Polygonum arenastrum
| Polygonum arenastrum | |
| Light: |   |
| Moisture: |  |
| Hardiness: | 5 |
| Soil pH: | 5.6-8.4 |
| Self Pollinated | |
| Height: | 1' |
| Blooms: | Early Summer-Mid Fall |
| Native to: | |
| Shelter | |
| Edible Rating: |  |
| Medicinal Rating: |  |
| Tea: | Yes |
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Polygonum arenastrum (common name: small-leaved knotweed)
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.
Cultivation: Succeeds in an ordinary garden soil[1] but prefers a moisture retentive not too fertile soil in sun or part shade[2]. Repays generous treatment, in good soils the plant will cover an area up to a metre in diameter[1][3]. Prefers an acid soil[4]. Dislikes shade.
Knotweed is a common and invasive weed of cultivated ground[5]. It is an important food plant for the caterpillars of many species of butterflies[6]. It also produces an abundance of seeds and these are a favourite food for many species of birds[3].
Plants seem to be immune to the predations of rabbits[7].
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[3]. The plant also produces cleistogomous flowers - these never open and therefore are always self-fertilized[3].
The plant is very variable according to habitat and is seen by most botanists as part of an aggregate species of 4 very variable species, viz. - P. aviculare. L.; P. boreale. (Lange.)Small.; P. rurivacum. Jord. ex Box.; and P. arenastrum. Bor[8].
Range: Throughout Europe, including Britain.
Habitat: Waste places and roadsides, common throughout Britain[8].
Edibility: Young leaves and plants - raw or cooked[9][10]. Used as a potherb[11], they are very rich in zinc[12]. A nutritional analysis is available[13].
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[3][14][15][16][11].
The leaves are a tea substitute[11].
Medicinal: 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[17].
The whole plant is anthelmintic, astringent, cardiotonic, cholagogue, diuretic, febrifuge, haemostatic, lithontripic and vulnerary[3][5][18][19][20][21][22][23][24]. It was formerly widely used as an astringent both internally and externally in the treatment of wounds, bleeding, piles and diarrhoea[3]. Its diuretic properties make it useful in removing stones[3]. An alcohol-based preparation has been used with success to treat varicose veins of recent origin[5]. The plant is harvested in the summer and early autumn and is dried for later use[18].
The leaves are anthelmintic, diuretic and emollient[13].
The whole plant is anthelmintic, antiphlogistic and diuretic[13].
The juice of the plant is weakly diuretic, expectorant and vasoconstrictor[13]. Applied externally, it is an excellent remedy to stay bleeding of the nose and to treat sores[3].
The seeds are emetic and purgative[3][25].
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[17].
Usage: Yields a blue dye that is not much inferior to indigo[26]. The part used is not specified, but it is likely to be the leaves.
Yellow and green dyes are obtained from the whole plant[27].
The roots contain tannins, but the quantity was not given[28].
Pollinators: Insects, self
Soil: Can grow in light, medium, and heavy soils.
Wind: Tolerates maritime wind exposure
Seed Ripens: Late Summer-Mid Fall
Flower Type: Hermaphrodite
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._x005F
Many species also contain oxalic acid (the distinctive lemony flavour of sorrel) - whil
Also Known As: P. aequale. Lindm. P. littorale. auct. pro parte. P. microspermum. P. calcatum.
Links
References
- ↑ 1.0 1.1 Chittendon, Fred. RHS Dictionary of Plants. Oxford University Press, 1951.
- ↑ Huxley, Anthony. The New Royal Horticultural Society Dictionary of Gardening. MacMillan Press, 1992.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 Grieve, Margaret. A Modern Herbal. Penguin, 1984.
- ↑ Riotte, Louise. Carrots Love Tomatoes. Garden Way, 1978.
- ↑ 5.0 5.1 5.2 Chiej, Roberto. Encyclopaedia of Medicinal Plants. MacDonald, 1984.
- ↑ Carter, David. Butterflies and Moths in Britain and Europe. Pan, 1982.
- ↑ Thomas, Graham. Perennial Garden Plants. J. M. Dent & Sons, 1990.
- ↑ 8.0 8.1 Clapham, Arthur and Tom Tootin, Edmund Warburg. Flora of the British Isles. Cambridge University Press, 1962.
- ↑ Tanaka, Tyōzaburō. Tanaka's Cyclopaedia of Edible Plants of the World. Keigaku Publishing, 1976.
- ↑ Kunkel, Günther. Plants for Human Consumption. Koeltz Scientific Books, 1984.
- ↑ 11.0 11.1 11.2 Facciola, Stephen. Cornucopia - A Source Book of Edible Plants. Kampong Publications, 1990.
- ↑ Read, Bernard. Famine Foods Listed in the Chiu Huang Pen Ts'ao. Taipei Southern Materials Centre, 1977.
- ↑ 13.0 13.1 13.2 13.3 Duke, James and Edward Ayensu. Medicinal Plants of China. Reference Publications, 1985.
- ↑ Harris, Ben. Eat the Weeds. Pivot Health, 1973.
- ↑ Coon, Nelson. The Dictionary of Useful Plants. Rodale Press, 1975.
- ↑ Yanovsky, Elias. Food Plants of the North American Indians Publication 237. US Department of Agriculture.
- ↑ 17.0 17.1 Chevallier, Andrew. The Encyclopedia of Medicinal Plants. Dorling Kindersley, 1996.
- ↑ 18.0 18.1 Launert, Edmund. Edible and Medicinal Plants. Hamlyn, 1981.
- ↑ Lust, John. The Herb Book. Bantam Books, 1983.
- ↑ de Bray, Lys. The Wild Garden.
- ↑ Revolutionary Health Committee of Hunan Province. A Barefoot Doctors Manual. Running Press.
- ↑ Schofield, Janice. Discovering Wild Plants.
- ↑ Yeung, Him-Che. Handbook of Chinese Herbs and Formulas. Institute of Chinese Medicine, 1985.
- ↑ Stuart, George. Chinese Materia Medica. Taipei Southern Materials Centre.
- ↑ Chopra, R. Glossary of Indian Medicinal Plants. Council of Scientific and Industrial Research, New Delhi, 1986.
- ↑ Sowerby, John. The Useful Plants of Great Britain. 1862.
- ↑ Grae, Ida. Nature's Colors. MacMillan Publishing, 1974.
- ↑ Rottsieper, E. Vegetable Tannins. The Forestal Land, 1946.