Styrax Japonicus

, also known as the Japanese snowbell, is a species of flowering plant in the family Styracaceae, native to Korea, Japan, and Southern China. Growing to tall by broad, it is a graceful, spreading deciduous tree with oval, upward-facing leaves which occasionally turn yellow or orange before falling in autumn. Masses of slightly fragrant, bell-shaped white flowers hang from the branches in summer, followed by fruits (drupes) which resemble olives in both shape and colour.

It is hardy down to , but prefers a sheltered position in full sun or dappled shade, with acidic or neutral soil.

Due to its plentiful flowers, the tree has been widely cultivated in Western gardens. Properties such as analgesic, hypoglycaemic, and antibacterial effects have been observed in extracts and isolates from the flowers, stem-bark, and leaves, respectively.

Etymology

''Styrax japonicus'' is a member of the Styracaceae family, with the authority of Siebold & Zuccarini. ''Styrax'' is a genus whose members produce aromatic resins. The Latin specific epithet ''japonicus'' means “from Japan”.

The Japanese common name, , originates from how the fruit annoys the throat and tongue when put in the mouth — or describes something that evokes a repulsive, bitter flavor.

Description

The appearance of ''Styrax japonicu''s ranges from a large shrub to a small tree.

Leaves

Leaves are simple in alternate arrangement. They are upward-facing with an oblong shape, dark green and shiny.

Flowers

The flowers of ''S. japonicus'' are pendulous and arranged in a raceme inflorescence. When in bloom, they evoke a light fragrance. The petals are commonly colored white; however, the petals of the 'Pink Chime' cultivar is pink. The five-petaled, bell-shaped corolla is around 2-3 cm long and typically blooms in late spring. The corolla is surrounded by 5-toothed calyx. They are perfect and perigynous with prominent yellow stamens.

Fruit

The gray-green drupe-like capsule fruits of ''S. japonicus'' are around long, appearing around August and September. Long stalks extend from each drupe and attach with star-shaped calyx. Each fruit contains one seed.
Styrax japonicum SZ23.png, Plate from ''Flora Japonica'' (1870)
Styrax japonicus 05.JPG, Flowers and buds
Poecile varius eating Styrax japonica.JPG, Varied tit eating the fruits

Distribution and habitat

Distribution

''Styrax japonicus'' is native to Korea, Japan, and Southern China. It has the largest distribution out of the members in the genus '' Styrax.'' An attractive landscape tree, it can be found commonly within parks and gardens.

Habitat

Generally pest-resistant and disease-resistant, weaker trees may be susceptible to the ambrosia beetle. It is cold hardy to , with a classification of USDA hardiness zones ranging from 5-8, depending on the cultivation and provenance.

''S. japonicus'' prefer acidic or neutral soil. They should be planted with full sun or part sun/part shade exposure, protection from cold and dry wind, and provided consistently moist soil.

There is no known threat to the conservation of the species. The IUCN Red List of Threatened Plants ranks ''S. japonicus'' as "Least Concern", last assessed in 2018.

Cultivation

The first introduction of ''Styrax'' to the West was by Richard Oldham in 1862. ''Styrax japonicu''s is known to be one of the most cultivated species in North American and European gardens and one of the most common ''Styrax'' cultivars. It has been cultivated for its pendulous forms, flower color, dwarfism, foliage colorization (such as burgundy leaves), and temperature tolerance.

In particular, the Japanese name Group, refers to cultivars with pink flowers and is inclusive of the cultivar 'Pink Chimes'. Japanese gardeners use the term to describe this cultivar.

The cultivar 'Fargesii', with larger flowers and leaves than the typical species, has gained the Royal Horticultural Society's Award of Garden Merit.

Common Cultivars include:

* 'Angyo Dwarf'
* 'Carillon'
* 'Crystal'
* 'Emerald Pagoda'
* 'Evening Light'
* 'Fargesil'
* 'Fragrant Fountain'
* 'Issai'
* 'Pink Chimes'
* 'Snow Cone'

Medicinal properties and uses

Phytochemical properties

Analgesic effects have been found with the use of flower ethanol extracts, with kaempferol-3-O-rutinoside suggested as the active analgesic component.

Extracts found from the stem-bark have hypoglycaemic effects (in particular, triterpenoids and sterol), as well as isolates that serve as immunity regulators (egonol, masutakeside I, straxosides A, and straxosides B).

It is also suggested that ''Styrax'' ''japonicus'' contains antibacterial properties. Water extract of ''S.'' ''japonicus'' leaves inhibited growth against ''Escherichia coli'', ''Klebsiella pneumoniae'', ''Salmonella'' and ''Staphylococcus aureus'' (except ''Candida albicans''). Steam distillation and solvent extraction of leaves had antibacterial effects on ''Bacillus cereus'' and ''Salmonella Typhimurium''.

Ornamental use

The masses of flowers present on a blooming tree lead to the pronounced prevalence and popularity of ''S. japonicus'' cultivars. It is thought that the tree's abundant flowers, along with its lavish foliage and striated bark, contributed to its successful introduction from Eastern Asia to Western gardens.

However, ''S.'' ''japonicus'' has a relatively limited flowering period; a single flower has a blooming period of 4-5 days before wilting and a group of flowers last around 2 weeks, prompting studies investigating how to prolong the flowering period.

Medicinal use

Chinese traditional medicinal use of ''S.japonicus'' has phamacological evidence, such as the anagesic effects used to treat toothaches and sore throats and antitussive purposes to treat coughs.

Cultural Use

Along with its cultivation for ornamental use, ''S. japonicus'' has been used for its material and chemical contents. The hardwood was used to compose umbrella ribbing and pieces for shogi (a Japanese strategy board game).

The dried pericarp of young fruit has been used to make washing soap, due to saponin contents. It also contains large amounts of egosaponin, a poisonous agent that has been used in East Asian traditional fishing to stun fish and make them easier to catch.

References

japonicus
Flora of China
Flora of Japan
Trees of Korea
Plants described in 1837

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