Some older studies indicated that it was placed in a lineage (the order Alismatales), that also includes aroids (Araceae), Tofieldiaceae, and several families of aquatic monocots (e.g., Alismataceae, Posidoniaceae).

This placement currently lacks support from traditional plant morphology studies, and some taxonomists still place it as a subfamily of Araceae, in the order Alismatales.

The APG III system recognizes order Acorales, distinct from the Alismatales, and as the sister group to all other monocots.

[citation needed] These plants are found in wetlands, particularly marshes, where they spread by means of thick rhizomes.

[15] A comparative study of its life history traits classified it as a "tussock interstitial", that is, a species that has a dense growth form and tends to occupy gaps in marsh vegetation, not unlike Iris versicolor.

Four varieties of A. calamus strains exist in nature: diploid, triploid, tetraploid and hexaploid.

Diploids are known to grow naturally in Eastern Asia (Mongolia and C Siberia) and North America.

[20][21][22] Research has consistently demonstrated that "β-asarone was not detectable in the North American spontaneous diploid Acorus [calamus var.

[citation needed] Fine-cut leaves used to be strewn across the floor in the Middle Ages, both for the scent, and for presumed efficacy against pests.