Styphnolobium japonicum - Japanese Pagodatree
Family: Papilionaceae

Hear the scientific name

Styphnolobium japonicum is a large, rounded, shade tree that doubles as an ornamental tree, profusely flowering in Aug. or early Sept. with creamy-yellow large inflorescences. Japanese Pagodatree has many liabilities that limit the planting of this unusual tree in urban landscapes.

Former scientific name: Sophora japonica

F   E   A   T   U   R   E   S
  form Form

-large shade tree, doubling as a large ornamental tree

maturing at about 60' tall x 80' wide, but can get even larger

-upright rounded growth habit in youth, becoming more spreading with age

rapid growth rate in youth and middle age, becoming a medium growth rate with maturity

foliage Foliage

-alternate, medium to dark green, with about 9-13 ovate leaflets (with acute apices) per pinnately compound leaf, having faded green to yellowish green autumn color

-trees will often drop a slow but continuous stream of leaflets, rachises, and entire leaves from mid-summer through early-autumn (before the advent of normal autumn leaf abscission), in response to both abiotic and biotic stresses

-trees cast a light dappled shadein youth, but a much more dense shade with maturity

Flowers
flowers

-creamy-white to yellowish-green large inflorescences blanket the tree anytime from early Aug. to early Sept., with about a 3-week bloom period

-young seedling trees may not flower for the first 10 or so years unless the cultivar 'Regent', which flowers at a young age, is used

Fruit
fruit

-thick green pods mature to yellow-green fruits, with the large beans appearing as knobs within the otherwise thin pods, hanging profusely from the tree

-ripening in Oct.-Nov. and persisting into Dec. or beyond

Twig

-bright green in spring on the emergent stems, becoming kelly green to medium green in summer, and persisting as a dark green during the winter, remaining so for several years afterwards on the young branches, slowly fading to tan on the mature branches

trunk Trunk

-branches are lightly furrowed and yellowish green-brown, but appear as if they are striated (i.e., having light brown, diffuse, straight lines on the lime green bark)

-trunks have interlacing ridges and are more deeply furrowed, becoming light brown to gray-brown with maturity

-wood is relatively weak, and the branches are prone to storm damage (with or without cankers and wood rot) with their increasing age and weight

-growth habit is very rounded, resulting from the loss of the central leader at an early age (for the species form)

C   U   L   T   U   R   E
 

Culture

-full sun to partial sun

-performs best in full sun in moist, well-drained soils of average fertility, but is very urban tolerant (especially to heat, drought, pollution, compacted soils, and poor soils)

-species form is propagated by seed, and cultivars are budded onto seedling understock

-several potential diseases (including branch and trunk canker [which can lead to wood rot and storm damage] and twig blight [which leads to leaf abscission and stem dieback]) and at least one potential pest (potato leaf hopper [which kills the new growth, leading to the resultant regrowth as witches' brooms])

-low availability, in B&B form

Hardiness

-zones 5 to 8

Origin

-native to the Orient

U   S   A   G   E
 

Assets

-showy creamy inflorescences in mid- to late-summer

-rapid growth rate

-urban tolerance

-dappled shade in youth

-wildlife attraction when in fruit

Liabilities

-fruit abscission (and bird deposition of fruit residue) from Oct. through Dec., a true liability if the tree is sited near parking lots, sidewalks, etc.

-continuous sequence of dropping leaflets, rachises, flowers, fruits, and pedicels from July through Dec., and dead stem abscission year round

-weak wood and brittle stems, often resulting in storm damage with age

-potential for numerous diseases and pests

-species form is slow to flower as a young tree in the northern areas of its range

-poor autumn color

-marginally hardy in severe zone 5 winters, exhibiting twig dieback

Function

-shade, specimen, or summer-flowering focal point

Texture

-medium texture in foliage and when bare

-thick density in foliage and when bare

S   E   L   E   C   T   I   0   N   S
 

Varieties and Cultivars - Search OSU PlantFacts for additional plants in this species

Alternates

-medium- or large-sized shade trees with showy flowers in summer (Koelreuteria paniculata, Liriodendron tulipifera, Magnolia grandiflora, etc.)

-urban tolerant shade trees (Acer platanoides, Fraxinus pennsylvanica, Gleditsia triacanthos, Quercus rubra, etc.)

 


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