Joint Weed

Polygonum barbatum

Physical Characteristics

Polygonum barbatum is a PERENNIAL growing to 0.8 m (2ft 6in). It is in flower from August to September, and the seeds ripen from September to October. The species is hermaphrodite (has both male and female organs). 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.

Distribution

E. Asia - Himalayas to western and southern China

Habitats

Woodland Garden Sunny Edge; Dappled Shade; Shady Edge;

Edible Uses

Edible Parts: Leaves Shoots Edible Uses: Tender young leaves and shoots - cooked as a vegetable[177, 272]. They have a somewhat pungent flavour[178].

Medicinal Uses

Astringent Carminative Parasiticide The seeds are used to relieve the griping pains of colic[240]. The root is astringent and cooling[240]. A paste of the root is used externally in the treatment of scabies[272].

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[238].