Calamus

Calamus is a medicinal herb, Acorus calamus, also known as sweet flag. Its dried rhizomes are used in the formulation of vermouths, liqueurs and bitters, contributing a bitter-aromatic note, and the plant also has traditional medicinal and veterinary uses. Because some varieties contain beta-asarone, a compound of toxicological concern, the use of calamus in foods and beverages is restricted or banned in several countries. Where permitted, only low-asarone varieties may be used, and levels are controlled. Traditional medicine has used it for digestive complaints, but modern food law treats it cautiously because of the beta-asarone content of many varieties.