Health)
Exotic wisterias are long-lived, some vines surviving 50 years or more. Vegetative reproduction is their primary means of
expansion. Numerous 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.