Acorus

Acorus is a genus of flowering plants in the family Acoraceae, and it is the only genus in that family. The genus comprises several species commonly known as sweet flag and is native to wetlands across Europe, Asia, and North America. These plants are often found in marshy, riparian, and swampy habitats.

Acorus species are perennial, rhizomatous herbs. They have long, linear, ribbonlike leaves that arise from creeping rhizomes and are usually aromatic when crushed. The inflorescence is a short spike borne on a stalk, enclosed by a leaflike spathe; flowers are small and greenish and typically not showy.

The best-known species is Acorus calamus, often called sweet flag or calamus. Other recognized species include Acorus gramineus (Japanese sweet flag) and Acorus americanus (American sweet flag). Taxonomic status can vary by authority, with some treatments recognizing A. americanus as distinct from or as a variant of A. calamus. In some classifications, A. americanus is treated as a separate North American species, while others treat it as a regional form or synonym.

Habitat and cultivation: In the wild, Acorus grows in wetlands, marsh edges, and along stream banks. It is widely cultivated as an ornamental plant in ponds and water gardens and is valued for its low, clumping habit and architectural leaves. It propagates readily by rhizomes and can naturalize in suitable sites.

Uses and safety: Acorus has been used in traditional medicine and for its essential oils in perfumery. However, beta-asarone, a constituent found in A. calamus, has been linked to safety concerns, leading to regulatory restrictions on certain preparations in various countries. Care should be taken when using internal products containing this compound.