This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
Calamus. - Synonym. - Sweet Flag. The rhizome of Acorus Calamus Linne (nat. ord. Aroideae).
Europe and North America, on the banks of streams and ponds.
In sections of various lengths, unpeeled, about 2 cm. broad, subcylindrical, longitudinally wrinkled; on the upper surface marked with leaf-scars forming triangles, and on the lower surface with the circular scars of the rootlets in wavy lines; externally reddish-brown, somewhat annulate from remnants of leaf-sheaths; internally whitish, of a spongy texture, breaking with a short, corky fracture, showing numerous oil-cells and scattered wood-bundles, the latter crowded within the subcircular endoderm. It has an aromatic odor, and a strongly bitter taste. As found in the shops it is generally peeled.
Sweet flag is a simple bitter and feeble aromatic, and is used with advantage in pain or uneasiness in the stomach or bowels arising from flatulence, or as an adjuvant to purgative medicines.