Udo

Aralia cordata

Diterpene acids and fibre · a thick shoot that rises straight from the ground

Udo is not a tree but a herbaceous perennial of the ginseng family, and in spring it sends shoots as thick as a thumb straight up out of the ground. It is a different species from durup, whose shoots are picked at the tips of a tree, though the two sit side by side on the spring stalls of a traditional market. The Donguibogam lists it in the Herb section as dokhwal and records the Korean name as ttat-dulheup, which has carried through to the modern ttangdureup (ground durup) unchanged. The name dokhwal is explained by the single stem standing straight and refusing to shake in the wind, and the text adds a second name, dokyocho, from the notion that it stirs by itself even with no wind at all. The shoots carry a harsh edge, so they are always blanched in boiling water and rinsed cold before use. Blanched, they are dressed in vinegared chilli paste or fried in batter; the aroma is gentler than durup but the texture is coarser and crisper. Japan has long grown it under a mound of soil or rice husk to keep the light off and bring the shoots up white and tender. Once established it returns to the same spot every year, but no shoots are taken in the first or second season while the crown builds.

Year-Round Calendar

Sowing

Harvest

Where It Grows

Main producer Major producer Wild population Latitudes at 15–25℃ Zoom and pan to explore · temperatures are rough zonal averages

Main producer Grown here in the greatest quantity, under the name udo. In Tachikawa in Tokyo and in Gunma and Tochigi, blanching cultivation, raising the shoots white in soil or inside underground pits, has developed.
Major producer Grows wild on the foothills of the central and southern regions, and is grown in fields in the mountain districts of Gangwon and Gyeonggi for use as a spring green vegetable (namul). Harvest April, May
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Wild population Grows wild in the mountains of the northeast and of Central China.

A perennial herb native to the mountains of Korea, China and Japan, with no single country identifiable as its place of origin. Blanching cultivation, in which the shoots are kept out of the sun and raised white, developed in Japan, which still produces the most. One overlapping medicinal name is worth setting straight: in Korea, dokhwal means this species (Aralia cordata), but what China uses under the name duhuo is a different plant in the carrot family (Angelica biserrata).

Optimum: 15~25℃
Range: 5~30℃
Hardiness: Hardy

A perennial that grows on mountain foothills where summers stay cool. It overwinters (survives the winter in the ground) on a thick root and withstands even the cold of the central mountain districts, though the root rots where water collects. When the ground thaws in spring, thick shoots push straight up.

Harvested 2–3 years after planting. In the year the roots are divided and planted, and again the following year, no shoots are picked and the clump is left to build up. Once the plant is established, two or three thick shoots are harvested each spring.

In Korea Nationwide

Grows wild on the foothills of the central and southern regions, and is grown in fields in the mountain districts of Gangwon and Gyeonggi for use as a spring green vegetable (namul). The shoots that come up in spring are harvested in April and May.

How to grow

Light: Half a day of sun or more. In deep shade the shoots come up thin
Soil and depth: Loose, free-draining soil at least 40cm deep. Standing water rots the crown
Spacing: 60 to 80cm between plants. A mature clump stands as tall as a person, so keep it off the path
Watering: Keep it from drying out through the first year. Once established, water only through a summer drought
Feeding: Work a spadeful of compost around the base in November or December once the top growth has died back. Heavy nitrogen makes the shoots soft
Harvest: April and May. Cut at the base when the shoot stands about 20cm and just before the leaves open. Take only two or three thick shoots per crown and leave the rest to build the plant. Take none in the first or second year after planting

What makes the difference. Mound 20cm of soil or rice husk over the crown before the shoots rise and they come up white and tender, with less of the harsh edge

Why this one is harder. The root is thick and runs deep, so an established crown is hard to move, and a mature plant stands taller than a person and shades whatever grows beside it. Choose its spot at planting — the north end of a plot, where cast shade does no harm

Common problems

Aphids You will see Colonies on shoot tips and young leaves, turning sticky What to do Wash off with a jet of water; if it recurs, use an egg-yolk oil spray. Observe pre-harvest intervals where shoots are to be picked
Root rot You will see Shoots fail to appear in spring, or rise part way and collapse soft What to do Avoid spots where water sits and raise the bed. Dig out rotted crowns and do not replant in the same place
Leaf blight You will see Browning that starts at the leaf margins after the rainy season and spreads What to do Thin the clumps to open an air path and clear away affected leaves. Water in the morning so the foliage is not wet overnight

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 — dokhwal (獨活). The Donguibogam lists the plant in the Herb section as dokhwal and records the Korean name as ttat-dulheup. Its nature is set down as neutral, with a note that some call it slightly warm; its taste as sweet and bitter, with a note that some call it pungent; and it is described as having no toxicity. It records that the plant grows in hills and fields, and that the root is dug in the second, third, ninth and tenth lunar months and dried in the sun. On the name, it says the plant does not shake when the wind blows and stirs by itself when there is none, hence the alternative name dokyocho, and adds that a single stem rising straight and unmoved by wind is what dokhwal means. It also records the sorting criterion of the day: purple material with crowded nodes was taken as gangwhal, yellow material in lumps as dokhwal. What an old medical text wrote differs from how it is judged today.

A name that carried through. The Korean name recorded in the original, ttat-dulheup, carried straight through to today's ttangdureup. The distinction between shoots taken from a tree and shoots that rise from the ground has held in the naming for more than four hundred years. Material traded under the name dokhwal in modern markets, however, sometimes comes from a different genus, so the name alone does not settle the species.

Compounds reported in the root. Diterpene acids of the continentalic and kaurenoic type have been isolated from udo roots in repeated analyses. Saponins, commonly reported across the ginseng family, are treated in the same literature. These are compositional analyses and nothing beyond that.

Nutrition

Diterpene acids (isolated from the roots) — compounds of the continentalic and kaurenoic acid type
Saponins (reported across the ginseng family) — partly drawn into the water during blanching
Dietary fibre (the coarse grain of the shoot) — the fibre behind the substantial bite
Essential oil (the aroma of shoot and root) — volatile fraction behind the family's characteristic scent

It has to be blanched Udo shoots carry a harsh edge and are not eaten raw. The basic preparation is two to three minutes in boiling salted water followed by a cold rinse, and the blanching water is thrown away. Blanching takes the harshness out and brightens the colour.

A different species from durup Durup is the new shoot of a tree; udo is the shoot of a herbaceous perennial. They share a plant family but not a species, and they differ in the thickness of the shoot and the strength of the aroma. Side by side on the same stall, they are still better handled as two different ingredients.

What the root analyses report Diterpene acids of the continentalic and kaurenoic type have been isolated from udo roots. Saponins, commonly reported across the ginseng family, are discussed in the same work. This entry stays with the compositional record; the root is a separately traded medicinal material and is put to different use from the shoots this entry covers.

The grain of the shoot Among spring greens the shoot is thick, so the bite is coarse rather than delicate. Fibre stiffens as the shoot opens and the leaves unfurl, which makes picking on time a matter of texture as much as aroma. Split the thick base lengthwise before blanching so it cooks evenly.

Pairings

○ Dressed in chogochujang — Tear the blanched shoots by hand and dress them in vinegared chilli paste. The acidity covers the harsh finish. Shake them dry rather than wringing them out, or the grain breaks up.

○ Perilla oil and salt — Dressed with nothing but perilla oil and salt, the aroma stays where it is. A light hand with seasoning keeps the vegetable in front. Crush the sesame between your fingers as you scatter it.

○ Batter and egg — Halve the blanched shoots, coat them thinly and pan-fry. Score the thick base so it cooks through evenly. Frying softens the harsh edge enough for children.

△ Never eaten raw — Udo shoots are not eaten raw. The harsh edge rasps the throat and can unsettle the stomach, so blanch for two to three minutes in boiling water and rinse cold before use. Throw the blanching water away.

△ Do not dig a shoot on thickness alone — Finding udo on a spring hillside by looking for a thick shoot rising straight from the ground is a risky habit. Pokeweed sends up thick, reddish shoots at the same season and is not eaten. Udo shoots are downy along their whole length, carry the aroma of the ginseng family, and open into twice- or thrice-divided compound leaves. If you are not certain, do not dig.

△ The root is not something to decoct at will — The medicinal material sold as dokhwal is the root of this plant, and it is a herbal medicine. This entry covers the spring shoots, and digging the root to decoct on your own initiative is not advisable. Material sold under the name dokhwal in markets sometimes comes from plants of an entirely different genus, so both species and plant part need checking.

Varieties

Open-field grown (root division) — Grown in full light, the shoots stay green and the aroma runs stronger
Blanched (soil-mounded) (root division) — Grown under a mound of soil or rice husk that keeps the light off. White, tender, and less harsh
Wild-grown (wild) — Thinner shoots than cultivated stock, with both aroma and bitterness running strong

Source: Donguibogam, Herb Section 獨活 · Rural Development Administration (Nongsaro) · Korea National Arboretum