Acorus L.
  • L., Sp. Pl.: 324 (1753)
  • kalmusar

This taxon is accepted by WCS higher taxonomy

General Description

Laticifers absent, raphides absent.  Herbs, stem a  repent, much-branched, lacunose rhizome with aromatic oil cells. Leaves distichous, unifacial, ensiform, not differentiated into petiole and blade, intravaginal squamules present in leaf axils; primary veins parallel, higher order venation parallel. Inflorescence solitary, terminal, borne laterally on leaf-like scape, continuation shoot arising in axil of leaf preceding spathe. Spathe  longer than spadix, erect, persistent, appearing merely as a vertical extension of the leaf-like peduncle. Spadix  jutting out at an angle from peduncle, conoid and finger-like or slender and tail-like.   Flowers bisexual, perigoniate, densely arranged, bractless, 3-merous; tepals 6, in 2 whorls of 3, thin, fornicate. Stamens  6, in 2 whorls of 3, filaments linear, anthers introrse, thecae rounded-elliptic, subopposite, dehiscing by longitudinal slit, connective inconspicuous. Pollen monosulcate to subulcerate, ellipsoid, small (mean 18 µm; range 15-20 µm), exine shallowly and remotely or more densely foveolate, otherwise psilate, apertural exine subpsilate. Gynoecium obconic-oblong, equalling tepals, 2-3-locular, ovules several per locule, pendent, orthotropous, both integuments bearing trichomes, inner integument longer than outer and forming micropyle, placenta apical, stigma minute, sessile. Berry  oblong-obovoid with thin, leathery pericarp, enclosed by tepals, 1-5(-9)-seeded, whitish with brownish stigma remnant when fresh, soon drying to straw-brown. Seed  oblong to ellipsoid, testa light brown, foveolate (A. calamus) or smooth (A. gramineus), long integumentary trichomes present (A. gramineus) or absent, embryo axile, cylindric or conoid (A. gramineus), perisperm present, endosperm copious.


Temperate to tropical wetlands, up to 1100m alt. in central Europe and up to 2600m alt. in China; helophyte, marshes, streams, ponds, swampy sites, pastures, meadows.


Temperate to subtropical Asia and North America; introduced and naturalized in Europe.

Distribution Map

  • Native distribution
  • Introduced distribution
Found in
  • Asia-Temperate China China North-Central
  • China South-Central
  • China Southeast
  • Hainan
  • Inner Mongolia
  • Manchuria
  • Qinghai
  • Tibet
  • Xinjiang
  • Eastern Asia Japan
  • Korea
  • Taiwan
  • Middle Asia Kazakhstan
  • Kirgizistan
  • Uzbekistan
  • Mongolia Mongolia
  • Russian Far East Amur
  • Khabarovsk
  • Kuril Is.
  • Primorye
  • Sakhalin
  • Siberia Altay
  • Buryatiya
  • Chita
  • Irkutsk
  • Krasnoyarsk
  • Tuva
  • West Siberia
  • Yakutskiya
  • Asia-Tropical Indian Subcontinent Assam
  • Bangladesh
  • East Himalaya
  • India
  • Laccadive Is.
  • Maldives
  • Nepal
  • Pakistan
  • Sri Lanka
  • West Himalaya
  • Indo-China Cambodia
  • Laos
  • Myanmar
  • Thailand
  • Vietnam
  • Malesia Borneo
  • Jawa
  • Lesser Sunda Is.
  • Malaya
  • Philippines
  • Sulawesi
  • Northern America Eastern Canada New Brunswick
  • Newfoundland
  • Nova Scotia
  • Ontario
  • Prince Edward I.
  • Québec
  • North-Central U.S.A. Illinois
  • Iowa
  • Kansas
  • Minnesota
  • Nebraska
  • North Dakota
  • South Dakota
  • Wisconsin
  • Northeastern U.S.A. Connecticut
  • Indiana
  • Maine
  • Masachusettes
  • Michigan
  • New Hampshire
  • New Jersey
  • New York
  • Ohio
  • Pennsylvania
  • Rhode I.
  • Vermont
  • Northwestern U.S.A. Idaho
  • Montana
  • Washington
  • Southeastern U.S.A. District of Columbia
  • Virginia
  • Subarctic America Alaska
  • Northwest Territories
  • Western Canada Alberta
  • British Columbia
  • Manitoba
  • Saskatchewan
Introduced into
  • Africa Southern Africa Cape Provinces
  • Asia-Temperate Caucasus North Caucasus
  • Transcaucasus
  • Asia-Tropical Indo-China Andaman Is.
  • Papuasia New Guinea
  • Europe Eastern Europe Baltic States
  • Belarus
  • Central European Russia
  • East European Russia
  • Krym
  • North European Russia
  • Northwest European Russia
  • South European Russia
  • Ukraine
  • Middle Europe Austria
  • Belgium
  • Czechoslovakia
  • Germany
  • Hungary
  • Netherlands
  • Poland
  • Switzerland
  • Northern Europe Denmark
  • Finland
  • Føroyar
  • Great Britain
  • Iceland
  • Ireland
  • Norway
  • Svalbard
  • Sweden
  • Southeastern Europe Albania
  • Bulgaria
  • Greece
  • Italy
  • Kriti
  • Romania
  • Sicilia
  • Turkey-in-Europe
  • Yugoslavia
  • Southwestern Europe France
  • Northern America North-Central U.S.A. Missouri
  • Oklahoma
  • Northeastern U.S.A. West Virginia
  • Northwestern U.S.A. Colorado
  • Oregon
  • South-Central U.S.A. Texas
  • Southeastern U.S.A. Alabama
  • Arkansas
  • Delaware
  • Georgia
  • Kentucky
  • Louisiana
  • Maryland
  • Mississippi
  • North Carolina
  • South Carolina
  • Tennessee
  • Southwestern U.S.A. California

Common Names

kalmusrotslektaNorwegian Nynorsk
kalmusrotslektaNorwegian Bokmål


  • 1 Boyce, P.C., Sookchaloem, D., Hetterscheid, W.L.A., Gusman, G., Jacobsen, N., Idei, T. & Nguyen, V.D. (2012). Flora of Thailand 11(2): 101-325. The Forest Herbarium, National Park, Wildlife and Plant Conservation Department, Bangkok.
  • 2 Govaerts, R. & Frodin, D.G. (2002). World Checklist and Bibliography of Araceae (and Acoraceae): 1-560. The Board of Trustees of the Royal Botanic Gardens, Kew.
  • 3 Govaerts, R. (1995). World Checklist of Seed Plants 1(1, 2): 1-483, 1-529. MIM, Deurne.
  • 4 Linnaeus, C. Original publication of Acorus. Pl., (1753).
  • 5 Mayo, S.J., Bogner, J., Boyce, P.C. & Catherine, E. The genera of Araceae. 370 (Royal Botanic Gardens, Kew: London, 1997).

 Information From

OpenUp Common Names
Common Names from the OpenUp! Common Names Service
  • A All Rights Reserved
WCS higher taxonomy
  • B All Rights Reserved
World Checklist of Selected Plant Families
WCSP 2014. 'World Checklist of Selected Plant Families. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; Retrieved 2011 onwards
  • C See You may use data on these Terms and Conditions and on further condition that: The data is not used for commercial purposes; You may copy and retain data solely for scholarly, educational or research purposes; You may not publish our data, except for small extracts provided for illustrative purposes and duly acknowledged; You acknowledge the source of the data by the words "With the permission of the Trustees of the Royal Botanic Gardens, Kew" in a position which is reasonably prominent in view of your use of the data; Any other use of data or any other content from this website may only be made with our prior written agreement.