- Type
- Trees & Vines
- Difficulty
- Easy
- Season
- Spring
- Sowing
- From seed
Japanese Milkweed
Metaplexis japonica
White latex · a vine common along field edges
Japanese milkweed is a twining herb that climbs field banks and roadside fences. Cut a stem or a leaf and white latex runs out, which is the clearest mark for recognising this group. The young shoots of spring are blanched and dressed, and local records describe peeling unripe pods and eating the soft interior. When the pods split in autumn the seeds sail off on white plumes, and more people know the plant from that than from anything else. The Donguibogam lists it in the Herb section as namaja (蘿摩子), giving the Korean name as saebak. It records a warm nature, a taste sweet and pungent, and no toxicity, and sets down the form: found everywhere, growing as a vine, releasing white sap when cut. It notes that the leaves are used as the seed is, and adds that it is also called jakpyo (雀瓢). Since several unrelated vines run white latex, digging the root is not something to do; this entry stops at blanched young shoots.
Year-Round Calendar
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Where It Grows
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Wild population
Common throughout the country in fields, on field banks and along fences. Harvest April, May
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- Wild population Common in the fields of the northeast and North China.
- Wild population Common in fields from Hokkaido to Kyushu.
- Wild population Native to Primorye and the Amur basin.
It is a wild plant of temperate East Asia, ranging across Korea, China, Japan and the Russian Far East. Nowhere is it grown as a field crop, so there are no producing regions to rank by output, and the map shows only its native range. It has been introduced and naturalised in North America and parts of Europe, but it is not treated as an edible green there.
- Optimum
- 15~25℃
- Range
- 5~30℃
- Hardiness
- Hardy
It grows in sunny spots along field banks and roadsides. It is unfussy about dry soil or gravel ground, and in winter the vine dies back and the plant comes up again from the rhizome underground. The seeds carry a tuft of silky hairs and travel far on the wind.
Harvested 1–2 years after planting. Sow the seed and the shoots are worth picking from the following year. Once it takes hold it carries on by rhizome, coming up in the same place year after year.
In Korea Nationwide
Common throughout the country in fields, on field banks and along fences. The young shoots are picked in spring, and it is rarely planted and grown.
How to grow
- Light
- Sunny field banks and fences. It will grow in part shade but sets fewer pods
- Soil and depth
- Not particular. It roots in dry ground and runs across gravel
- Spacing
- The vine runs over two metres, so one plant along a fence line is plenty
- Watering
- No watering needed. Keep it from drying out through the first year only
- Feeding
- No feeding. Rich ground builds leaf and cuts the pods
- Harvest
- April and May. Pinch off the shoots by hand at about a hand-span, while the leaves are still soft. Unripe pods are picked in late summer, peeled, and checked inside
What makes the difference. Blanch picked shoots in boiling water and rinse cold before use. Discard the blanching water, and never eat them raw
Why this one is harder. It spreads two ways at once, by rhizome and by airborne seed, so within a few years it crosses the bank. Pick the pods before they split, and cut the rhizomes back in autumn to fix the boundary
Common problems
- Aphids You will see Colonies on shoot tips and flower clusters What to do Wash them off with a jet of water. Do not spray a vine you intend to pick from
- Spreading You will see Vines appear where nothing was planted and rhizomes run sideways What to do Cut the rhizomes back in autumn to fix the boundary. Picking the pods before they split keeps the seed from flying
- Powdery mildew You will see Leaves go pale in late summer and drop early What to do Thin the vines for airflow and take off the affected leaves
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 — namaja (蘿摩子). The Donguibogam lists the plant in its Herb section as namaja (蘿摩子) and gives the Korean name as saebak. It records a warm nature, a taste sweet and pungent, and no toxicity. It sets down the form — found everywhere, growing as a vine, releasing white sap when cut — and notes that the leaves are used as the seed is. It adds that the plant is also called jakpyo (雀瓢). The entry quotes the Bencao. This is a historical medical record and differs from modern medical judgment.
Glycosides of the genus Metaplexis. Pregnane-type glycosides have been isolated from Metaplexis species in repeated analyses. That white latex is a shared character of this group has likewise been addressed in plant taxonomy. These are compositional analyses and have nothing to do with preventing or treating disease.
Nutrition
- White latex (runs from cut stems and leaves) — the sap that marks out this group
- Pregnane glycosides (reported across the genus Metaplexis) — glycosides isolated from this group
- Dietary fibre (forms the grain of the young shoot) — what increases and coarsens as the shoot lengthens
Blanched, not raw The young shoots are blanched before use. Boil briefly, rinse cold, and throw the blanching water away. The white latex leaves a harsh edge, so give the shoots a rinse under running water before they go in.
The white latex Cut stems and leaves release white latex. Analyses report pregnane-type glycosides isolated from the genus Metaplexis. If the sap gets on your hands while trimming, wash it off without touching your eyes or mouth.
Unripe pods Local records describe peeling pods that have not yet hardened and eating the soft interior. Once the pod ripens and splits, the inside is nothing but plumed seed and is not eaten. Split a pod and use only the ones that are white and soft inside.
Pairings
○ Dressed with doenjang — Squeeze the blanched shoots lightly and dress them with soybean paste and sesame oil. A mild paste covers the harsh finish.
○ Mixed with other spring greens — A picking of milkweed shoots rarely amounts to much on its own, so it is usually dressed together with other spring greens. Blanch together only what cooks in the same time.
○ Perilla oil and sesame — Perilla oil and sesame seed thicken the aroma of the blanched shoots. Seasoning lightly leaves the vegetable itself in front.
△ Digging the root — The root of Japanese milkweed is not dug for use. Several vines run white latex, so a root alone will not identify the plant, and supply of the related Cynanchum wilfordii was once found mixed with Cynanchum auriculatum. Where a root is needed as a herbal material, buy standard-grade material rather than anything dug from the fields.
△ Ripe pods — A pod that has begun to split is not eaten. The inside is already packed with plumed seed and will not chew. Split the pods and use only the ones that are white and soft inside.
△ Picking on field banks and roadsides — Do not pick along banks that have been sprayed or roads carrying traffic. The vine runs low, so soil and spray reach it directly. Rinse what you pick several times under running water.
Varieties
- Japanese milkweed (wild) — The common vine of field banks. Heart-shaped leaves, white sap when cut
- Cynanchum wilfordii (distinction) — A relative in the same group whose root is used as a herbal material. Its market supply was once found mixed with Cynanchum auriculatum
Source: Donguibogam, Herb Section 蘿摩子 · Korea National Arboretum, Korean Plant Names Index