Polygonum persicaria

Red Leg, Spotted ladysthumb

PolygonaceaeLeavesSeeds/NutsShootsPotential hazards — see below

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What to Eat

Edible parts: Leaves, Seed, Shoots

Leaves and young shoots - raw or cooked. They contain about 1.9% fat, 5.4% pectin, 3.2% sugars, 27.6% cellulose, 1% tannin. Seed - raw or cooked. It is rather small and fiddly to utilize.

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

Temperate regions of the northern hemisphere, including Britain.

TEMPERATE ASIA: Russian Federation-Ciscaucasia (Ciscaucasia), Armenia, Azerbaijan, Georgia, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, Uzbekistan, Russian Federation (Kurile Islands, Primorye, Sakhalin), China (Anhui Sheng, Fujian Sheng, Gansu Sheng, Guangxi Zhuangzu Zizhiqu, Guizhou Sheng, Hebei Sheng, Heilongjiang Sheng, Henan Sheng, Hubei Sheng, Hunan Sheng, Jiangxi Sheng, Jilin Sheng, Liaoning Sheng, Nei Mongol Zizhiqu, Ningxia Huizi Zizhiqu, Qinghai Sheng, Shaanxi Sheng, Shandong Sheng, Shanxi Sheng, Sichuan Sheng, Xinjiang Uygur Zizhiqu, Zhejiang Sheng), Korea, Japan (Hokkaidô, Honshu, Kyushu, Shikoku), Taiwan TROPICAL ASIA: Nepal, Indonesia EUROPE: Russian Federation-European part (European part)

How to Identify

Polygonum persicaria is a ANNUAL growing to 0.6 m (2ft). See above for USDA hardiness. It is hardy to UK zone 5. It is in flower from June to October, and the seeds ripen from August to October. The species is hermaphrodite (has both male and female organs). The plant is self-fertile. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.

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: Seed - sow spring in situ.

Medicinal Uses

Astringent Diuretic Lithontripic Poultice Rubefacient Vermifuge. The leaves are astringent, diuretic, rubefacient and vermifuge. An infusion has been used as a treatment for gravel and stomach pains. A decoction of the plant, mixed with flour, has been used as a poultice to help relieve pain. A decoction of the plant has been used as a foot and leg soak in the treatment of rheumatism. The crushed leaves have been rubbed on poison ivy rash.

Other Uses

DyeA yellow dye is obtained from the plant when alum is used as a mordant.