Botanical name: 

The rhizome of Acorus Calamus, Linné (Nat. Ord. Acoraceae). Common in wet and muddy grounds everywhere in the Northern Hemisphere. Dose, 5 to 40 grains.
Common Name: Sweet-flag.

Principal Constituents.—Resin, aromatic essential oil, and a bitter glucoside, acorin (C36H60O6).
Preparations.—I. Specific Medicine Calamus. Dose, 5 to 30 drops.
2. Syrupus Calami, Syrup of Calamus. Dose, 30 to 60 drops.

Action and Therapy.—Carminative, sialagogue, excitant, and slightly tonic. Useful as 'breath perfume," and in flatulent colic, atonic dyspepsia, feebleness of the digestive organs; and in the form of syrup as an agreeable vehicle for less pleasant medicines. The fresh root shaved thin, transversely, may be candied by boiling in syrup, draining, and allowing it to dry. In this form it is a delicious confection. Calamus may also be given in the form of a syrup or by adding the specific medicine to the required amount of simple syrup.

The Eclectic Materia Medica, Pharmacology and Therapeutics, 1922, was written by Harvey Wickes Felter, M.D.