Polygonum yokusaianum

Makino

Polygonaceae Edible: Leaves, Seeds Potential hazards — see below

iNaturalist· cc-by-nc

iNaturalist· cc-by

Summary

An annual plant reaching 0.6 m (2 ft) in height. Flowers appear from June to September, with seeds maturing July to October. The plant is hermaphroditic. It grows in light sandy, medium loamy, and heavy clay soils with mildly acid to basic pH. Tolerates semi-shade or full sun and prefers moist soil.

Description

Edible Uses

Young plants are eaten cooked, and the seeds can be used raw or cooked, though they are quite small and fiddly to work with.

Medicinal Uses

None known

Known Hazards

Although no specific mention has been made for this species, there have been reports that some members of this genus can cause photosensitivity in susceptible people. Many species also contain oxalic acid (the distinctive lemony flavour of sorrel) - whilst not toxic this substance can bind up other minerals making them unavailable to the body and leading to mineral deficiency. Having said that, a number of common foods such as sorrel and rhubarb contain oxalic acid and the leaves of most members of this genus are nutritious and beneficial to eat in moderate quantities. Cooking the leaves will reduce their content of oxalic acid. People with a tendency to rheumatism, arthritis, gout, kidney stones or hyperacidity should take especial caution if including this plant in their diet since it can aggravate their condition.

Distribution

It is a temperate plant.

Where It Grows

Asia, Japan,

Cultivation

We have very little information on this species and do not know if it is hardy in Britain, though it should be possible to grow it as a spring-sown annual in this country. The following notes are based on the general needs of the genus. Succeeds in an ordinary garden soil but prefers a moisture retentive not too fertile soil in sun or part shade. Repays generous treatment. Plants seem to be immune to the predations of rabbits.

Propagation

Sow seed in spring in a cold frame; germination is usually free and easy. Once seedlings are large enough to handle, prick them out into individual pots and plant out during summer if they have reached sufficient size. If not, overwinter in a cold frame and plant out the following spring after the last expected frosts.