Acorus calamus L.
  • Sp. Pl.
  • Sweet-flag, calamus

This taxon is accepted by Acoraceae
Notes: More details could be found in The Plant List v.1.1. Originally in The Plant List v.1.0

General Description

Rhizome stout, 4-10(-20) × (0.8-)1-1.5(-3) cm, aromatic; roots at lower side of rhizome. Leaves several, mid-green, often reddish at base, ensiform, (60-)70-100(-150) × (0.7-)1-2(-2.5) cm (mostly 1-1.5 cm wide), apex acuminate; midrib conspicuous on both sides. Peduncle compressed triangular, (15-)40-50 cm. Spathe mid-green, leaflike, 30-50 cm, acute. Spadix straight or slightly curved, erect, oblique, narrowly conic to subcylindric (tapering toward apex), 4.5-6.5(-8) × 0.6-1.2(-1.5) cm, densely flowered. Flowers yellowish green, 1.8-2 mm in diam. seen from above; tepals oblong, 2.5-3 × 1-1.2(-1.4) mm, keeled, membranous, apex triangular hooded; filaments oblong, flat, 2-2.5 × 0.3-0.5 mm, anthers cream-colored, 0.4-0.5 mm in diam.; pollen grains ca. 20 µm, exine shallowly and remotely foveolate; gynoecium obconic-cylindric, 2.5-3.5(-4) × (0.8-)1-2.3 mm, with conic, spongy apex and stigma very small. Infructescence 1.5-2 cm in diam., straw-brown at maturity, berries densely arranged. Berry oblong-obovoid, 1- to few seeded, (3.5-)4-4.5 × 2-3(-3.5) mm. Seed oblong-ellipsoid to ovoid, 2.5-3(-4) × 1-1.2(-1.8) mm, without bristles; testa light brown, subsmooth and slightly foveolate. Fl. (Feb-)Apr-Sep. 2n = 24, 36, 48.

  • Provided by: [B].Flora Of CHina @
    • Source: [
    • 1
    • ]. 

    Leaves basally white with pink or red, otherwise bright green; single midvein (secondary midrib) prominently raised above leaf surface, usually somewhat off-center, other veins barely or not raised; cross section rhomboid. Vegetative leaves to 1.75 m; sheathing base (proximal part of leaf) 22.1--66.5(--73.3) cm; distal part of leaf 31.9--95.8(--117.6) ´ 0.5--2 cm, 1.4--1.8 times longer than proximal part of leaf, margins sometimes undulate or crisped. Sympodial leaf (29.9--)34.7--159.1(--183.9) cm, usually shorter than to nearly equal to vegetative leaves; sheathing base 16.1--76.4(--100.1) cm; distal part of leaf 13.5--86.2(--101.2) ´ 0.4--1.9 cm. Spadix (3.8--)4.9--8.9 cm ´ 5.3--10.8 mm at anthesis, post-anthesis spadix 5.5--8.7 cm ´ 6--12.6 mm. Flowers 3--4 mm; pollen grains not staining in aniline blue. Fruits not produced in North America. 2n = 36.

  • Provided by: [C].Flora of North America @
    • Source: [
    • 2
    • ]. 

    "Sweetly aromatic; lvs crowded at the base, erect, to 2 m, 8–25 mm wide; scape resembling the lvs, prolonged into an erect green spathe 2–6 dm; spadix 5–10 cm, 1 cm thick at anthesis, 2 cm at maturity, covered with yellowish-brown fls; fr 4–5 × 2 mm; 2n=18, 24, 36, 48. Swamps and shallow water; irregularly circumboreal, in Amer. from N.S. and Que. to Minn., Alta., and e. Wash., s. to Fla., Tex., and Colo. Spring and early summer. (A. americanus)"

  • Provided by: [E].New York Botanical Garden
    • Source: [
    • 3
    • ]. 


    Perennial herb. Strongly pungent aromatic oils present in all parts of plant. Leaves sword-shaped, 0.8-2.0 m long. Spathe leaf-shaped and green like spadix. Spadix appears lateral, green.

  • Provided by: [D].e-Flora of South Africa
    • Habitat

      Shallow, slow-flowing or stagnant water adjoining streambank edges, swamp areas.

    • Provided by: [D].e-Flora of South Africa
      • Distribution

        Native to Europe and Asia.

      • Provided by: [D].e-Flora of South Africa
        • Literature


          Motley, T. J. 1994. The ethnobotany of sweet flag, Acorus calamus (Araceae). Econ. Bot. 48: 397--412.

        • Provided by: [C].Flora of North America @
          • Source: [
          • 2
          • ]. 

          Local Names

          Sweet-flag, calamus


           Information From

          World Flora Online Data. 2017.
          • A CC0 1.0 Universal (CC0 1.0).
          Flora Of CHina @

          'Flora of China @ eFloras (2008). Published on the Internet [accessed August 2016]' Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
          • B Missouri Botanical Garden
          Flora of North America @

          'Flora of North America @ eFloras (2008). Published on the Internet [accessed August 2016]' Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
          • C Flora of North America Association
          e-Flora of South Africa

          e-Flora of South Africa. v1.21. 2018. South African National Biodiversity Institute.
          • D South African National Biodiversity Institute
          New York Botanical Garden
          Descriptions of plants should be attributed to the full citation for each individual article, chapter or book that is the source for each record, which should include the authors of original publication.
          • E Content licensed under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
          World Flora Online consortium

          World Flora Online Data. 2018.
          • F CC0 1.0 Universal (CC0 1.0).
          International Union for Conservation of Nature

          IUCN 2016. IUCN Red List of Threatened Species. Version 2016-2
          • G See IUCN Terms and conditions of use