The common knotgrass or prostrate knotweed (Polygonum aviculare L., 1753) is a herbaceous species belonging to the Polygonaceae family.
From a systematic point of view it belongs to:
P. aviculare species.
The following terms are synonymous:
– Avicularia vulgaris Didr .;
– Centinodia agrestina Fourr .;
– Centinodia avicularis (L.) Fourr .;
– Centinodia humifusa Fourr .;
– Centinodium aviculare (L.) Drejer;
– Polygonum acmophyllum Gand .;
– Polygonum acutifolium Schur;
– Polygonum agrestinum Jord. formerly Boreau;
– Polygonum buxiforme Small;
– Polygonum caballeroi Phil .;
– Polygonum caducifolium Vorosch .;
– Polygonum centinodium Lam .;
– Polygonum chamaechyton P.D.Sell;
– Polygonum chymophyllum Ghent .;
– Polygonum deloynei Gand .;
– Polygonum denudatum Boreau;
– Polygonum dregeanum Meisn .;
– Polygonum erythranthum Gand .:
– Polygonum fallax Small;
– Polygonum floridum (Winterl) Borbás;
– Polygonum franktonii S.J.Wolf & McNeill;
– Polygonum ganderbalense Munshi & Javeid;
– Polygonum geniculatum Poir .;
– Polygonum glaucochloros Gand .;
– Polygonum heterophyllum Lindm .;
– Polygonum hygrogenes Ghent .;
– Polygonum latifolium Giesecke ex Lange;
– Polygonum leptocladum Gand .;
– Polygonum ligerinum Ghent .;
– Polygonum meyenii K. Koch;
– Polygonum monspeliense Thiéb.-Bern. ex Pers .;
– Polygonum myriocladum Gand .;
– Polygonum nanum Bory;
– Polygonum neglectum Besser;
– Polygonum neolittorale P.D.Sell;
– Polygonum nervosum Wallr .;
– Polygonum oedocarpum (Lindm.) P.D.Sell;
– Polygonum oenophyton Gand .;
– Polygonum orogenes Ghent .;
– Polygonum phyllophorum Gand .;
– Polygonum pictaviense Gand .;
– Polygonum pleianthum Gand .;
– Polygonum polycnemiforme (Lecoq & Lamotte) Boreau;
– Polygonum provinciale K. Koch;
– Polygonum rectum (Chrtek) H. Scholz;
– Polygonum rhodanense Gand .;
– Polygonum rubescens Small;
– Polygonum scythicum Klokov;
– Polygonum stricticaule Ghent .;
– Polygonum telonense Ghent ..
Furthermore, within this species, due to its polymorphy, the following subspecies and varieties are recognized, subject to controversy and evaluation by botanists. Below is a list of them:
– Polygonum aviculare L. subsp. aequale Ascherson & Graebner (1913) (synonym = P. avivulare subsp. depressum);
– Polygonum aviculare L. subsp. agrestinum (Jordan ex Boreau) Berher in L. Louis (1887);
– Polygonum aviculare L. subsp. aviculare: it is the most common species;
– Polygonum aviculare L. subsp. bellardii (All.) Bonnier & Layens (1894) (synonym = Polygonum bellardii);
– Polygonum aviculare L. subsp. boreale Lange (synonym = Polygonum boreale): found only in North America;
– Polygonum aviculare L. subsp. buxiforme: typical subspecies of Greenland, Newfoundland and Labrador;
– Polygonum aviculare L. subsp. calcatum (Lindman) Thell. (1913) (synonym = P. aviculare subsp. Depressum);
– Polygonum aviculare L. subsp. depressum (Meisn.) Arcang;
– Polygonum aviculare L. subsp. erectum Schübler & Martens (1834);
– Polygonum aviculare L. subsp. heterophyllum (Lindman) Ascherson & Graebner (1913);
– Polygonum aviculare L. subsp. humifusum (Jordan ex Boreau) Berher in L. Louis (1887);
– Polygonum aviculare L. subsp. littoral (Link) Ball (1878);
– Polygonum aviculare L. subsp. littoral H. Gross (1913);
– Polygonum aviculare L. subsp. microspermum (Jordan ex Boreau) Berher in L. Louis (1887) (synonym = P. aviculare subsp. depressum);
– Polygonum aviculare L. subsp. monspeliense (Pers.) Arcangeli (1882);
– Polygonum aviculare L. subsp. nanum (Bory) Archangels (1882);
– Polygonum aviculare L. subsp. neglectum (Besser) Arcangeli (1882);
– Polygonum aviculare L. subsp. pulchellum (Loisel.) O. Bolòs & Vigo (synonym = Polygonum arenarium subsp. pulchellum);
– Polygonum aviculare L. subsp. rectum Chrtek (1956);
– Polygonum aviculare L. subsp. robertii (Loisel.) O. Bolòs & Vigo (1974) (synonym = Polygonum robertii);
– Polygonum aviculare L. subsp. rurivagum (Jord ex Boreau) Berher – Gracile polygon: this subspecies is actually considered an autonomous species in the majority of classifications;
– Polygonum aviculare L. var. angustissimum Meisn. (synonym = Polygonum bellardii);
– Polygonum aviculare L. var. arenastrum (Jord. Es Boreau) Rouy (synonym = Polygonum arenastrum);
– Polygonum aviculare L. var. bellardii (All.) Duby (1828) (synonym = Polygonum bellardii);
– Polygonum aviculare L. var. calcatum (Lindman) Hylander (1945) (synonym = P. aviculare subsp. depressum);
– Polygonum aviculare L. var. depressum Meisner in DC. (1856) (synonym = P. aviculare subsp. Depressum);
– Polygonum aviculare L. var. erectum (L.) Roth. Former Meisn. (synonym = Polygonum erectum);
– Polygonum aviculare L. var. heterophylum Muschei & Javeid (1986);
– Polygonum aviculare L. var. humifusum (Jordan ex Boreau) Cariot & St-Lager (1889);
– Polygonum aviculare L. var. littorale (Link) Mertens & Koch [(831) (synonym = Polygonum buxiforme);
– Polygonum aviculare L. var. microspermum (Jordan ex Boreau) Cariot & St-Lager (1889) (synonym = P. aviculare subsp. depressum);
– Polygonum aviculare L. var. minimum Murith (1810);
– Polygonum aviculare L. var. monspeliense (Pers.) Ascherson (1866);
– Polygonum aviculare L. var. neglectum (Besser) Nyman (1881);
– Polygonum aviculare L. var. vegetum Ledeb ..
The term Polygonum is the name published by Linnaeus taking it from the Greek πολυγονον polygonon, the name of a plant in Dioscorides, interpreting it as formed by the prefix πολυ- poly- molto, many and by γόνυ gónu knee, knot, referring to the numerous joints of the stem; according to another interpretation it could derive instead from γόνος gónos lineage, progenie, referring to the ease of propagation of plants of this genus.
The sepcific epithet aviculare comes from aviculus uccellino (diminutive of avis bird) as its seeds are eaten by small birds.
Geographic Distribution and Habitat –
The common knotgrass is a plant whose area of origin is not known as it is widespread all over the world and therefore cosmopolitan.
Among other things, the presence of this plant on the globe is very ancient: traces of fossils have been found in the fields of the tertiary sector in Europe (a period of time ranging from 65 million years ago to today). Other classifications try to define the chorological type more specifically by defining it as Eurasian.
In Italy it is present throughout the territory (missing in alluvial plains such as the Po Valley), as well as it is common throughout Europe and the rest of the world.
Its typical habitat is the edges of paths or roads, trampled and man-made areas, but also ditches and rubble areas or fields, crops and uncultivated fields. It tolerates drought well and also grows in compact and hard soils. The substrate for this plant is both calcareous and siliceous, with neutral pH but in need of soils with good nutritional levels and grows in a vegetation belt from the plain up to 1800 – 2000 m a.s.l.
Polygonum aviculare is an annual herb, with two main forms, with a semi-erect stem that can grow from 10 to 40 cm in height but often with a creeping trend.
The leaves are glabrous and petiolate, elongated-elliptical with short stems and rounded bases; the upper ones are few and are linear and stemless. The stipules are fused into a translucent sheath enclosing the stem, known as ocher, which is membranous and silvery. The flowers are regular, green with white or pink margins. Each has five perianth segments, superimposed at the base, with five to eight stamens and three fused carpels.
The fruit is a walnut (diclesium) formed by the persistent perianth, with ribbed and imbricated lobes of 2.5-3 mm, which completely or partially envelops the pyriform achenium, trine, of 2-3 mm, with the 3 concave faces, pointed at the apex and rounded at the base, shiny, dark reddish-brown.
Polygonum aviculare is an annual plant that is harvested in nature for local use as a food, medicine, and source of materials.
It is a very cold hardy plant, able to tolerate temperatures down to around -25 ° C when in a dormant state.
It grows in many substrates but prefers a soil that is not too fertile, preferably tending to an acid pH, which retains humidity, in a sunny position or in partial shade.
In general it is a common and invasive herb of cultivated land as it produces an abundance of favorite seeds for many bird species.
Propagation occurs by seed, with sowing in spring in an unheated seedbed.
Germination is generally abundant and the seedlings, as soon as they are manageable, should be placed in individual pots and transplanted in late spring.
It can also propagate by division both in spring and in autumn.
Customs and Traditions –
Common knotgrass is a highly variable plant depending on habitat and also contains oxalic acid which, although not toxic, this substance can bind other minerals making them unavailable to the body and leading to a mineral deficiency. That said, if it must be consumed for food use, it is better to cook it to reduce the oxalic acid content. People with a tendency to rheumatism, arthritis, gout, kidney stones or hyperacidity should be especially careful if they include this plant in their diet as it can aggravate their condition. It also contains a lot of zinc.
For edible use, in fact, the leaves and young plants, both raw and cooked, are used.
The seeds can be eaten both raw and cooked; they are quite small and impractical to use, they can be used in all ways buckwheat (Fagopyrum esculentum Moench, 1794) is used, both whole and dried and ground into powder for use in pancakes, biscuits and other products .
The leaves are also a substitute for tea.
In medicinal use, Polygonum aviculare is a safe and effective astringent and diuretic herb that is mainly used in the treatment of ailments such as dysentery and hemorrhoids. It is also taken to treat lung ailments because the silicic acid it contains strengthens the connective tissue of the lungs.
The whole plant is anthelmintic, antiphlogistic, astringent, cardiotonic, cholagogue, diuretic, febrifuge, hemostatic, lithotriptic and vulnerary.
In the past it was widely used as an astringent both internally and externally in the treatment of wounds, bleeding, hemorrhoids and diarrhea.
Its diuretic properties make it useful in removing stones.
An alcohol-based preparation has been used successfully to treat varicose veins of recent origin.
The leaves are anti-helminthic, diuretic and emollient.
The juice of the plant is weakly diuretic, expectorant and vasoconstrictor; applied externally, it is an excellent remedy for stopping nose bleeding and for treating sores.
The seeds are emetic and purgative.
Recent research has shown that the plant is a useful medicine for bacterial dysentery. Of the 108 people with this disease, 104 recovered within 5 days when they were treated internally with a Polygonum aviculare paste.
Among other uses, it should be remembered that a blue dye is extracted from this plant which is not much inferior to indigo.
The part used is not specified, but it is likely the leaves.
On the other hand, yellow and green dyes are obtained from the whole plant.
The roots contain tannins, but the amount is unknown.
The substances contained in this plant are: tannins (thiamin), silicic acid, oxalic acid, various mucilages and flavonoids (riboflavin); in addition there are the flavonols avicularin, myricitrin and juglanin. Astragalin and betmidine flavonoids and avicolin lignan were also found. Another known component is the diterpene alkaloid panicudin.
Finally it is emphasized that, although no specific mention has been made for this species, it has been reported that some plants of this genus can cause photosensitivity in sensitive people.
Preparation Method –
The common knotgrass is a plant that is harvested in summer and early autumn and is dried for later use.
The edible parts of this plant are the leaves and seeds as they contain a floury egg white. With the leaves you can prepare infusions for various therapeutic uses.
– Acta Plantarum – Flora of the Italian Regions.
– Wikipedia, the free encyclopedia.
– Useful Tropical Plants Database.
– Conti F., Abbate G., Alessandrini A., Blasi C. (ed.), 2005. An annotated checklist of the Italian vascular flora, Palombi Editore.
– Pignatti S., 1982. Flora of Italy, Edagricole, Bologna.
– Treben M., 2000. Health from the Lord’s Pharmacy, Advice and experiences with medicinal herbs, Ennsthaler Editore.
Warning: Pharmaceutical applications and alimurgical uses are indicated for informational purposes only, they do not represent in any way a medical prescription; therefore no responsibility is taken for their use for curative, aesthetic or food purposes.