The Plant Named After Cat Food — Korea's Wood Sorrel and Its Surprisingly Good Taste

 The Plant Named After Cat Food — Korea's Wood Sorrel and Its Surprisingly Good Taste

괭이밥 means cat food.

Not in a metaphorical sense. Not as a folk observation about the plant being fit only for animals. The name comes from a straightforward old belief: cats eat this plant when their stomachs are upset. 괭이 is an old Korean word for cat. 밥 is food, or a meal. Cat food.

Whether cats actually seek out this plant medicinally is one of those questions that was settled by consensus long before anyone thought to study it scientifically. But the name stuck, and now one of Korea's most common and cheerful little plants is permanently associated with feline digestive complaints.

The plant itself deserves better. The leaves taste like lemon. The flowers are a clean, vivid yellow. It grows in the gap between a granite boulder and a footpath, in the crack of a wall, in any small pocket of disturbed soil that gets reasonable light. It's been in Korea for thousands of years and has spread to every continent on earth. And most people who pass it every day have no idea it's edible.

 The Plant: 괭이밥 (Oxalis corniculata)

**Korean name:** 괭이밥  

**English common name:** Creeping Wood Sorrel, Yellow Wood Sorrel  

**Scientific name:** *Oxalis corniculata* L.  

**Family:** Oxalidaceae (괭이밥과)  

**Blooms:** April – October  

**Height:** 5–30cm, creeping  

**Native range:** Cosmopolitan — origin uncertain, now on every continent except Antarctica  

**Toxicity:** Generally safe in small amounts. Contains oxalic acid — see below.

*Oxalis corniculata* is a low, creeping perennial that spreads by stolons and self-seeds prolifically. The leaves are trifoliate — three heart-shaped leaflets arranged like a clover, folding inward at night and on overcast days in a movement called nyctinasty. The flowers are small, bright yellow, five-petaled, held on slender stems above the leaf canopy. After flowering, the plant produces narrow cylindrical seed pods that, when ripe, eject their seeds explosively when touched — a dispersal mechanism that has helped 괭이밥 colonize every warm-temperate region on earth.

The stems and leaves are green in some individuals, deep purple-red in others. Both color forms occur in Korea and are the same species. The purple-stemmed form is particularly striking when the yellow flowers open above it.

 The Lemon Taste and What Causes It

The sour taste of 괭이밥 is one of its most distinctive features and the most relevant thing to know about eating it.

The sourness comes from oxalic acid — the same compound that makes rhubarb tart and spinach slightly astringent. In 괭이밥, the concentration is high enough to be clearly perceptible: bite a leaf and you get an immediate, clean, lemony sourness. It's quite pleasant in small quantities. It's the reason the plant was historically used as a flavoring — a few leaves added to salads or soups to provide tartness, similar to how sorrel (*Rumex* species) is used in European cooking.

The oxalic acid is also why the plant should not be eaten in large quantities. Oxalic acid binds to calcium in the body, forming calcium oxalate crystals, and in high concentrations can contribute to kidney stones in susceptible individuals and cause digestive irritation. A few leaves as a garnish or trail snack is fine. Eating large amounts regularly is not advisable, particularly for people with kidney disease or a history of kidney stones.

Interestingly, cooking reduces the oxalic acid content significantly — the same reason spinach, which also contains oxalate, is often blanched before eating.

 What Koreans Did With It

In Korean folk tradition, 괭이밥 was used both as food and medicine, though modestly in both roles — the oxalic acid content was presumably understood even without chemical terminology, through simple observation of what happened when people or animals ate too much.

The young leaves were used as a souring agent in cooking — added to 국 (soup) or eaten raw in small quantities as a 나물. The flavor was specifically valued for its tartness rather than its bulk, so 괭이밥 functioned more as a seasoning than a main ingredient.

Medicinally, 괭이밥 was used in Korean and East Asian folk medicine to treat urinary tract complaints, to reduce fever, and to apply topically to insect bites and minor skin irritations. The plant was also used to treat snakebite in some regional traditions — applied as a fresh poultice to the wound. Modern research has confirmed antimicrobial and anti-inflammatory properties in the plant's compounds, though the snakebite application has no documented pharmacological support.

In Chinese traditional medicine, 괭이밥 is known as 酢漿草 (*cu jiang cao*) — vinegar herb — named for the same sour taste. It was used to clear heat, cool the blood, and treat damp conditions.

 The Folding Leaves

One of the more interesting things about 괭이밥 is its leaf movement.

The three leaflets fold downward along their midribs at night, in shade, and in response to water loss stress — the plant physically closes itself. In the morning, they reopen. This movement, called nyctinasty when triggered by the day-night cycle, is driven by changes in turgor pressure in specialized cells at the base of each leaflet. The plant is not exactly sleeping, but the visual effect is strikingly similar.

If you find 괭이밥 on an overcast day and the leaves look collapsed and droopy, it's probably not sick — it's just responding to the light level. Check back in full sun.

The seed pods also move. When ripe, the elongated pods dry and build tension. Touch one and it fires its seeds outward with enough force to scatter them several centimeters. A single plant can produce thousands of seeds this way. Combined with the creeping stolons that root at nodes, this gives 괭이밥 two simultaneous methods of spread — vegetative and ballistic. It's a very effective plant.

 The Photo I Keep Coming Back To

The last photo in this set is the one I find most satisfying.

괭이밥, sprawling along the base of a granite boulder. And scattered across the ground around it, the fallen petals of 철쭉 — azalea — still pink, still holding their color even in death. The azalea is one of the great flowering spectacles of the Korean spring: entire mountainsides turning pink, hundreds of people climbing to see it. 괭이밥 is what everyone steps over on the way up.

Both plants are growing in the same few square meters. One of them has festivals organized in its honor. The other has a name that means cat food.

I'm not sure what conclusion to draw from that. But I think about it.

 ⚠️ Disclaimer

This blog documents Korean plants and their traditional uses for educational and cultural purposes only. Nothing here is medical advice. 괭이밥 contains oxalic acid and should not be consumed in large quantities, particularly by people with kidney disease, kidney stones, or related conditions. If you're considering foraging or using any wild plant medicinally, consult a qualified healthcare provider first.

*Photographed in Korea, May 2026. All field photography by The Korean Herbalist.*

**Tags:** 괭이밥, Oxalis corniculata, creeping wood sorrel, Korean edible weeds, Korean traditional medicine, oxalic acid plants, Korean spring plants, Korean foraging, Oxalidaceae Korea, urban wildflowers Korea