Acorus calamusL.

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WFO wfo-0000350733 Accepted WFO 2026-06 8 photographs CC0 / CC BY / CC BY-SA

Plate 1 figs. a–h · 8 separate observations

Acorus calamus, photographed by Alexander Dubynin
fig. a Alexander Dubynin, CC BY 4.0 / 2021-08-11 / obs. 155071139
Acorus calamus, photographed by Grzegorz Grzejszczak
fig. b Grzegorz Grzejszczak, CC BY-SA 4.0 / obs. 176676721
Acorus calamus, photographed by Lynn Harper
fig. c Lynn Harper, CC0 1.0 / obs. 139364114
Acorus calamus, photographed by Pavel Šmejkal
fig. d Pavel Šmejkal, CC BY 4.0 / obs. 137438112
Acorus calamus, photographed by Lynn Harper
fig. e Lynn Harper, CC0 1.0 / obs. 134827049
Acorus calamus, photographed by Jason Grant
fig. f Jason Grant, CC BY 4.0 / obs. 131525554
Acorus calamus, photographed by Grzegorz Grzejszczak
fig. g Grzegorz Grzejszczak, CC BY-SA 4.0 / obs. 119309124
Acorus calamus, photographed by Svetlana Polevova
fig. h Svetlana Polevova, CC0 1.0 / obs. 90114962

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 56 botanical countries

Regions where Acorus calamus is native: Altay, Amur, Buryatiya, China North-Central, China Southeast, Inner Mongolia, Irkutsk, Japan, Kamchatka, Kazakhstan, Khabarovsk, Korea, Krasnoyarsk, Kuril Is., Manchuria, Mongolia, Primorye, Qinghai, Sakhalin, Tibet, Tuva, West Siberia, Xinjiang, Yakutiya, Alaska, Alberta, British Columbia, Connecticut, Idaho, Iowa, Kansas, Maine, Manitoba, Massachusetts, Michigan, Minnesota, Montana, Nebraska, New Brunswick, New Hampshire, New York, Newfoundland, Northwest Territories, Nova Scotia, Nunavut, Ohio, Ontario, Pennsylvania, Prince Edward I., Québec, Saskatchewan, South Dakota, Vermont, Washington, Wisconsin, Yukon AltayAmurBuryatiyaChina North-CentralChina SoutheastInner MongoliaIrkutskJapanKamchatkaKazakhstanKhabarovskKrasnoyarskManchuriaMongoliaPrimoryeQinghaiSakhalinTibetTuvaWest SiberiaXinjiangYakutiyaAlaskaAlbertaBritish ColumbiaConnecticutIdahoIowaKansasMaineManitobaMassachusettsMichiganMinnesotaMontanaNebraskaNew BrunswickNew HampshireNew YorkNewfoundlandNorthwest TerritoriesNova ScotiaNunavutOhioOntarioPennsylvaniaPrince Edward I.QuébecSaskatchewanSouth DakotaVermontWashingtonWisconsinYukon Korea
Native distribution of Acorus calamus, 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
Alaska ASK NORTHERN AMERICA
Alberta ABT
British Columbia BRC
Connecticut CNT
Idaho IDA
Iowa IOW
Kansas KAN
Maine MAI
Manitoba MAN
Massachusetts MAS
Michigan MIC
Minnesota MIN
Montana MNT
Nebraska NEB
New Brunswick NBR
New Hampshire NWH
New York NWY
Newfoundland NFL
Northwest Territories NWT
Nova Scotia NSC
Nunavut NUN
Ohio OHI
Ontario ONT
Pennsylvania PEN
Prince Edward I. PEI
Québec QUE
Saskatchewan SAS
South Dakota SDA
Vermont VER
Washington WAS
Wisconsin WIS
Yukon YUK
Altay ALT ASIA-TEMPERATE
Amur AMU
Buryatiya BRY
China North-Central CHN
China Southeast CHS
Inner Mongolia CHI
Irkutsk IRK
Japan JAP
Kamchatka KAM
Kazakhstan KAZ
Khabarovsk KHA
Korea KOR
Krasnoyarsk KRA
Kuril Is. KUR
Manchuria CHM
Mongolia MON
Primorye PRM
Qinghai CHQ
Sakhalin SAK
Tibet CHT
Tuva TVA
West Siberia WSB
Xinjiang CHX
Yakutiya YAK

Not drawn on the map: Kuril Is.. 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 66 in flower of 171 examined

Peak flowering in Jun. Each bar is the share of Acorus calamus 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. 66 of 171 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 7 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.

Where it actually grows measured, from 1,704 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -19.0 °C -6.5 °C 1.6 °C
Warmest month, mean daily high 20.3 °C 23.3 °C 30.0 °C
Annual rainfall 452 mm 684 mm 1,255 mm
Rainfall in the driest quarter 54 mm 116 mm 259 mm

It is found where winters are severely cold. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 1,704 research-grade observations of Acorus calamus 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 39 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.

  • Acorus americanus (Raf.) Raf.
  • Acorus angustatus Raf.
  • Acorus angustifolius Schott
  • Acorus aromaticus Gilib.
  • Acorus asiaticus Nakai
  • Acorus belangeri Schott
  • Acorus calamus f. submersa Glück
  • Acorus calamus subsp. vulgaris (L.) Ehrh.
  • Acorus calamus var. angustifolius (Schott) Engl.
  • Acorus calamus var. belangeri (Schott) Engl.
  • Acorus calamus var. europeus Raf.
  • Acorus calamus var. spurius (Schott) Engl.
  • Acorus calamus var. verus L.
  • Acorus calamus var. vulgaris L.
  • Acorus calamus-aromaticus Clairv.
  • Acorus casia Bertol.
  • Acorus cochinchinensis (Lour.) Schott
  • Acorus commersonii Schott
  • Acorus commutatus Schott
  • Acorus elatus Salisb.
  • Acorus europaeus Dumort.
  • Acorus flexuosus Raf.
  • Acorus floridanus Raf.
  • Acorus gramineus var. crassispadix Lingelsh.

and 15 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.