🔴 Invasive - Remove
Wisteria (Chinese and Japanese)
Wisteria sinensis, W. floribunda
This is an invasive species that harms native ecosystems. It should be removed when found to protect local plant and wildlife habitats.
Description
A heavy woody vine with compound leaves and hanging clusters of fragrant purple flowers in spring. Escaped from gardens it climbs and strangles trees, its stems thickening into trunks that can pull down a canopy.
Where you'll find it
- Around old house sites, cemeteries, park buildings and arbours. Every wild stand started as a planting.
- High in big trees, with stems as thick as an arm spiralling up the trunk.
- Spreading along the ground by runners at the edge of an old patch, far further than anyone planted it.
Background
Native to: China and Japan
Imported in the 1810s and 1830s as an ornamental for porches and arbours. Old plantings around house sites, cemeteries and parks are where most wild stands begin.
Ecological impact
Twines tightly around trunks and girdles trees as it thickens, and its weight breaks limbs. Dense mats shade out everything beneath. It spreads by runners as much as by seed, so a single planted vine becomes an acre.
How to identify
The leaf
- Seven to nineteen leaflets in pairs along one stalk.
Colour and texture: Fresh mid-green; older vines are smooth and grey-barked.
Leaves: alternate, pinnately compound with 7–13 (Chinese) or 13–19 (Japanese) leaflets.
Stems: twine tightly; older vines are smooth, grey, and can be thicker than an arm.
Flowers: long drooping clusters of purple, fragrant flowers in April–May, usually before the leaves are fully out.
Pods: velvety, bean-like, 4–6 inches, persisting into winter.
Seedheads & fruit
Pods August through the winter.
Flat, velvety grey-green bean pods four to six inches long, hanging in bunches, drying brown and splitting open with an audible snap.
Why it matters: Velvet pods say Chinese or Japanese wisteria; our native American wisteria has smooth, hairless ones. A pod-covered vine also tells you the stand is old enough to be girdling trees.
Preferred removal method
Cut a window in the vine
A woody vine climbing a tree. This is the safe way to free a tree: you never pull a vine down out of a canopy.
- 1Cut every strand at ankle height, all the way round the trunk.
- 2Cut again as high as you can comfortably reach. No ladders, no pulling on branches.
- 3Pull out the band between the two cuts so the vine cannot rejoin, and leave everything above it to die in place. It drops on its own over a season.
Avoid: Do not haul the vine down. It is tangled into the branches, and pulling brings down deadwood on top of you.
Wrench the crown out
A woody crown too big to pull and too stubborn to cut: wineberry, multiflora rose, barberry, bush honeysuckle, tree seedlings.
- 1
Disposal
It can stay on site. Cut vine and wrenched crowns can stay. Pile them off the ground; wisteria re-roots from stems left lying on soil.
Don't confuse with a lookalike
Native American Wisteria vs Chinese and Japanese Wisteria
There is a native wisteria, it is planted in gardens too, and it does not strangle trees. The flowers tell you which one you have, and so does the calendar.
American Wisteria
Wisteria frutescens
Native: keepA short, dense cluster, out after the leaves.
