Herb: Willow Grass

Latin name: Polygonum amphibium

Synonyms: Persicaria amphibia

Family: Polygonaceae (Buckwheat Family)

Medicinal use of Willow Grass:

The whole plant, but especially the root, is astringent, depurative, skin. An infusion of the leaves and stems has been used to treat stomach pains and children with diarrhoea. The root has been eaten raw, or an infusion of the dried, pounded roots used, in the treatment of chest colds. A poultice of the fresh roots has been applied directly to the mouth to treat blisters.

Description of the plant:


30 cm
(11 3/4 inch)

July to

Habitat of the herb:

Lakes, ponds, slow-flowing rivers and canals, also on banks by the river.

Edible parts of Willow Grass:

Leaves - raw or cooked. The young shoots are eaten in the spring. Seed - cooked. It is rather small and fiddly to utilize.

Other uses of the herb:

Tannin is obtained from the plant. No more details, but it is likely to be from the root.

Propagation of Willow Grass:

Seed - sow spring in a cold frame. Germination is usually free and easy. When they are large enough to handle, prick the seedlings out into individual pots and plant them out in the summer if they have reached sufficient size. If not, overwinter them in a cold frame and plant them out the following spring after the last expected frosts. Division in spring or autumn. Very easy, larger divisions can be planted out direct into their permanent positions. We have found that it is better to pot up the smaller divisions and grow them on in light shade in a cold frame until they are well established before planting them out in late spring or early summer.

Cultivation of the herb:

Lakes, ponds, slow-flowing rivers and canals, also on banks by the river.

Known hazards of Polygonum amphibium:

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.

Plant information taken from the Plants For A Future.