Serissa is a monotypic genus of flowering shrubs in the family Rubiaceae (order Gentianales), containing a single species, Serissa japonica. Native to open sub-tropical woodlands and wet meadows across a broad arc of Southeast and East Asia — from India through southern China to Japan — the genus is best known in horticulture under the common names snowrose and tree of a thousand stars.
Serissa japonica is an evergreen or semi-evergreen shrub typically reaching 45–60 cm in height. Its upright stems branch freely in all directions, forming a wide, dense, bushy dome that makes it popular as a bonsai subject and container plant. The leaves are oval, deep green, and relatively thick; when bruised they release an unpleasant odour, which accounts for the historical synonym Serissa foetida. The rough, grey trunk lightens with age, adding ornamental character appreciated in bonsai culture.
Flowers are small, funnel-shaped, and 4- to 6-lobed, measuring about 1 cm across. They open from pink buds into a profusion of white blooms and appear nearly year-round, with peak flowering from early spring through to near autumn. This exceptionally long flowering season, combined with the plant's compact habit, has made Serissa japonica a staple of indoor and outdoor ornamental horticulture across temperate regions worldwide.
Etymology
The genus name Serissa derives from an Indian vernacular name for the plant. One of its best-known synonyms, Serissa foetida, comes from the Latin foetida (stinking), a reference to the unpleasant odour released by the leaves when bruised. Common names in English include snowrose, tree of a thousand stars, and Japanese boxthorn.
Distribution
Serissa japonica is native to open sub-tropical woodlands and wet meadows across a broad range in South and East Asia, extending from India through southern China to Japan. In cultivation it is grown worldwide as an ornamental shrub and bonsai subject in temperate climates.
Cultivation
Serissa japonica is widely cultivated as a bonsai specimen and container plant, prized for its neat bushy habit, fissured grey trunk, and long flowering season. It flowers nearly year-round, with peak bloom from early spring to near autumn; fertilising during this extended flowering period is particularly important. Two cultivar groups — snowrose (smaller flowers) and tree of a thousand stars (differing flower size and shape) — are distinguished primarily by floral characteristics.
