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Persicaria amphibia - L.

Common Name Willow Grass, Water knotweed, Longroot smartweed, Water smartweed
Family Polygonaceae
USDA hardiness 4-8
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].
Habitats Lakes, ponds, slow-flowing rivers and canals, also on banks by the river[17, 187].
Range Most of Europe, including Britain, temperate Asia, N. America and S. Africa.
Edibility Rating    (1 of 5)
Other Uses    (1 of 5)
Weed Potential Yes
Medicinal Rating    (2 of 5)
Care (info)
Fully Hardy Wet Soil Water Plants Semi-shade Full sun
Persicaria amphibia Willow Grass, Water knotweed, Longroot smartweed,  Water smartweed


http://commons.wikimedia.org/wiki/File:Persicaria_amphibia_Sturm62.jpg
Persicaria amphibia Willow Grass, Water knotweed, Longroot smartweed,  Water smartweed
http://commons.wikimedia.org/wiki/User:Pethan

 

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Summary


Physical Characteristics

 icon of manicon of flower
Persicaria amphibia is a PERENNIAL growing to 0.3 m (1ft).
See above for USDA hardiness. It is hardy to UK zone 5. It is in flower from July to September. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects.
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 wet soil and can grow in water.

UK Hardiness Map US Hardiness Map

Synonyms

Persicaria amphibia.

Habitats

Edible Uses

Leaves - raw or cooked. The young shoots are eaten in the spring[257]. Seed - cooked[178]. It is rather small and fiddly to utilize.

References   More on Edible Uses

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.


The whole plant, but especially the root, is astringent, depurative, skin[145, 172, 178, 207]. An infusion of the leaves and stems has been used to treat stomach pains and children with diarrhoea[257]. The root has been eaten raw, or an infusion of the dried, pounded roots used, in the treatment of chest colds[257]. A poultice of the fresh roots has been applied directly to the mouth to treat blisters[257].

References   More on Medicinal Uses

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Other Uses

Tannin is obtained from the plant[145]. No more details, but it is likely to be from the root.

Special Uses

References   More on Other Uses

Cultivation details

A water or marsh plant growing in water up to 3 metres deep or in boggy soil[187]. This species is hardy to about -25°c[187]. Plants seem to be immune to the predations of rabbits[233]. The leaves are often attacked by the larvae of the water-lily beetle[187]. Plants can either be aquatic with floating ovate-oblong leaf-blades or a leggy marsh plant with lanceolate leaves[187]. Their stems root at the nodes wherever they come into contact with the soil[200].

References   Carbon Farming Information and Carbon Sequestration Information

Temperature Converter

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Propagation

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.

Other Names

If available other names are mentioned here

Found In

Countries where the plant has been found are listed here if the information is available

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it’s worth checking.

Conservation Status

IUCN Red List of Threatened Plants Status :

Related Plants
Latin NameCommon NameHabitHeightHardinessGrowthSoilShadeMoistureEdibleMedicinalOther
Persicaria odorataVietnamese coriander, Asian mintPerennial0.2 9-11 FLMHSNMWe322
Polygonum persicariaRed Leg, Spotted ladysthumbAnnual0.6 4-8  LMHSNM121

Growth: S = slow M = medium F = fast. Soil: L = light (sandy) M = medium H = heavy (clay). pH: A = acid N = neutral B = basic (alkaline). Shade: F = full shade S = semi-shade N = no shade. Moisture: D = dry M = Moist We = wet Wa = water.

 

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Author

L.

Botanical References

17200

Links / References

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