This is the root (rhizome) of Acorus Calamus or sweet flag, an indigenous plant growing also in Europe and Western Asia, and, in this country, abounding in low, meadowy grounds, too wet for the culture of the useful grasses. The plant may be distinguished, by those not acquainted with its botanical character, from the young cat-tails, and coarse grasses with which it is frequently associated, by the aromatic odour of the leaves when bruised, and their aromatic taste. The root is horizontal, jointed, somewhat flattened above and below, often several feet long, from half an inch to an inch thick, with numerous fibres or radicles proceeding from its under surface, which are cut off when it is dried, leaving little, round, permanent spots. When dried, it shrinks much. As kept in the shops, it is in pieces of various lengths, wrinkled, yellowish-brown externally, and whitish or yellowish-white internally. In some pieces the exterior cortical part has been removed, leaving the inner portion, the surface of which acquires a grayish-white colour. The odour is strong and fragrant; the taste warm, bitterish, pungent, and aromatic. It yields its virtues to boiling water. These may be considered as residing exclusively in a volatile oil, which is occasionally separated by distillation, is yellow, and has an odour and taste analogous to those of the root. There is said also to be an acrid extractive matter; but too little is known of it to justify the ascribing to it of any of the virtues of the medicine. Starch is another ingredient.

Calamus has been known from ancient times. It has medical virtues closely analogous to those of ginger, for which it might be substituted in most cases, though it is generally much less acceptable to the palate. There is one use of it which I would recommend from experience. Having some tenacity, though sufficiently brittle to be easily broken by the teeth, it may be carried in the pocket, and a little of it chewed as wanted. In this way it will often afford great relief to the gastric uneasiness, spasmodic pains, and flatulence so frequently attendant on dyspesia, nervous gout, and hysterical affections. The dose of it is from twenty grains to a drachm. An infusion, made with half an ounce or an ounce to a pint of boiling water, may be taken in the dose of two fluidounces or more. In the form of powder, calamus is said to have a strong preservative influence against the attacks of insects, if sprinkled over the object to be preserved. {Med. and S. Reporter, Sept. 24, 1864, p. 107)