widespread in tropical and subtropical regions of the world
Acorus calamus L. (and varieties)
A. gramineus Sol.
introduced into many parts of the world
Perennial. Erect plant with creeping rhizome. Leaves in two sheathed rows, opposite distichous, equitant, linear, aromatic, with prominent midrib. Inflorescence a spadix, yellow-green, borne on stem that is fused with a leaf, arising approximately midway along leaf length. Spadix elongate, with numerous tiny bisexual flowers, spathe absent.
marshes, swamps, and open ponds
Acorus is often regarded as a close relative of the Arum family (Araceae) and is sometimes included in that family. This plant has been found to have various medicinal, insecticidal, and pharmacological qualities. Acorus spp. are used primarily as pond plants.
The taxonomy of the genus is complicated and currently accepted as two species, of which A. calamus has three varieties:
1. Acorus calamus L. – "Common sweet flag"; sterile triploid (native to Europe and Southern Asia).
-Acorus calamus var. americanus Raf.
-Acorus calamus var. angustatus Besser
-Acorus calamus var. calamus
2. Acorus gramineus Sol. ex Aiton – “Japanese sweet flag”; fertile diploid (China and Southeast Asia).