Swertia japonica

Swertia japonica is a small herb in the gentian family. The family's name is Gentianaceae. The plant is native to South Korea and Japan. Records from Japan list Hokkaido, Honshu, Shikoku and Kyushu. They also list the Ryukyu Islands. It grows in temperate regions, where the climate is mild. It lives on sunny slopes and among thickets. These sites span Japan's lowlands and hills. The RHS lists it as non-native to Britain and Ireland.

Plants reach about 0.7 feet [0.2 metres] tall. The sources give no size for their full spread. Kew lists the plant as annual or biennial. These terms mean a one-year or two-year life span. Plants For A Future gives a wider range. It says plants may live one to three years. They bloom once, then die; this life cycle is called monocarpic. A plant thus does not return once it has bloomed. The flowers have both male and female organs. The evidence gives no flower colour or bloom season. It gives no details of fruit, stems or leaf shape.

Plants For A Future lists light shade as suitable. It names woodland gardens, shaded edges and bog gardens as sites. Its species entry says the plant prefers moist or wet soil. It lists sand, loam and clay as suitable soil types. The stated pH range runs from mildly acid to mildly alkaline. These notes suggest a choice of garden sites and soils. They do not point to one narrow soil choice. The same source says the plant needs help from soil bacteria. It reports little direct knowledge of how this species grows in gardens. How well it withstands British cold remains unclear. The source gives no firm hardiness zone. Some further growing notes cover the genus, not this species.

Records describe the plant's use as a medicinal herb. Plants For A Future says people grow it for this in China. The whole plant tastes bitter. Past uses aimed to boost appetite and ease gut complaints. Such records do not prove that a treatment works or is safe. The source suggests cooked leaves might serve as a vegetable. This food use remains unsure, not a clear recommendation. It lists no known hazards, but this does not prove safety. It reports no other uses and flags no weed potential. The evidence names no pests or diseases.