Polygonum thunbergii
Siebold. & Zucc.
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iNaturalist· cc0
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iNaturalist· cc0
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Summary
An annual plant reaching 1 m tall with hermaphroditic flowers pollinated by insects. Flowers appear July to September with seeds ripening August to October. Grows in light sandy, medium loamy, and heavy clay soils across mildly acidic to mildly alkaline pH ranges. Tolerates semi-shade or full sun and prefers moist to wet soil conditions.
Description
A herb. It grows 50-70 cm tall. The leaves are 5-7 cm long. They are triangle shaped. They are prickly underneath. The flowers have hairs.
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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 to subtropical plant. It grows in wetlands. In Vietnam it grows at 1,500 m above sea level.
Where It Grows
Asia, China, Indochina, Japan, Korea, SE Asia, Vietnam,
Cultivation
We have very little information on this species and do not know if it is hardy in Britain, though judging by its native range it should succeed outdoors in most parts of the country. It is a polymorphic species. 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.
Other Uses
None known
Notes
There are about 50 Polygonum species.
Synonyms
Also Known As
Nghe Thunberg
References (3)
- Chen, B. & Qiu, Z., Consumer's Attitudes towards Edible Wild Plants, Ishikawa Prefecture, Japan. p 24 www.hindawi.com/journals/ijfr/aip/872413.pdf
- Plants for a Future database, The Field, Penpol, Lostwithiel, Cornwall, PL22 0NG, UK. http://www.scs.leeds.ac.uk/pfaf/
- Zhang, Y., et al, 2014, Diversity of wetland plants used traditionally in China: a literature review. Journal of Ethnobiology and Ethnomedicine. 10:72
