Polygonum plebeiumR.Br.

common knotweed

WFO wfo-0000489163 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h · 8 separate observations

Polygonum plebeium, photographed by chiuluan
fig. a chiuluan, CC BY 4.0 / 2022-05-26 / obs. 200691348
Polygonum plebeium, photographed by chiuluan
fig. b chiuluan, CC BY 4.0 / obs. 187855797
Polygonum plebeium, photographed by 葉子
fig. c 葉子, CC0 1.0 / obs. 185028877
Polygonum plebeium, photographed by Jacy Chen
fig. d Jacy Chen, CC BY 4.0 / obs. 178397266
Polygonum plebeium, photographed by Cheng-Te Hsu
fig. e Cheng-Te Hsu, CC BY 4.0 / obs. 165787582
Polygonum plebeium, photographed by 葉子
fig. f 葉子, CC0 1.0 / obs. 135047652
Polygonum plebeium, photographed by Jacy Chen
fig. g Jacy Chen, CC BY 4.0 / obs. 134094269
Polygonum plebeium, photographed by 葉子
fig. h 葉子, CC0 1.0 / obs. 118895696

Every figure is a research-grade observation under CC0, CC BY or CC BY-SA, rehosted with the photographer’s name, the licence and the observation it came from. Photographs under a NonCommercial licence are excluded from this site and are never stored, which costs us a great many pictures and is not negotiable.

Native range 59 botanical countries

Regions where Polygonum plebeium is native: Angola, Benin, Botswana, Burkina, Cape Provinces, Chad, DR Congo, Egypt, Eritrea, Eswatini, Ethiopia, Free State, KwaZulu-Natal, Madagascar, Malawi, Mali, Mauritania, Mozambique, Namibia, Niger, Nigeria, Northern Provinces, Senegal, Sudan-South Sudan, Tanzania, Zambia, Zimbabwe, China North-Central, China South-Central, China Southeast, Inner Mongolia, Kazakhstan, Korea, Manchuria, Qinghai, Taiwan, Tibet, Andaman Is., Assam, Bangladesh, Cambodia, East Himalaya, India, Jawa, Laos, Myanmar, Nepal, Pakistan, Philippines, Sri Lanka, Thailand, Vietnam, West Himalaya, New South Wales, Northern Territory, Queensland, South Australia, Victoria, Western Australia AngolaBeninBotswanaBurkinaCape ProvincesChadDR CongoEgyptEritreaEswatiniEthiopiaFree StateKwaZulu-NatalMadagascarMalawiMaliMauritaniaMozambiqueNamibiaNigerNigeriaNorthern ProvincesSenegalSudan-South SudanTanzaniaZambiaZimbabweChina North-CentralChina South-CentralChina SoutheastInner MongoliaKazakhstanManchuriaQinghaiTaiwanTibetAssamBangladeshCambodiaEast HimalayaIndiaJawaLaosMyanmarNepalPakistanPhilippinesSri LankaThailandVietnamWest HimalayaNew South WalesNorthern TerritoryQueenslandSouth AustraliaVictoriaWestern Australia KoreaAndaman Is.
Native distribution of Polygonum plebeium, after Kew’s World Checklist of Vascular Plants. Introduced, extinct and doubtful records are excluded, so this is where the plant is from, not everywhere it now grows. Regions too small to draw at this scale are marked with a dot.
RegionTDWG codeContinent
Angola ANG AFRICA
Benin BEN
Botswana BOT
Burkina BKN
Cape Provinces CPP
Chad CHA
DR Congo ZAI
Egypt EGY
Eritrea ERI
Eswatini SWZ
Ethiopia ETH
Free State OFS
KwaZulu-Natal NAT
Madagascar MDG
Malawi MLW
Mali MLI
Mauritania MTN
Mozambique MOZ
Namibia NAM
Niger NGR
Nigeria NGA
Northern Provinces TVL
Senegal SEN
Sudan-South Sudan SUD
Tanzania TAN
Zambia ZAM
Zimbabwe ZIM
Andaman Is. AND ASIA-TROPICAL
Assam ASS
Bangladesh BAN
Cambodia CBD
East Himalaya EHM
India IND
Jawa JAW
Laos LAO
Myanmar MYA
Nepal NEP
Pakistan PAK
Philippines PHI
Sri Lanka SRL
Thailand THA
Vietnam VIE
West Himalaya WHM
China North-Central CHN ASIA-TEMPERATE
China South-Central CHC
China Southeast CHS
Inner Mongolia CHI
Kazakhstan KAZ
Korea KOR
Manchuria CHM
Qinghai CHQ
Taiwan TAI
Tibet CHT
New South Wales NSW AUSTRALASIA
Northern Territory NTA
Queensland QLD
South Australia SOA
Victoria VIC
Western Australia WAU

Region boundaries approximated from Natural Earth (public domain) and mapped to TDWG World Geographical Scheme for Recording Plant Distributions (WGSRPD) level-3 botanical countries (Brummitt 2001). Indicative, not the official WGSRPD geometry.

Flowering 61 in flower of 63 examined

Peak flowering in Jan. Each bar is the share of Polygonum plebeium observations in which someone actually recorded the reproductive state and found the plant in flower, not the raw number of flowering records. That distinction matters: people observe plants far more in spring than in winter, so a bare count of flowering records partly measures when people go outside. Dividing by the number examined removes that. 61 of 63 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 6 months have fewer than 5 examined observations, so no proportion is drawn for them. This is still a global aggregate and not a forecast for your garden: the same species flowers on different dates in different hemispheres. Where a species has fewer than 30 flowering records we do not draw this chart at all. Computed from 10.15468/dl.cgje2x.

Also published as 9 synonyms

A synonym is not an error. It is a record of botanists disagreeing, in print, about where this plant belongs. Each of these was somebody’s considered answer.

  • Avicularia indica Didrichs.
  • Polygonum aviculare var. minutiflorum Franch.
  • Polygonum changii Kitag.
  • Polygonum dryandri Spreng.
  • Polygonum herniarioides Delile
  • Polygonum humifusum var. mandshuricum Skvortsov
  • Polygonum parviflorum Y.L.Chang & S.X.Li
  • Polygonum plebeium subsp. changii (Kitag.) Vorosch.
  • Polygonum roxburghii Meisn.

Sourcesevery claim on this page

  1. World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
  2. iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
  3. Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. Retrieved 2026-07-13.
  4. Kew, World Checklist of Vascular Plants (WCVP v16). native distribution by TDWG level-3 botanical country, and life form. CC BY 3.0. Retrieved 2026-06-04.

We publish what we can source and we say so when we cannot. This page has no care advice and no toxicity claim, because we do not yet have those from a source we can cite.