Gentiana scabra Seeds | Long Dan Cao
LATIN NAME: Gentiana scabra
COMMON NAME: Long Dan Cao, Japanese Gentian, Rough Gentian
Plant Profile
Long Dan Cao is a clump-forming perennial, 30-60 cm tall, with glossy, lance-shaped leaves and trumpet flowers of deep blue in September and October. The flowers open at the top of the stem and are among the last blues of the season.
The root is the medicinal part: long, fibrous and intensely bitter, and it is lifted in autumn from plants three or four years old. The bitterness is so pronounced that the herb is used as a bittering agent in its own right, and a single root will flavour a litre of water.
Gentiana scabra comes from Japan, Korea and eastern China, where it grows in moist grassland and at woodland edges. That origin explains its requirements: an acid soil, steady moisture, and a sunny position with cool roots.
Science & Biotechnology
The bitterness comes from secoiridoid glycosides, chiefly gentiopicroside and swertiamarin, which are among the most bitter compounds known. They stimulate the bitter receptors in the mouth and trigger a reflex increase in digestive secretion, which is the basis of the plant’s use as a digestive tonic.
Gentian roots also contain xanthones, and extracts have shown anti-inflammatory and hepatoprotective activity in animal studies. The clinical evidence in humans is thin, and the herb is used in formulas rather than alone.
The genus is a classic example of alpine adaptation: many species grow at altitude, flower late, and depend on bumblebees for pollination because few other insects are active at that season. Gentiana scabra is one of the easier species to grow, which is why it appears in gardens as well as in medicine.
Uses & Benefits
The root is used in Chinese medicine, usually in combination with other herbs, for conditions described as damp heat in the liver and gallbladder. It is also used in European herbal practice as a bitter tonic, often in small doses before meals.
In the garden the plant is grown for its late blue flowers, which are useful when little else is in bloom. It suits a damp border, a bog garden edge or a woodland clearing. In the trade, the root goes to the herb market and the seed is sold separately to growers who want to raise their own stock.
Growing from Seed
Sow in autumn or stratify for six to eight weeks at 3-5°C, then surface sow at 15-18°C; the seed needs light. Germination is slow and uneven, often six to ten weeks. Fresh seed gives far better results than stored seed.
Plant out at 25 cm apart in light shade or sun with cool roots, in acid soil that holds moisture. Mulch with leaf mould to keep the roots cool, and water in dry spells. The plant resents being moved, so choose the site carefully. Lift roots in autumn of the third year, wash them and dry them quickly in a warm, airy place.
Our Take
A bitter herb and a late blue flower at once, best grown in the damp acid corner where little else will settle.
Related Reading
Readers interested in Long Dan Cao frequently explore these as well: