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<big>''[[Polygonum aviculare]]'' L.</big>
__NOTOC__
:Protologue: Sp. pl. 1: 362 (1753).
:Chromosome number: 2''n''= 20 (22), 40, 60
Polygonum aviculare L. - 1, flowering stem; 2, dissected flower; 3, inflorescence; 4, fruit
== Vernacular names ==
*Knot grass, prostrate knot weed, wire weed (En). *Renouée des oiseaux (Fr)
*Vietnam: biền súc, rau dắng.
''P. aviculare'' is mainly locally used. In Vietnam and Malesia, the dried plant is found in Chinese pharmacies.
== Properties ==
Pharmacological effects of ''P. aviculare'' extracts include lowering of blood pressure in cats, rabbits and dogs, an anticoagulant activity on sheep-blood by aqueous and alcohol extracts, and anti-inflammatory and hepato-protective activity. In mice, the aqueous extract showed immunomodulatory effects by stimulation of the production of anti-sheep red blood cells (IgG) antibodies.
The alcohol extract is moderately active in vitro against fungi causing leaf-spot disease in potato: ''Alternaria alternata'' , ''A. solani'' , ''Cladosporium herbarum'' , ''Colletotrichum coccodes'' , ''Phytophthora infestans'' and ''Verticillium lycopersici'' . The alcohol extract of the aerial parts exhibited insect repellent and insecticidal activities.
Finally, ''P. aviculare'' has been found to be phytotoxic in the United States and Australia, where it shows allelopathic activity in crop, pasture and weed species.
== Description ==
*An annual, very variable, procumbent or ascending herb, 10-80 cm tall; stems much branched, grooved, glabrous. *Leaves alternate, simple, oblanceolate to elliptical, 0.7-1.5 cm × 0.2-0.5 cm, base cuneate, apex acuminate to acute, both surfaces glabrous, papillose, subsessile, ocrea 2-5 mm long, glabrous, conspicuously veined, upper margin lacerate. *Inflorescence an axillary, 3-6-flowered fascicle, often hidden in ocrea, bracts lacerate, glabrous. *Flowers with short, jointed pedicel, actinomorphic, bisexual, small, perianth segments 5, elliptical, 2-3 mm long, apex acute, 1 main vein per tepal, sometimes branched, white to pink; stamens 8, filaments flattened, base swollen, dilated, anthers ovate, small; interstaminal nectaries absent; ovary superior, 1-ovulate, styles 3-partite. *Fruit a trigonous nutlet, 2-3 mm long, puncticulate, dark brown, dull. *Seedling with epigeal germination.
== Growth and development ==
''P. aviculare'' can be found flowering and fruiting throughout the year when enough water is available. The flavonoid content is highest at the start of flowering. Self-pollination in the open flower is the main pollination type. If this fails, pollination occurs as the perianth is closing. The flowers stay open for 1-5 days. Self-pollination in flower buds mainly takes place after a week of hot, sunny weather. Outbreeding seems to be extremely rare, and emasculation in flower buds precluds fruit formation.
== Other botanical information ==
''Polygonum'' s.l. has been a major challenge for taxonomists since Linnaeus established the genus as a large and loosely knit unit. After a major revision, 2 tribes within subfamily ''Polygonoideae'' were established. Tribe ''Persicarieae'' comprises the large genus ''Persicaria'' Miller, in which 4 sections are recognized, and 3 more small genera. Tribe ''Polygoneae'' comprises ''Polygonum'' , with about 20 species, and 6 small genera, one of which is ''Fallopia'' . In ''Polygonum'' , two sections are distinguished, ''Polygonum'' and ''Tephis'' , although their boundaries are not clear due to the high level of variability within the genus.
''P. aviculare'' is a successful weedy species complex, due to the genetic polymorphism it shows, as well as the ploidy levels, and high phenotypic plasticity.
== Propagation and planting ==
''P. aviculare'' is a noxious weed in temperate regions because it germinates rapidly in spring and seeds may remain viable for up to 60 years. Emergence of seedlings declines with increasing depth of burial. The germination rate decreases at temperatures higher than 15C 15 °C and under saline conditions. The salinity induced dormancy is alleviated by gibberellic acid.
== Harvesting ==
== Genetic resources and breeding ==
''P. aviculare'' is a widespread weed with large genetic variation, and thus does not seem to be liable to genetic erosion. No substantial germplasm collections exist for ''P. aviculare'' .
== Prospects ==
== Literature ==
* Khan, M.A. & Ungar, I.A., 1998. Seed germination and dormancy of Polygonum aviculare L. as influenced by salinity, temperature and giberellic acid. Seed Science and Technology 26(1): 107-117.
== Other selected sources ==
*[63] Arias,R.J., Schmeda-Hirschmann, G. & Falcao, A., 1992. Feeding deterency and insecticidal effects of plant extracts on Lutzomyia longipalpis. Phytotherapy Research 6(2): 64—67.* [215] Council of Scientific and Industrial Research, 1948-19761948—1976. The wealth of India: a dictionary of Indian raw materials & industrial products. 11 volumes. Publications and Information Directorate, New Delhi, India.*[273] Duke, J.A., 1985. Handbook of medicinal herbs. CRC Press, Inc., Boca Raton, Florida, United States. 677 pp.*[455] Huang, T.-C. (Editor), 1993—. Flora of Taiwan. 2nd Edition. Editorial Committee of the Flora of Taiwan, Taipei, Taiwan, Republic of China.*[786] Perry, L.M., 1980. Medicinal plants of East and Southeast Asia. Attributed properties and uses. MIT Press, Cambridge, Massachusetts, United States & London, United Kingdom. 620 pp.*[788] Pételot, A., 1952—1954. Les plantes médicinales du Cambodge, du Laos et du Vietnam [The medicinal plants of Cambodia, Laos and Vietnam]. 4 volumes. Centre National de Recherches Scientifiques et Techniques, Saigon, Vietnam.*[967] Strzelecka, H., Glinkowska, G., Skopinska-Rozewska, E., Malkowska-Zwiers, W., Sikorska, E. & Sokolnicka, I., 1995. Immunotropic activity of plant extracts. I. Influence of water extracts of chosen crude drugs on humoral and cellular immune response. Herba Polonica 41(1): 23—32.(in Polish)
== Authors ==
*Rina R.P. Irwanto