The Japanese pagoda tree (Styphnalobium japonicum), also called Scholar tree, is native to China and Korea and not Japan. The first specimens seen in the West came from Japanese sources in the 1750’s, hence its classification as a Japanese tree. The Japanese Pagoda tree is a medium to large size deciduous tree with a broad rounded crown. The compound leaves are alternate, pinnate leaflets. The very showy, greenish-white to yellow flowers are produced in mid to late summer and provide an airy feel to the tree for several weeks. They then give way to seed pod looking like string beans. Tapered greenish-yellow twigs and persistent seed pods in winter is distinctive. The peas are toxic and should not be consumed. The tree turns a brilliant yellow color in the fall. It is a popular ornamental tree in Europe and America. Despite its name the tree is native to China but has been cultivated in Japan for centuries, particularly in temples in and around Kyoto. As Buddhism spread into China, the tree was used as a grave-marker for Buddhist monks. It was introduced to France in 1747 and soon spread to all botanic gardens of Europe. A favorite place for growth has been in universities and other places of learning giving its common name.
The genus name comes from the Greek, styphno “sour” or “astrigent” and lobion “pod” relating to the fresh pod’s pulp taste. The specific name means “of Japan” though the tree is not native to that country. The old name Sophora japonica is still use by some naturalists.
Common name: Chinese Scholar Tree, Japanese Pagoda Tree, Sophora Japonica
Scientific Name (family and order): Styphnolobium japonicum (L.) Schott (or syn. Sophora japanica L.) (Fabaceae, Fabales)
Species Origin: Northern China, Korea
New Jersey Status: USDA Unreported
Habit: up to 100 feet high and 70 feet wide. Bole diameter 1 – 2’. Broadly rounded crown on maturity. Habitat: Zones 4 – 7. Woods, thickets, dry valleys in mountainous regions.
Trunk/Stem: Bark light gray, smooth, develops regular vertical fissures on maturity; bark reminiscent of common ash (F. excelsior ). Glabrous green shoots 1 – 5 year wood; lenticels, nodes protruding.
Leaves: Deciduous, Pinnately Compound, Alternate. Each leaf has 9 – 17 opposite leaflets. Leaflets ovate up to 2” long with tapering narrow tip. Margins entire. Glossy blue-green adaxial; hairy abaxial. The petiole base is swollen (pulvinus) which encloses the bud. Autumn color yellow.
Flowers: Perfect. Pea-like; 5/8” long, white petals (5), fragrant, form on terminal buds; pendulous panicles up to 10” long forming at the end of shoots, in late summer to early autumn. When grown from seeds, the tree may take up to thirty years to produce flowers. The tree flowers best in a hot dry season.
Fruits and seeds: Fruit is a pod, green ripening to brown; it contains up to 6 seeds. After pods abscise the infructescence remains. The seed pods are characteristic with deep bead-like constrictions between the seeds.