Polygonum weyrichii

(F. Schmidt ex Maxim.) Ronse Decr.

White Knotweed, Chinese knotweed

PolygonaceaeLeavesSeeds/NutsPotential hazards — see below
Caution — Parts of this plant may be toxic or require specific preparation. Verify with multiple sources before consuming.
Polygonum weyrichii
wikimedia · cc-by-sa
Wikimedia Commons - Qwert1234
Polygonum weyrichii
wikimedia · cc-by-sa
Wikimedia Commons

What to Eat

Edible parts: Leaves, Seeds

Young shoots are eaten cooked. The seeds, though rather small and fiddly to work with, can be dried and ground into a powder for use with cereals in making bread, porridge, and similar foods.

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.

Where to Find It

It suits hardiness zones 4-8.

Asia, Japan,

Countries: United Arab Emirates, Afghanistan, Armenia, Azerbaijan, Bangladesh, Bahrain, Brunei, Bhutan, China, Georgia, Indonesia, Israel, India, Iraq, Iran, Jordan, Japan, Kyrgyzstan, Cambodia, North Korea, South Korea, Kuwait, Kazakhstan, Laos, Lebanon, Sri Lanka, Myanmar, Mongolia, Maldives, Malaysia, Nepal, Oman, Philippines, Pakistan, Qatar, Saudi Arabia, Singapore, Syria, Thailand, Tajikistan, Timor-Leste, Turkmenistan, Turkey, Taiwan, Uzbekistan, Vietnam, Yemen

How to Identify

A perennial plant growing to 1.5 m (5 ft) tall, hardy to UK zone 5. Flowers from July to September. Hermaphroditic and insect-pollinated. Adapts to light sandy, medium loamy, and heavy clay soils with mildly acid to basic pH. Tolerates semi-shade or full sun, prefers moist soil, and can withstand maritime exposure.

How to Grow

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. Division can be done in spring or autumn. Larger divisions can go directly into permanent positions, but smaller divisions are better potted up and grown on in light shade in a cold frame until well established, then planted out in late spring or early summer.

Medicinal Uses

None known

Other Uses

None known

Wikipedia

Source ↗

A perennial plant growing to 1.5 m (5 ft) tall, hardy to UK zone 5. Flowers from July to September. Hermaphroditic and insect-pollinated. Adapts to light sandy, medium loamy, and heavy clay soils with mildly acid to basic pH. Tolerates semi-shade or full sun, prefers moist soil, and can withstand maritime exposure.

Notes

There are about 50 Polygonum species.

Names & Synonyms
Pleuripteropyrum weyrichii (F. Schmidt) H. GrossPolygonum savatieri Nakai
References (2)
  • Mem. Acad. Imp. Sci. St.-Peersbourg Divers Savans 9:234. 1859 (Prim. fl. amur.) (As Polygonum weyrichii)
  • Plants for a Future database, The Field, Penpol, Lostwithiel, Cornwall, PL22 0NG, UK. http://www.scs.leeds.ac.uk/pfaf/ (As Polygonum weyrichii)

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