Habitat
native to Japan
hardy to zone 5
Special Note: This species has demonstrated an invasive tendency in Connecticut, meaning it may escape from cultivation and naturalize in minimally managed areas. For more information, Click Here.
Habit and Form
a climbing deciduous vine
typically reaches heights of 35′, but can grow higher.
a hefty vine that climbs by twining around structures
the vines circle in a clockwise fashion
vines can grow to several inches in diameter
strong, sturdy support structures are needed for this plant due to weight
can be trained into a tree-like form
Summer Foliage
odd, pinnately compound leaves
leaves contain 13 to 19 leaflets
leaflets are 10″ to 15″ long
leaf arrangement is alternate
young leaves are silky pubescent
leaf color is bright green
emerging leaves may be red-tinged
Autumn Foliage
no color change
perhaps a bit of yellow
Flowers
bloom time is mid-may
showy, pendulous clusters of pea-like flowers
flower color is blue-violet to reddish violet
flowers are fragrant
flowers clusters are 8″ to 20″ long
occasionally small flowers are borne later in the season on new growth
Fruit
4″ to 6″ long brown pods
change to brown in October and persist
Bark
old trunks develop picturesque fluted and muscle-like form
bark is gray in color
Culture
full sun
moist, deep, fertile soils are preferred
tolerant of many soils and relatively tough sites
soil pH adaptable, even liking a higher pH
can be difficult to get to bloom
suggested flower inducing treatments include; root pruning, phosphorous fertilizer, and cutting back of shoots to 3 to 4 buds
the best way to insure flowering is to use named cultivars selected for dependable bloom
avoid seedling plants as they will likely be slow to bloom
Landscape Use
specimen
screen (if supported)
over arbors
can be trained into a small free-standing tree (standard)
for dramatic flowering effect
Liabilities
plant often fail to bloom reliably
cold injury to flower buds
a rampant grower that can be hard to contain
needs heavy-duty support structures of pipe of 4X4 wood.
ID Features
a twining vine, climbing by clockwise rotation
easily confused with W. sinensis which has a counterclockwise rotation
flowers open from the base to the apex, unlike W. sisensis where all flowers open more or less simultaneously
spine-like projections at the base of each raised leaf scar
smooth, fluted, muscle-like trunk
Propagation
by cuttings
by seed
by grafting
Cultivars/Varieties
‘Alba’, ‘Ivory Tower’, ‘Longissima Alba’ and ‘Snow Showers’ – These are white-flowered forms with a heavy fragrance. The latter three forms feature flower racemes that may reach 2′ long.
‘Carnea’ (also known as ‘Kuchibeni’) – An unusual plant, this cultivar offers pleasantly fragrant blooms that are colored white with pinkish tips.
‘Issai’ – This cultivar offers violet to bluish-violet flowers in 12″ long racemes.
‘Macrobotrys’ – Notable for its very long racemes of reddish-violet, fragrant flowers, this plant has flower clusters that typically are just under 2′ long (they can be 3′ to 4′ long).
‘Rosea’ – Rose-pink flowers that possess good fragrance grace this vine in spring.
‘White Blue Eye’ (also listed as ‘White/Blue Eye’) – Sometimes offered by specialty nurseries, this novel selection offers white flowers that are marked with a blue-violet blotch.
‘Variegata’ (also known as ‘Mon Nishiki’) – Various variegated clones are known by collectors. Most forms offer foliage splattered with cream or yellow that may fade to green in warm summer areas. The flowers are as per the species.
‘Violacea Plena’ – This selection has violet-blue, double flowers borne in clusters just under 1′ long. They are not especially fragrant.
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