Botanical name: 

Calamus. U. S. VIII. Sweet Flag. Radix Calami Aromatica. Radix Acori. Sweet Sedge (Cane, Rush, Root or Myrtle). Myrtle-flag (Grass or Sedge). Acore Vrai, Fr. Cod. Acore Odorant, Fr. Rhizoma Calami, P. G. Kalmus, Kalmus-wurzel, G. Calamo aromatico, It. Sp.—"The unpeeled, dried rhizome of Acorus Calamus Linne (Fam. Araceae)." U. S. VIII. The sweet flag, or Calamus, has a perennial, horizontal, jointed, somewhat compressed rhizome, from half an inch to an inch thick, sometimes several feet in length, sending off numerous round and yellowish or whitish roots from its lower surface, and groups of brown fibers resembling coarse hair from its joints, internally white and spongy, externally whitish with a tinge of green, variegated with triangular leaf scars of light brown and rose color. The leaves are all radical, sheathing at the base, very long and sword-shaped. The scape or flower stem resembles the leaves, but is longer, and from one side, near the middle of its length, sends out a cylindrical spadix, tapering at each end, about two inches in length, and crowded with greenish-yellow flowers. The fruit is an oblong capsule, divided into three locules, and containing numerous oval seeds.

This plant grows abundantly in the wet places throughout the United States, Europe, Western and Southern Asia. The leaves as well as the rhizome have an aromatic odor; but the rhizome only is employed. It should be collected late in the autumn, or in the spring. After removal from the ground, the rhizomes are washed, freed from their roots, and dried with a moderate heat. Most of the commercial article has the outer portions of the cortex removed. By drying they lose nearly one-half their diameter, but are improved in odor and taste.

Calamus was officially described as follows: "Rhizome 1 to 2 cm. thick, usually in longitudinally split pieces of various lengths; when entire, cylindraceous and somewhat vertically flattened, externally reddish-brown, somewhat annulate from remnants of leaf-sheaths; upper surface with triangular leaf-scars, the lower surface with circular pitted scars of roots; fracture short, showing numerous oil cells and scattered fibro-vascular bundles, the latter crowded within the endodermis; odor aromatic; taste pungent and bitter." U. S. VIII.

The odor of Calamus is strong and fragrant; its taste warm, bitterish, pungent, and aromatic. Its active principles are taken up by boiling water. From 100 parts of the fresh root of the European plant, Trommsdorf obtained 0.1 of volatile oil. The volatile oil is contained in all portions of the plant, the leaves yielding to distillation, according to the analysis of Schimmel & Co., 0.2 per cent., the fresh root 1.5 to 3.5 per cent., the dried German root 0.8, and the Japan root as much as 5 per cent.

The oil is at first yellow, but ultimately becomes red, and has the odor and taste of Calamus. Kurbatow (Ann. Ch. Ph., vol. 173, p. 4) examined oil of Calamus, and found that the portion boiling below 170° C. (338° F.) yielded, after treatment with sodium, a terpene, C10H16, having a sp. gr. .8793 at 0° C. (32° F.), and having a boiling point of 158° C. (316.4° F.). The extractive matter has an acrid and sweetish taste. H. Thomas (A. Pharm., 1886, p. 465; P. J., 1886, p. 1085) obtained from Calamus rhizomes a bitter glucoside, acorin, in the form of a clear, thick, yellow liquid, having a neutral reaction and having the formula C36H60O6, splitting into oil of Calamus and sugar. By oxidation acoretin, a neutral resin, is formed, and from the extract remaining after the acorin is removed Thomas obtained an alkaloid which he named calamine. Calamus is sometimes attacked by worms, and deteriorates on keeping.

Uses.—Calamus is a feeble aromatic and as such is used, especially in domestic practice, in India and to some extent in other portions of the world. The volatile oil is largely used in perfumery, and the powdered root itself is esteemed in Ceylon and India as a vermifuge and an insecticide. Dose, in substance, fifteen to thirty grains (0.9-1.9 Gm.); of infusion (an ounce to one pint of boiling water), one to two wineglassfuls (60-120 mils).

The fluidextract, which was formerly official, Fluidextractum Calami U. S. VIII, was made as follows: "Calamus, in No. 40 powder, one thousand grammes [or 35 ounces av., 120 grains]; Alcohol, Water, each a sufficient quantity, to make one thousand mils [or 33 fluidounces, 6½ fluidrachms]. Mix seven hundred and fifty mils [or 25 fluidounces, 173 minims] of alcohol with two hundred and fifty mils [or 8 fluidounces, 218 minims] of water, and, having moistened the powder with three hundred and fifty mils .[or 11 fluid-ounces, 401 minims] of the mixture, pack it firmly in a cylindrical percolator; then add enough menstruum to saturate the powder and leave a stratum above it. When the liquid begins to drop from the percolator, close to the lower orifice, and, having closely covered the percolator, macerate for forty-eight hours. Then allow the percolation to proceed, gradually adding menstruum, using the same proportions of Alcohol and Water as before, until the. Calamus is exhausted. Reserve the first nine hundred mils [or 30 fluidounces, 208 minims] of the percolate, and evaporate the remainder, at a temperature not exceeding 50° C. (122° F.), to a soft extract; dissolve this in the reserved portion, and add enough menstruum to make the fluidextract measure one thousand mils [or 33 fluidounces, 6 ½ fluidrachms]." U. S. VIII. Dose, from fifteen to thirty minims (0.9-1.9 mils).

The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.