- Type
- Herbs & Aromatics
- Difficulty
- Easy
- Season
- Spring·Summer
- Sowing
- Transplant
Houttuynia
Houttuynia cordata
Flavonoids · a fishy-scented plant for part shade
Houttuynia is a perennial in the Saururaceae, and rubbing a leaf releases a smell close to raw fish — hence its other Korean name, eoseongcho, the fish-smell herb. Heart-shaped leaves alternate up the stem, and in May and June a flower spike rises above four white bracts set in a cross. It spreads hard by rhizome, and planted straight into a yard it will own one side of it within a few years, so in the city it is grown in a pot in part shade or inside a root barrier. The Donguibogam lists it in the Vegetable section as 蕺菜 with the Korean name myeol, giving it a slightly warm nature, a pungent taste, and recording it as toxic. The same entry notes that people are fond of eating it raw, while adding a caution against eating it over long periods.
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Where It Grows
- Main producer In Guizhou and Sichuan it goes by the name zhe'ergen, and both the rhizomes and the leaves are grown in fields as a vegetable.
- Major producer In the north and the Red River Delta it is grown as a fresh vegetable eaten raw, and it is always on the market stalls.
- Wild population It grows wild over wide areas on shaded, damp ground from Honshu southward.
- Wild population It grows wild in the damp partial shade of the southern provinces and Jeju.
It is native to the subtropical and temperate wetlands that run from East Asia through the Himalayas and into Southeast Asia, and cannot be pinned to any one country. In southwestern China and Vietnam it is a field crop grown as a vegetable; in Korea and Japan it is more often gathered from wild stands and dried for use.
- Optimum
- 20~28℃
- Range
- 10~32℃
- Hardiness
- Hardy
A wetland plant of partial shade, growing where the ground holds moisture for long stretches. It carries its rhizomes through the cold and so overwinters — survives the winter in the ground — even in the central regions, but its wild range leans toward the south, where winters are milder. Under direct sun all day the leaves thicken and their margins dry out.
In Korea Central Korea and south
It grows wild in the shade along streamsides and paddy banks in the southern provinces and on Jeju. So long as the rhizomes do not freeze it overwinters even in the central regions, but in pots, soil that freezes and thaws over and over will damage the roots.
How to grow
- Light
- Part shade with two to four hours of sun. Full-day direct sun thickens the leaves and dries the margins
- Soil and depth
- Soil that holds moisture. Mixing about 30 percent leaf mould into potting compost gives broader leaves
- Spacing
- 20 to 30cm between plants. One or two plants only in a 25cm pot
- Watering
- Water as soon as the surface dries. It likes wet feet enough to tolerate a little standing water in the saucer
- Feeding
- A handful of well-rotted compost in spring is enough. Heavy feeding gives big leaves but a weaker scent
- Harvest
- Leaf and stem are at their fullest around flowering, June to August. Cut with scissors, leaving 10cm of stem. Two cuts a year are possible, and the rhizomes are dug in autumn by tipping the pot out
What makes the difference. It spreads hard. To plant it in the ground, sink a pot with the base cut out and plant inside it so the rhizomes stay caged. In a pot on its own, divide the clump every three years or the centre goes bare
Why this one is harder. The smell divides people sharply. If fresh leaf is too much, start with dried or pan-toasted leaf; and if it still does not suit, keeping the variegated Chameleon as an ornamental instead of a tea plant is a fair outcome
Common problems
- Slugs You will see Holes in the new leaves and silver slime trails visible in the morning What to do Collect by hand after dark and clear fallen leaves and weeds from around the pot
- Spider mites You will see In strong sun and dry air the leaf undersides turn rough and the colour fades to a dull grey What to do Mist the undersides and move the pot to a shadier spot
- Fungus gnats You will see Small black flies drifting over the soil surface. Worse in a pot kept permanently wet What to do Let the top 1cm of soil dry between waterings and stand a yellow sticky trap in the pot
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
What the Donguibogam records — the name and its nature. The Donguibogam lists the plant in the Vegetable section as 蕺菜, with the Korean name myeol. It gives a slightly warm nature, a pungent taste, and records it as toxic. It notes the plant grows everywhere, in hills and among fields, and that people are fond of eating it raw, while adding a caution against eating it over long periods. This is a historical medical record and differs from modern medical judgment.
Analyses of the aroma compounds. Studies of the volatile fraction of houttuynia leaf report decanoyl acetaldehyde as the principal compound behind its characteristic smell. The same work records that drying and heating reduce that compound substantially. This concerns composition only and has no bearing on the prevention or treatment of disease.
Nutrition
- Decanoyl acetaldehyde (the main compound behind the smell of a crushed leaf) — highly volatile, and much reduced by drying
- Quercitrin and rutin (flavonoid glycosides present in the leaf) — involved in the colour and the astringent finish of the tea
- Potassium (concentrated as the leaf dries) — a mineral common in leafy greens
The smell is volatile The characteristic smell comes from decanoyl acetaldehyde and other volatile compounds. Volatile means what it says: drying the leaves in shade or toasting them in a dry pan drives much of it off. That is why a chewed fresh leaf and a cup of tea from dried leaf smell like two different plants. Anyone put off by the raw scent is better starting with dried leaf.
Flavonoids in the leaf Quercitrin and rutin have been reported among the flavonoid glycosides in the leaf. These are involved in the pale yellow of the brew and the astringency that lingers at the end. Water that is too hot pulls that astringency out hard, so brew around 90°C for about three minutes. Successive infusions run steadily lighter in both colour and taste.
Which parts are eaten, and how much In Korea the leaves and stems are usually dried and drunk as tea. In Yunnan and in Vietnam the rhizome is more common, dressed with vinegar and chilli as a side dish. Either way this is not a vegetable eaten in quantity. Given that the old record marks it toxic and warns against long use, it is sensible to settle on a set amount rather than drink it freely.
Pairings
○ Pan-toasted leaf tea — Pick leaves in June or July and either dry them in shade or toast them slowly in a dry pan. Toasting cuts the fishy note and brings up a roasted aroma. Brew about three minutes near 90°C and keep the rest sealed in a cool cupboard.
○ Lemon or maesil syrup — Acidity holds the fishy note down. A slice of lemon or a spoon of green plum syrup in cooled tea makes a first cup far easier. Add it after the tea has cooled — into hot tea it simply evaporates. Korean Plum (Maesil)
○ Meat wraps and vinegar salads — In Vietnam and Yunnan the young leaves are eaten as a wrap alongside grilled meat. Dressed with vinegar, sugar and chilli, the smell softens considerably. For a salad the crisp rhizome works better than the leaf.
△ Heart-shaped leaves gathered wild — Plenty of plants carry heart-shaped leaves, so leaf shape alone is no basis for gathering. Aristolochia contorta and Metaplexis japonica both climb by twining, while houttuynia stands upright and never twines, and a rubbed leaf smells of fish immediately. Aristolochic acid, present in Aristolochia contorta, is banned from food and medicine in Korea and abroad. Leave anything that climbs, and use only what came from your own pot.
△ Large amounts over long periods — The Donguibogam records this plant as toxic and, while noting that people like to eat it raw, adds a caution against eating it over long periods. Rather than making several cups of tea a daily habit, it is better to fix an amount. Anyone on medication, pregnant or breastfeeding should speak to a doctor or pharmacist first.
△ Plants dug from roadsides and field edges — Houttuynia spreads by rhizome and turns up readily along roads and on herbicide-sprayed field margins. Whatever the plant takes up from that ground stays in the rhizome. For tea or for the table, harvest only from a pot or a patch you grew yourself.
Varieties
- Native houttuynia (seedling) — Deep green leaves and the strongest scent. This is the line planted for leaf tea
- Chameleon (seedling) — Leaves splashed with red and yellow. Sold as an ornamental, and less vigorous in proportion to the variegation
- Flore Pleno (seedling) — Layered double white bracts. Grown for the flower; it produces fewer leaves than the native form
Source: Donguibogam, Vegetable Section 蕺菜 · Rural Development Administration (Nongsaro) · Korea National Arboretum, Korea Biodiversity Information System