Eclipta

Eclipta prostrata

Wedelolactone · a paddy-bank herb whose sap turns black

Eclipta is an annual of the daisy family, common wherever the ground stays damp — paddy banks, ditch edges, the margins of standing water. Through summer a small white flower head rises singly from each leaf axil. Break a stem or a leaf and the sap that runs out darkens to black within moments in the air, and that property is why the plant was long used to make a black dye. The Donguibogam lists it in the Herb section as 鱧腸, identifies it with 蓮子草, and notes that in common speech it was called 旱蓮子. The original text preserves both the description — the fruit like a small lotus pod — and the observation that sap from a picked shoot blackens in an instant. A Korean name one syllable away, hallyeon, belongs to a South American plant altogether, so it is worth checking which one a seed packet or a dried herb actually is. Modern compositional work reports wedelolactone and related coumestans in the plant. Since paddy banks are exactly where it grows best, avoiding ground that herbicide and pesticide reach comes before anything else.

Year-Round Calendar

Sowing

Harvest

Where It Grows

Wild population Latitudes at 20–30℃ Zoom and pan to explore · temperatures are rough zonal averages

Wild population Common on paddy banks and along waterways in Central and South China; the cut, dried plants are sold in markets.
Wild population Common in paddies and along waterways throughout the country, and the dried herb is traded.
Wild population Grows on paddy banks and along ditches nationwide. Harvest July, August, September
7. 7
8. 8
9. 9

Because it grows along waterways all over the world, from the tropics to the temperate zone, its origin is hard to pin down to a single place, though some consider it native to the American tropics. It is not a crop raised in fields — plants that have come up on their own are cut for use — so there are no country-by-country production statistics, and the list above is not a ranking but a collection of places where harvesting and trade actually go on.

Optimum: 20~30℃
Range: 15~35℃
Hardiness: Not hardy

An annual herb, it grows on paddy banks and ditch edges where the ground never dries out. It tolerates heat and humidity well, but the moment the soil dries its leaves droop, and the first frost ends it for the year — it returns the following year from dropped seed.

In Korea Nationwide

Common nationwide on paddy banks, along ditches, and at the edges of standing pools. Around the time its white flowers bloom, from July to September, it is cut back, leaving the base of the plant.

How to grow

Light: A bright position. It grows in part shade too, but sets fewer flowers
Soil and depth: Soil that never dries out. It wants paddy-bank damp, so in a pot leave a little water standing in the saucer
Spacing: 20cm between plants. It branches sideways and spreads low
Watering: Water before the surface dries. It likes wet feet, and the leaves droop the moment it runs dry
Feeding: It asks for very little. A little compost mixed in at planting is enough
Harvest: Cut in July to September as the white flowers open, leaving the base. The Donguibogam gives the third and eighth months of the lunar calendar. Shake off the soil, wash, drain and dry

What makes the difference. The sap from a cut stem stains fingers and clothes black, so wear gloves. Direct sun bleaches the colour, so hang it in moving air out of the light, and seal it in a container somewhere cool once it is fully dry

Why this one is harder. It is an annual, but it self-seeds so freely that seedlings come up all over the pots the following year. To keep it in bounds, cut the flower stalks before the seed sets

Common problems

Aphids You will see Colonies on the tips of new shoots, turning sticky What to do Wash them off with a jet of water. Since the whole plant is what gets harvested, keep sprays off it as far as possible
Powdery mildew You will see White patches on the leaves as though dusted with flour What to do Open the spacing so air moves through, and remove affected leaves. Do not water over the top of the plant

This page describes how a crop is grown and used. It does not claim health effects for any food, nor is it intended to prevent or treat disease. Component and study notes are references only and do not mean the same result occurs in people. Consult a medical professional about health concerns.

Health Benefits

The old record — yejang (鱧腸). The Donguibogam lists it in the Herb section as 鱧腸, identifies it with 蓮子草, and records that common speech called it 旱蓮子. It sets down a neutral nature, a sweet and sour taste, and no toxicity. On provenance it says the plant is found everywhere, and it is dug in the third and eighth months of the lunar calendar and dried in the shade. It also records the appearance — a fruit like a small lotus pod — and the observation that sap from a picked shoot blackens in an instant. This is a historical medical record and differs from modern judgment.

Analyses of wedelolactone. Repeated analyses report the isolation of wedelolactone and demethylwedelolactone from the whole plant. They belong to the coumestans and are treated as markers of the plant's composition. This is an analysis of composition and has nothing to do with preventing or treating disease.

Nutrition

Wedelolactone (reported in the whole plant) — one of the coumestan compounds
Demethylwedelolactone (found alongside wedelolactone) — a related compound of the same class
Saponins (distributed through the plant) — triterpene glycosides reported in the genus Eclipta

Why the sap blackens Sap from a broken shoot or stem turns black in the air within moments. It is the observation the Donguibogam set down verbatim, and it still happens today on a fingertip or a white cloth. The change is understood as oxidation of the compounds where the cut exposes them to air. This property is what made the plant a source of black dye.

Wedelolactone Repeated analyses report the isolation of wedelolactone and demethylwedelolactone from the whole plant. They belong to the class of compounds called coumestans. This entry stays with the compositional record.

Drying and brewing Cut the whole plant at flowering, dry it in the shade, then chop it small and simmer it in water. Direct sun bleaches the colour, so hang it where air moves but light does not fall on it. Once fully dry, seal it in a container somewhere cool. The brew comes out dark and strongly green-tasting, so start weak.

Pairings

○ Jujube and licorice — The grassy note is strong enough to make a plain brew hard going. Two jujubes or a slice of licorice bring in enough sweetness to carry it. Drop the heat once the pot comes to the boil. Jujube · Licorice

○ A dry pan — Toasting the dried herb briefly in a dry pan cuts the grassy note and brings out a roasted one. Burnt, it turns bitter and nothing else, so stop as soon as the colour deepens slightly.

○ Black dyeing — The blackening of the fresh sap is put to use in natural dyeing. Pound freshly cut stems and leaves, press out the juice, and rub it into cloth to set the colour. The culinary use and the dyeing use come from the same property.

△ Gathering on paddy banks and ditches — The paddy banks and ditch edges where eclipta grows thickest are exactly where herbicide and pesticide land. Do not gather on someone else's field margin, and steer clear of ground that has been sprayed. Anything taken from beside standing water gets several rinses under running water.

△ Telling it from hallyeon — Hallyeoncho and hallyeon are one syllable apart in Korean and are entirely different plants. Hallyeon, from South America, has round shield-shaped leaves and large orange flowers. Eclipta belongs to the daisy family, with narrow leaves and small white flower heads. When buying seed or dried material, check the botanical name and the Chinese characters together.

△ Brewing it long and taking it daily — Eclipta has also been handled as a medicinal herb. Brewing it as a tea a few times and taking a set quantity of it over a long stretch are two different things. The second lies outside what this entry covers, so ask a Korean medicine doctor or a pharmacist. Anyone allergic to daisy-family plants should be careful from the start.

Varieties

Eclipta (wild) — The Eclipta of Korean ground, common on paddy banks, ditch edges and wet margins
Dried whole herb (processing) — Cut at flowering and dried in the shade. Herbalists also sell it as mukhallyeon. Not a cultivar but a processing form

Source: Donguibogam, Herb Section 鱧腸 · Korean Plant Names Index