- Type
- Leafy Greens
- Difficulty
- Easy
- Season
- Spring·Fall
- Sowing
- From seed
Creeping wood sorrel
Oxalis corniculata
Oxalic acid · three heart-shaped leaflets with a sour bite
Creeping wood sorrel arrives on its own along the edge of a plot and in the cracks between paving stones. Three heart-shaped leaflets sit on each stalk, the flowers open in five yellow petals, and at dusk the leaflets fold downward. Chew a leaf and it tastes sour; that sourness is oxalic acid. The Donguibogam lists it in the Herb section as 酢漿草 and records the old Korean name as gwoiseung-a, adding that people commonly called it 酸車草 and that children picked and ate it. Its note that the plant grows everywhere on low, damp ground still holds exactly. Because the sourness is oxalic acid, though, this is not a plant to dress by the plateful — a few leaves scattered over a salad or floated in a glass of water is the usual measure. It is easy to confuse with clover: round leaflets with a pale band mean clover, three hearts with a sour taste mean wood sorrel.
Year-Round Calendar
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Where It Grows
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Wild population
It comes up on its own along field edges, roadsides and flower beds throughout the country. Harvest April, May, June, September, October
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- Wild population Common in fields and along roadsides in every region.
- Wild population Common on roadsides and in yards throughout the country.
Its origin is not clearly known, and it has now spread as a weed across the world, from temperate to tropical regions, so colouring in every country where it grows would leave the map meaningless. It is not a cultivated crop and no production figures exist, so only East Asia is marked, where its use as namul (an edible wild green) and in folk remedies has carried on.
- Optimum
- 15~25℃
- Range
- 5~35℃
- Hardiness
- Hardy
A small perennial that grows anywhere the sun reaches. It stands up well to heat and dry ground, and it is not fussy about soil, so it roots in flower-bed soil, in the surface soil of pots, and in the cracks between paving blocks. When it dries out it folds its leaves and leaves them folded.
In Korea Nationwide
It comes up on its own at field edges, along roadsides and in the cracks between paving blocks nationwide. No one plants it: the seed pods burst and scatter it far.
How to grow
- Light
- Good in sun, willing in part shade. It seeds itself around without being planted
- Soil and depth
- Not fussy. It roots in bed soil, the surface of a pot, even a crack between paving stones
- Spacing
- Not planted in rows. In a plot the useful job is deciding how far it may spread
- Watering
- Water when the surface dries. Let it dry out and the leaflets stay folded
- Feeding
- No feeding. Rich ground gives leafy growth and a weaker sour taste
- Harvest
- Pick a few leaves as needed from April into autumn. The leaf tastes the same after flowering
What makes the difference. Rinse the picked leaves in cold water, shake them dry and use them at once. Once wilted they lose both shape and sourness and never recover
Why this one is harder. Ripe seed capsules split and fling seed some distance, so one season is enough to spread it across a whole plot. To keep it where you want it, strip the capsules as soon as the flowers drop
Common problems
- Aphids You will see They settle on flower stalks and new leaves and everything turns sticky What to do Wash them off with a jet of water. This is a plant you eat leaf by leaf, so use no sprays
- Spider mites You will see Leaves go dull and pale with very fine webbing underneath What to do Spray water on the undersides too and keep it out of hot, dry corners
- Slugs You will see Leaves and flowers gone overnight What to do Collect them by hand in the evening and empty any water standing in the pot saucer
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 — chojangcho (酢漿草). The Donguibogam lists the plant in its Herb section as 酢漿草 and gives the old Korean name as gwoiseung-a. It records a cold nature, a sour taste and no toxicity. It grows on low, damp ground and is found everywhere, the entry says, adding that children pick and eat it and that people commonly call it 酸車草. What an old medical text wrote differs from how it is judged today.
Sourness and oxalic acid. Compositional analysis confirms that the sourness of Oxalis species comes from oxalic acid. The genus name Oxalis and the name of the acid share the same root. This is a compositional record.
Leaves that fold. At dusk the three leaflets fold downward and open again in the morning. Botany treats this daily movement as nyctinasty. This is a record of form and behaviour.
Nutrition
- Oxalic acid (the sourness of leaf and stem) — the organic acid behind the sour taste
- Vitamin C (present in the leaves) — one of the water-soluble vitamins
- Flavonoids (present in the leaves) — phenolic compounds reported across the genus Oxalis
The sourness is oxalic acid The sour taste comes from oxalic acid, the same organic acid found in spinach and curly dock. It binds calcium into a form that dissolves poorly. That is why it is handled as a flavouring used a few leaves at a time rather than a vegetable eaten in quantity.
Vitamin C The leaves carry vitamin C. Sourness and vitamin C are separate things, and a sharper taste does not mean a higher figure.
Flavonoids Flavonoids are reported in Oxalis species. This entry stays with the compositional record.
How much is a normal amount A few leaves over a salad or floated in water is the usual use. It is not handled as a green to dress by the plateful. Livestock records report cattle and sheep coming to harm after grazing heavily on oxalate-rich plants, which is reason enough for people to keep the amount small too.
Pairings
○ Scattered over a salad — A few leaves on top of a salad give sourness without squeezing a lemon. The leaves are thin and go limp in dressing, so add them just before serving.
○ Cold water or sparkling water — Leaves and flowers floated in cold water give up a faint sourness. Do not steep them long; a few per glass is enough.
○ White fish and eggs — The sourness cuts through richness. Lay the leaves on raw, over the cooked dish, so both colour and taste survive.
△ Eating a large amount at once — Because oxalic acid is the source of the sourness, wood sorrel is not eaten by the plateful. Use a few leaves as a garnish, and keep an eye on the amount when a child is picking it for fun.
△ Anyone managing oxalate intake — Anyone who has had a calcium oxalate stone and is managing high-oxalate foods should leave wood sorrel out. Handle it in the same category as spinach and chard.
△ Clover confusion, and where you pick — With three leaflets it grows mixed in with clover. Clover has rounded leaflets with a pale band and no sourness; wood sorrel has three hearts and a sour taste. Do not pick from paving cracks, roadsides or beds where dogs walk. Oxalate-rich plants are not advisable for dogs and cats either, so households with pets should also watch where the pot goes.
Varieties
- Creeping wood sorrel (seed) — The commonest species. Stems run along the ground and the flowers are yellow
- Upright yellow sorrel (Oxalis stricta) (seed) — The upright-stemmed kind. Flower and taste match the creeping sort
- Keun-gwaengibap (Oxalis obtriangulata) (seed) — A woodland species of mountain shade, with larger leaves and white flowers veined in red
- Ornamental oxalis (sarangcho) (bulb) — The pot-grown ornamental group, some with large purple leaves. Not planted for eating
Source: Donguibogam, Herb Section 酢漿草 · Korea National Arboretum, Korean Plant Names Index