Helosciadium nodiflorum(L.) W.D.J.Koch

European marshwort

WFO wfo-0000719285 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h · 8 separate observations

Helosciadium nodiflorum, photographed by David Delon
fig. a David Delon, CC BY 4.0 / 2022-05-19 / obs. 198909201

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 47 botanical countries

Regions where Helosciadium nodiflorum is native: Algeria, Azores, Canary Is., Chad, Egypt, Eritrea, Ethiopia, Libya, Madeira, Morocco, Somalia, Tanzania, Tunisia, Afghanistan, Cyprus, East Aegean Is., Iran, Iraq, Kazakhstan, Kirgizstan, Lebanon-Syria, Palestine, Saudi Arabia, Tadzhikistan, Türkiye, Turkmenistan, Uzbekistan, Yemen, Pakistan, Albania, Baleares, Belgium, Bulgaria, Corse, France, Germany, Great Britain, Ireland, Italy, Netherlands, Poland, Portugal, Sardegna, Sicilia, Spain, Switzerland, Türkiye-in-Europe AlgeriaChadEgyptEritreaEthiopiaLibyaMoroccoSomaliaTanzaniaTunisiaAfghanistanCyprusEast Aegean Is.IranIraqKazakhstanKirgizstanLebanon-SyriaPalestineSaudi ArabiaTadzhikistanTürkiyeTurkmenistanUzbekistanYemenPakistanAlbaniaBelgiumBulgariaCorseFranceGermanyIrelandItalyNetherlandsPolandPortugalSiciliaSpainSwitzerlandTürkiye-in-Europe AzoresCanary Is.MadeiraBalearesSardegna
Native distribution of Helosciadium nodiflorum, 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
Albania ALB EUROPE
Baleares BAL
Belgium BGM
Bulgaria BUL
Corse COR
France FRA
Germany GER
Great Britain GRB
Ireland IRE
Italy ITA
Netherlands NET
Poland POL
Portugal POR
Sardegna SAR
Sicilia SIC
Spain SPA
Switzerland SWI
Türkiye-in-Europe TUE
Afghanistan AFG ASIA-TEMPERATE
Cyprus CYP
East Aegean Is. EAI
Iran IRN
Iraq IRQ
Kazakhstan KAZ
Kirgizstan KGZ
Lebanon-Syria LBS
Palestine PAL
Saudi Arabia SAU
Tadzhikistan TZK
Türkiye TUR
Turkmenistan TKM
Uzbekistan UZB
Yemen YEM
Algeria ALG AFRICA
Azores AZO
Canary Is. CNY
Chad CHA
Egypt EGY
Eritrea ERI
Ethiopia ETH
Libya LBY
Madeira MDR
Morocco MOR
Somalia SOM
Tanzania TAN
Tunisia TUN
Pakistan PAK ASIA-TROPICAL

Not drawn on the map: Great Britain. We hold no public-domain boundary for this region, so it is listed rather than guessed at.

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 239 in flower of 389 examined

Proportion of examined Helosciadium nodiflorum in flower, by month
Month In flower Examined Share 95% interval
Jan 54 71 76% 65% to 84%
Feb 13 27 48% 31% to 66%
Mar 8 21 38% 21% to 59%
Apr 9 29 31% 17% to 49%
May 16 22 73% 52% to 87%
Jun 17 30 57% 39% to 73%
Jul 34 39 87% 73% to 94%
Aug 2 21 10% 3% to 29%
Sep 1 14 7% 1% to 31%
Oct 4 26 15% 6% to 34%
Nov 15 22 68% 47% to 84%
Dec 66 67 99% 92% to 100%

Peak flowering in Dec. Each bar is the share of Helosciadium nodiflorum 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. 239 of 389 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.

Where it actually grows measured, from 1,973 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low 0.1 °C 4.8 °C 11.3 °C
Warmest month, mean daily high 17.5 °C 21.4 °C 30.3 °C
Annual rainfall 546 mm 955 mm 1,669 mm
Rainfall in the driest quarter 17 mm 162 mm 273 mm

It is found where winters are cool but frost is light or absent. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 1,973 research-grade observations of Helosciadium nodiflorum that carry a coordinate, and this is the range those places actually span. The 5th and 95th percentiles are used rather than the minimum and maximum, because a single cultivated specimen in a heated conservatory should not widen a tropical plant's range to the Arctic.

This is not a hardiness zone. A USDA zone is the average annual extreme minimum temperature. The figure above is the mean daily minimum of the coldest month, which is a different quantity and is typically far warmer. Reading one as the other would place a plant several zones too warm, so we do not publish a hardiness zone, because we do not have one. Climate from CHELSA V2.1 (Karger et al. 2017); occurrences from 10.15468/dl.cgje2x.

Also published as 34 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.

  • Apium nodiflorum (L.) Lag.
  • Apium nodiflorum subsp. mairei Molina Abril & Sard.Rosc.
  • Apium nodiflorum var. giganteum (Duby) T.Durand
  • Apium nodiflorum var. intermedium (Coss. & Germ.) T.Durand
  • Apium nodiflorum var. minus (Candargy) T.Durand
  • Apium nodiflorum var. ochreatum (DC.) Lange
  • Apium nodiflorum var. ocreatum Bab.
  • Cicuta nodiflora (L.) Crantz
  • Helodium nodiflorum (L.) Dumort.
  • Helosciadium augustini Sennen
  • Helosciadium hybridum Mérat ex F.W.Schultz
  • Helosciadium intermedium Ten. ex Nyman
  • Helosciadium muratianum Maire
  • Helosciadium nodiflorum f. purpurascens Maire
  • Helosciadium nodiflorum var. giganteum Duby
  • Helosciadium nodiflorum var. intermedium Coss. & Germ.
  • Helosciadium nodiflorum var. minus Candargy
  • Helosciadium nodiflorum var. ochreatum (DC.) DC.
  • Helosciadium nodiflorum var. radiatum (Viv.) Coss.
  • Helosciadium nodiflorum var. repentiforme Rouy & E.G.Camus
  • Helosciadium stoloniferum Nyman
  • Lavera nodiflora (L.) Raf.
  • Meum nodiflorum (L.) Baill.
  • Pimpinella nodiflora (L.) Stokes

and 10 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. USDA PLANTS Database. common name, checklist symbol APNO. public domain. 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.