Wisteria – refers to Caspar Wistar (1761-1818), physician and professor of anatomy at the University of Pennsylvania

• name given by botanist Thomas Nuttall (remember Cornus nuttallii?) to his mentor

Native range: China, Japan & Eastern North America

Leaves:

• alternate
• pinnately compound
• 3–19 leaflets

Flowers:

• legume flower
• large
• scented
• pendulous racemes
• white, purple, pink

Fruit:

• legume
• large velvety pods

Other characteristics:

• woody climber
• deciduous

Relevant info:

• N-fixing
• avoid adding nitrogen in cultivated landscapes
• in gardens, requires regular pruning to limit spread and promote flowering
• W. floribunda (Japanese wisteria)
  • floribundi – free-flowering or producing abundant flowers
  • is on the Graham Visitors Center (of the WA Park Arboretum) arbor
  • twines clockwise
• W. sinensis (Chinese wisteria)
  • also commonly grown in PNW
  • twines counter-clockwise
• hybrid of W. floribunda and W. sinensis is invasive in SE US
  • climbs and twines around other plants, eventually shading and girdling native plants
• W. frutescens is native to the wet forests and streambanks of SE U.S.
• W. macrostachys is native to the low swampy woods and along the borders of swamps, bayous and low streams of south-central U.S.

Ecology & Adaptations:

• at Graham Visitors Center (of WA Park Arboretum):
  • W. floribundi (Japanese wisteria):
    • native to S. Central & S. Japan
    • found widely in deciduous broad-leaved forests in Japan
• species native to China are found in mountain forests and valleys at 500-1800 m elevation
• brought to the U.S. in 1830
• many cultivars
• pollinators – fragrance of nectar (smells like grapes) attracts hummingbirds, butterflies and probably other insects
• vegetative reproduction:
  • produces suckers (new stems) from roots
  • reroots at nodes of aboveground stolons
  • re-sprouts from trunk and root fragments
• shade tolerance – able to adjust to wide range of light conditions (e.g., W. sinensis lowering light saturation point and photosynthesizing efficiently in lower light conditions)
• competition:
  • climbing habit enables plant to reach more sunlight
  • relies on physical support of other plants to grow
  • in late spring, blooms and simultaneously sprouts new lianoid (vine-y) stems (from the older wood) that twine clockwise around the trunks and branches of host trees or shrubs
• adapted to low-nutrient environment:
  • N-fixing bacteria in root nodules convert nitrogen in the air to a form that the plant can use
  • enables the plant to live in low-nutrient environment