Practical
Plants

Polygonum amphibium

Willow Grass

a perennial member of the Polygonum genus in the family Polygonaceae.

No photo available

Taxonomy and growth

Life cycle
perennial
Height
0.3 m
Fertility
Insects
Flower type
hermaphrodite
Pollinators
Insects

Uses

Toxicity

Toxicity warning. The historical record reports a hazard for this plant. Do not use it to decide which parts are safe to eat or use medicinally.

This section contains historical Plants For A Future notes marked noncommercial.

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[9].

Edible uses

This section contains historical Plants For A Future notes marked noncommercial.

Leaves - raw or cooked. The young shoots are eaten in the spring[10]. Seed - cooked[4]. It is rather small and fiddly to utilize.

Plant part
Leaves
Plant part
Seed

Medicinal uses

Historical medicinal uses. These records describe reported uses. They do not establish safety or effectiveness. Ask a qualified health professional before using any plant medicinally.

This section contains historical Plants For A Future notes marked noncommercial.

The whole plant, but especially the root, is astringent, depurative, skin[1][3][4][7]. An infusion of the leaves and stems has been used to treat stomach pains and children with diarrhoea[10]. The root has been eaten raw, or an infusion of the dried, pounded roots used, in the treatment of chest colds[10]. A poultice of the fresh roots has been applied directly to the mouth to treat blisters[10].

Product or use
Astringent
Product or use
Depurative
Product or use
Pectoral
Product or use
Poultice
Product or use
Skin

Material uses

This section contains historical Plants For A Future notes marked noncommercial.

Tannin is obtained from the plant[1]. No more details, but it is likely to be from the root.

Product or use
Tannin

Environment

Range
Most of Europe, including Britain, temperate Asia, N. America and S. Africa.
Habitat
Lakes, ponds, slow-flowing rivers and canals, also on banks by the river[2][5].
Light
full sun
Shade tolerance
light shade
Water
aquatic
Hardiness
Zone 5+
Soil textures
sandy, loamy, clay
Soil pH
acid, neutral, alkaline
Tolerates Nutritionally Poor Soil
No
Drought
intolerant

Propagation

This section contains historical Plants For A Future notes marked noncommercial.

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

This section contains historical Plants For A Future notes marked noncommercial.

A water or marsh plant growing in water up to 3 metres deep or in boggy soil[5]. This species is hardy to about -25°c[5]. Plants seem to be immune to the predations of rabbits[8]. The leaves are often attacked by the larvae of the water-lily beetle[5]. Plants can either be aquatic with floating ovate-oblong leaf-blades or a leggy marsh plant with lanceolate leaves[5]. Their stems root at the nodes wherever they come into contact with the soil[6].

References

  1. Singh. Dr. G. and Kachroo. Prof. Dr. P. Forest Flora of Srinagar. Bishen Singh Mahendra Pal Singh 1976-00-00

    ↩1↩2

  2. Clapham, Tootin and Warburg. Flora of the British Isles. Cambridge University Press 1962-00-00

    ↩

  3. Schofield. J. J. Discovering Wild Plants - Alaska, W. Canada and the Northwest.

    ↩

  4. Stuart. Rev. G. A. Chinese Materia Medica. Taipei. Southern Materials Centre

    ↩1↩2

  5. Phillips. R. & Rix. M. Perennials Volumes 1 and 2. Pan Books 1991-00-00 ISBN 0-330-30936-9

    ↩1↩2↩3↩4↩5

  6. Huxley. A. The New RHS Dictionary of Gardening. 1992. MacMillan Press 1992-00-00 ISBN 0-333-47494-5

    ↩

  7. Coffey. T. The History and Folklore of North American Wild Flowers. Facts on File. 1993-00-00 ISBN 0-8160-2624-6

    ↩

  8. Thomas. G. S. Perennial Garden Plants J. M. Dent & Sons, London. 1990-00-00 ISBN 0 460 86048 8

    ↩

  9. Bown. D. Encyclopaedia of Herbs and their Uses. Dorling Kindersley, London. 1995-00-00 ISBN 0-7513-020-31

    ↩

  10. Moerman. D. Native American Ethnobotany Timber Press. Oregon. 1998-00-00 ISBN 0-88192-453-9

    ↩1↩2↩3↩4

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