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Polygonum_aviculare - L.

Common Name Knotweed, Prostrate knotweed
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 Waste places, roadsides, railway embankments and the coast[9]. A common garden weed[1].
Range Throughout Europe, including Britain, to Temperate Asia.
Edibility Rating    (2 of 5)
Other Uses    (0 of 5)
Weed Potential Yes
Medicinal Rating    (3 of 5)
Care
Fully Hardy Moist Soil Semi-shade Full sun
Polygonum_aviculare Knotweed,  Prostrate knotweed


http://commons.wikimedia.org/wiki/File:Polygonum_aviculare_Sturm63.jpg
Polygonum_aviculare Knotweed,  Prostrate knotweed
http://commons.wikimedia.org/wiki/User:Dalgial

 

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Summary


Physical Characteristics

 icon of manicon of flower
Polygonum_aviculare is a ANNUAL growing to 0.3 m (1ft).
It is hardy to zone (UK) 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) and is pollinated by Insects. The plant is self-fertile.
It is noted for attracting wildlife.
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: acid, neutral and basic (alkaline) soils and can grow in very acid soils.
It can grow in semi-shade (light woodland) or no shade. It prefers moist soil. The plant can tolerate maritime exposure.

Synonyms

P. heterophyllum. P. littorale.

Habitats

Edible Uses

Young leaves and plants - raw or cooked[105, 177]. Used as a potherb[183], they are very rich in zinc[179]. A nutritional analysis is available[218]. Seed - raw or cooked. Rather small and fiddly to utilize, they can be used in all the ways that buckwheat (Fagopyrum esculentum) is used, either whole or dried and ground into a powder for use in pancakes, biscuits and piñole[4, 55, 106, 161, 183]. The leaves are a tea substitute[183].

Composition
Figures in grams (g) or miligrams (mg) per 100g of food.
Leaves (Fresh weight)
  • 0 Calories per 100g
  • Water : 81.6%
  • Protein: 1.9g; Fat: 0.3g; Carbohydrate: 10.2g; Fibre: 3.5g; Ash: 3.5g;
  • Minerals - Calcium: 0mg; Phosphorus: 0mg; Iron: 0mg; Magnesium: 0mg; Sodium: 0mg; Potassium: 0mg; Zinc: 0mg;
  • Vitamins - A: 0mg; Thiamine (B1): 0mg; Riboflavin (B2): 0mg; Niacin: 0mg; B6: 0mg; C: 0mg;
  • Reference: [ 218]
  • Notes:

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.



Knotweed is a safe and effective astringent and diuretic herb that is used mainly in the treatment of complaints such as dysentery and haemorrhoids. It is also taken in the treatment of pulmonary complaints because the silicic acid it contains strengthens connective tissue in the lungs[254]. The whole plant is anthelmintic, astringent, cardiotonic, cholagogue, diuretic, febrifuge, haemostatic, lithontripic and vulnerary[4, 7, 9, 21, 53, 147, 172, 176, 178]. It was formerly widely used as an astringent both internally and externally in the treatment of wounds, bleeding, piles and diarrhoea[4]. Its diuretic properties make it useful in removing stones[4]. An alcohol-based preparation has been used with success to treat varicose veins of recent origin[7]. The plant is harvested in the summer and early autumn and is dried for later use[9]. The leaves are anthelmintic, diuretic and emollient[218]. The whole plant is anthelmintic, antiphlogistic and diuretic[218]. The juice of the plant is weakly diuretic, expectorant and vasoconstrictor[218]. Applied externally, it is an excellent remedy to stay bleeding of the nose and to treat sores[4]. The seeds are emetic and purgative[4, 240]. Recent research has shown that the plant is a useful medicine for bacterial dysentery. Of 108 people with this disease, 104 recovered within 5 days when treated internally with a paste of knotweed[254].

Other Uses

Yields a blue dye that is not much inferior to indigo[115]. The part used is not specified, but it is likely to be the leaves. Yellow and green dyes are obtained from the whole plant[168]. The roots contain tannins, but the quantity was not given[223].

Cultivation details

Succeeds in an ordinary garden soil[1] but prefers a moisture retentive not too fertile soil in sun or part shade[200]. Repays generous treatment, in good soils the plant will cover an area up to a metre in diameter[1, 4]. Prefers an acid soil[20]. Dislikes shade. Knotweed is a common and invasive weed of cultivated ground[7]. It is an important food plant for the caterpillars of many species of butterflies[30]. It also produces an abundance of seeds and these are a favourite food for many species of birds[4]. Plants seem to be immune to the predations of rabbits[233]. The flowers have little or no scent or honey and are rarely visited by pollinating insects. Self-fertilization is the usual method of reproduction, though cross-fertilization by insects does sometimes occur[4]. The plant also produces cleistogomous flowers - these never open and therefore are always self-fertilized[4]. The plant is very variable and is seen by most botanists as an aggregate species of 4 very variable species, viz. - P. aviculare. L.; P. boreale. (Lange.)Small.; P. rurivacum. Jord. ex Box.; and P. arenastrum. Box[17].

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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 NameEdibility RatingMedicinal Rating
Polygonum aviculareKnotweed, Prostrate knotweed23

 

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Expert comment

Author

L.

Botanical References

17

Links / References

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Readers comment

J V Cooper   Fri Jul 21 2006

I have read all this information and still have no idea what the plant looks like. A picture would be very good.

Ginger good   Tue Aug 1 2006

Where can I purchase a small amount of Polygonum aviculare to use in a tea?

Jean-Pierre   Fri Dec 29 2006

Very good information. Is it possible to add on your site where we could buy seeds or even the plant for medicinal purpose? Many thanks.

   Nov 29 2010 12:00AM

My friend is of Lebanese origin, and her family has been using Prostrate Knotweed as a salad for generations. It grows as a weed in the garden and they cut it off at ground level, wash it and dry it. Then break it into bite-size pieces. Then add to fresh cut-up tomatoes, oil, vinegar, salt, pepper, and perhaps a little dried mint. Then pick it up with bite-size pieces of Syrian bread or other flat bread and enjoy. Her family calls prostrate knotweed 'farfeen' (sp?)

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