Trapa natansL.

Jesuit's nutWater ChestnutWater caltropwater chestnut

WFO wfo-0000458183 Accepted WFO 2026-06 8 photographs CC0 / CC BY / CC BY-SA

Plate 1 figs. a–h · 8 separate observations

Trapa natans, photographed by Bonnie Semmling
fig. a Bonnie Semmling, CC BY 4.0 / 2022-03-10 / obs. 182387861
Trapa natans, photographed by Taro Ietaka
fig. b Taro Ietaka, CC BY 4.0 / obs. 161979508
Trapa natans, photographed by Grzegorz Grzejszczak
fig. c Grzegorz Grzejszczak, CC BY-SA 4.0 / obs. 160099087
Trapa natans, photographed by Oleksii Vasyliuk
fig. d Oleksii Vasyliuk, CC BY 4.0 / obs. 159963482
Trapa natans, photographed by Eva Grabsch
fig. e Eva Grabsch, CC0 1.0 / obs. 159423511
Trapa natans, photographed by Olena V. Vakarenko
fig. f Olena V. Vakarenko, CC BY 4.0 / obs. 171332881
Trapa natans, photographed by Olena V. Vakarenko
fig. g Olena V. Vakarenko, CC BY 4.0 / obs. 171333908
Trapa natans, photographed by Grzegorz Grzejszczak
fig. h Grzegorz Grzejszczak, CC BY-SA 4.0 / obs. 186744218

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 87 botanical countries

Regions where Trapa natans is native: Algeria, Angola, Botswana, Burkina, Cameroon, Central African Republic, Chad, Congo, DR Congo, Gabon, Gambia, Guinea-Bissau, Kenya, KwaZulu-Natal, Malawi, Mozambique, Namibia, Nigeria, Sudan-South Sudan, Tanzania, Tunisia, Uganda, Zambia, Zimbabwe, Altay, Amur, Buryatiya, China North-Central, China South-Central, China Southeast, Chita, Hainan, Inner Mongolia, Iran, Irkutsk, Japan, Kazakhstan, Khabarovsk, Korea, Krasnoyarsk, Manchuria, North Caucasus, Primorye, Taiwan, Tibet, Transcaucasus, West Siberia, Xinjiang, Assam, Bangladesh, Cambodia, East Himalaya, India, Jawa, Laos, Myanmar, Nepal, Pakistan, Philippines, Sri Lanka, Sumatera, Thailand, Vietnam, West Himalaya, Albania, Austria, Baleares, Baltic States, Belarus, Bulgaria, Central European Russia, Czechia-Slovakia, East European Russia, France, Germany, Greece, Hungary, Italy, Krym, Northwest European Russia, NW. Balkan Pen., Poland, Romania, South European Russia, Switzerland, Türkiye-in-Europe, Ukraine AlgeriaAngolaBotswanaBurkinaCameroonCentral African RepublicChadCongoDR CongoGabonGambiaGuinea-BissauKenyaKwaZulu-NatalMalawiMozambiqueNamibiaNigeriaSudan-South SudanTanzaniaTunisiaUgandaZambiaZimbabweAltayAmurBuryatiyaChina North-CentralChina South-CentralChina SoutheastChitaHainanInner MongoliaIranIrkutskJapanKazakhstanKhabarovskKrasnoyarskManchuriaNorth CaucasusPrimoryeTaiwanTibetTranscaucasusWest SiberiaXinjiangAssamBangladeshCambodiaEast HimalayaIndiaJawaLaosMyanmarNepalPakistanPhilippinesSri LankaSumateraThailandVietnamWest HimalayaAlbaniaAustriaBaltic StatesBelarusBulgariaCentral European RussiaCzechia-SlovakiaEast European RussiaFranceGermanyGreeceHungaryItalyKrymNorthwest European RussiaNW. Balkan Pen.PolandRomaniaSouth European RussiaSwitzerlandTürkiye-in-EuropeUkraine KoreaBaleares
Native distribution of Trapa natans, 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
Algeria ALG AFRICA
Angola ANG
Botswana BOT
Burkina BKN
Cameroon CMN
Central African Republic CAF
Chad CHA
Congo CON
DR Congo ZAI
Gabon GAB
Gambia GAM
Guinea-Bissau GNB
Kenya KEN
KwaZulu-Natal NAT
Malawi MLW
Mozambique MOZ
Namibia NAM
Nigeria NGA
Sudan-South Sudan SUD
Tanzania TAN
Tunisia TUN
Uganda UGA
Zambia ZAM
Zimbabwe ZIM
Altay ALT ASIA-TEMPERATE
Amur AMU
Buryatiya BRY
China North-Central CHN
China South-Central CHC
China Southeast CHS
Chita CTA
Hainan CHH
Inner Mongolia CHI
Iran IRN
Irkutsk IRK
Japan JAP
Kazakhstan KAZ
Khabarovsk KHA
Korea KOR
Krasnoyarsk KRA
Manchuria CHM
North Caucasus NCS
Primorye PRM
Taiwan TAI
Tibet CHT
Transcaucasus TCS
West Siberia WSB
Xinjiang CHX
Albania ALB EUROPE
Austria AUT
Baleares BAL
Baltic States BLT
Belarus BLR
Bulgaria BUL
Central European Russia RUC
Czechia-Slovakia CZE
East European Russia RUE
France FRA
Germany GER
Greece GRC
Hungary HUN
Italy ITA
Krym KRY
Northwest European Russia RUW
NW. Balkan Pen. YUG
Poland POL
Romania ROM
South European Russia RUS
Switzerland SWI
Türkiye-in-Europe TUE
Ukraine UKR
Assam ASS ASIA-TROPICAL
Bangladesh BAN
Cambodia CBD
East Himalaya EHM
India IND
Jawa JAW
Laos LAO
Myanmar MYA
Nepal NEP
Pakistan PAK
Philippines PHI
Sri Lanka SRL
Sumatera SUM
Thailand THA
Vietnam VIE
West Himalaya WHM

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 41 in flower of 408 examined

Peak flowering in Aug. Each bar is the share of Trapa natans 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. 41 of 408 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 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 195 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.

  • Trapa acicularis V.N.Vassil.
  • Trapa acornis Nakano
  • Trapa alatyrica Sprygin ex V.N.Vassil.
  • Trapa algeriensis V.N.Vassil.
  • Trapa amurensis Flerow
  • Trapa amurensis var. bispinosa Flerow
  • Trapa amurensis var. komarovii Skvortsov
  • Trapa annosa Janković
  • Trapa annosa f. bicornis Janković
  • Trapa annosa f. erecticornis Janković
  • Trapa annosa f. pseudomuzzanensis Janković
  • Trapa araborum V.N.Vassil.
  • Trapa arcuata S.H.Li & Y.L.Chang
  • Trapa astrachanica (Flerow) N.A.Winter
  • Trapa astrachanica var. caspica (V.N.Vassil.) Tzvelev
  • Trapa austroafricana V.N.Vassil.
  • Trapa bicornis Osbeck
  • Trapa bicornis var. acornis (Nakano) Z.T.Xiong
  • Trapa bicornis var. bispinosa (Roxb.) Nakano
  • Trapa bicornis var. cochinchinensis (Lour.) Steenis
  • Trapa bicornis var. iwasakii Nakano
  • Trapa bicornis var. jinumae (Nakano) Nakano
  • Trapa bicornis var. makinosa (Nakano) Nakano
  • Trapa bicornis var. quadrispinosa (Roxb.) Z.T.Xiong

and 171 more.

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.