Polygonum aviculare or common knotgrass is a plant related to
buckwheat and
dock. It is also called prostrate knotweed, birdweed, pigweed and lowgrass. It is an annual found in fields and wasteland, with white flowers from June to October. It is widespread across many countries in temperate regions, apparently native to Eurasia, naturalized in temperate parts of the Southern Hemisphere.[2][3][4][5][6][7]
Description
Common knotgrass is an annual herb with a semi-erect stem that may grow from 10 to 40 cm (4 to 16 in) high. The leaves are hairless and short-stalked. They are longish-elliptical with short stalks and rounded bases; the upper ones are few and are linear and stalkless. The
stipules are fused into a stem-enclosing, translucent sheath known as an
ochrea that is membranous and silvery. The flowers are regular, green with white or pink margins. Each has five
perianth segments, overlapping at the base, five to eight stamens and three fused carpels. The fruit is a dark brown, three-edged nut. The seeds need light to germinate which is why this plant appears in disturbed soil in locations where its seeds may have lain dormant for years. It is a common carrier of the parasitic pathogen powdery mildew,[8] which can give the leaves a whitish appearance.[3][9]
Subspecies
Polygonum aviculare has a wide distribution as an arable weed and plant of fields, shingle, sand, roadsides, yards and waste places. There is much morphological variation among different populations and several different sub-species are recognized:[1][2][3][9]
Polygonum aviculare subsp. aviculare – very widespread
It formed a traditional ingredient in porridge consumed by Germanic peoples of western Europe, and has been found in numerous autopsies of peat bodies, including the
Tollund Man.
In Vietnam, where it is called rau đắng, it is widely used to prepare soup and hot pot, particularly in the southern region.
^Gibbs Russell, G. E., W. G. M. Welman, E. Retief, K. L. Immelman, G. Germishuizen, B. J. Pienaar, M. Van Wyk & A. Nicholas. 1987. List of species of southern African plants. Memoirs of the Botanical Survey of South Africa 2(1–2): 1–152(pt. 1), 1–270(pt. 2).
^https://www.researchgate.net/publication/338187775 Parasitic activity of powdery mildew (pathogen strain hmlac226) on prostrate knotweed (polygonum aviculare l.) at various locations of Shenyang, northeast China , Iqbal, M. F., Fend, Y. L., Liu, M. C., Lu, X. R., Nasir, M., Sikandar, A., 2019
^
abClapham, A.R. , Tutin, T.G. and Warburg, E.F. 1968. Excursion Flora of the British Isles. Cambridge Press.
ISBN0-521-04656-4
^
abParnell, J. and Curtis, T. 2012. Webb's An Irish Flora. Cork University Press.
ISBN978-185918-4783
^"Knotgrass". Planteværn Online. Aarhus University. Retrieved 1 February 2016.
^Xu, Fuquan; Guan, Huashi; Li, Guoqiang; Liu, Hongbing (2009). "LC Method for Analysis of Three Flavonols in Rat Plasma and Urine after Oral Administration of Polygonum aviculare Extract". Chromatographia. 69 (11–12): 1251–1258.
doi:
10.1365/s10337-009-1088-x.
S2CID93888073.
^Kim, Hyoung Ja; Woo, Eun-Rhan; Park, Hokoon (1994). "A Novel Lignan and Flavonoids from Polygonum aviculare". Journal of Natural Products. 57 (5): 581–586.
doi:
10.1021/np50107a003.
^Łańcucka-Środoniowa M.: Macroscopic plant remains from the freshwater Miocene of the Nowy Sącz Basin (West Carpathians, Poland) [Szczątki makroskopowe roślin z miocenu słodkowodnego Kotliny Sądeckiej (Karpaty Zachodnie, Polska)]. Acta Palaeobotanica 1979 20 (1): 3-117.