ACORUS CALAMUS, sweet-sedge or sweet-flag, a plant of the natural order Araceae, which shares with the Cuckoo Pint (Arum) the representation in Britain of that order of Monocotyledons. The name is derived from acorus, Gr. ἄκορος, the classical name for the plant. It was the Calamus aromaticus of the medieval druggists and perhaps of the ancients, though the latter has been referred by some to the Citron grass, Andropogon Nardus. The spice “Calamus” or “Sweet-cane” of the Scriptures, one of the ingredients of the holy anointing oil of the Jews, was perhaps one of the fragrant species of Andropogon. The plant is a herbaceous perennial with a long, branched root-stock creeping through the mud, about 34 inch thick, with short joints and large brownish leaf-scars. At the ends of the branches are tufts of flat, sword-like, sweet-scented leaves 3 or 4 ft. long and about an inch wide, closely arranged in two rows as in the true Flag (Iris); the tall, flowering stems (scapes), which very much resemble the leaves, bear an apparently lateral, blunt, tapering spike of densely packed, very small flowers. A long leaf (spathe) borne immediately below the spike forms an apparent continuation of the scape, though really a lateral outgrowth from it, the spike of flowers being terminal. The plant has a wide distribution, growing in wet situations in the Himalayas, North America, Siberia and various parts of Europe, including England, and has been naturalized in Scotland and Ireland. Though regarded as a native in most counties of England at the present day, where it is now found thoroughly wild on sides of ditches, ponds and rivers, and very abundantly in some districts, it is probably not indigenous. It seems to have been spread in western and central Europe from about the end of the 16th century by means of botanic gardens. The botanist Clusius (Charles de l’Escluse or Lécluse, 1526–1609) first cultivated it at Vienna from a root received from Asia Minor in 1574, and distributed it to other botanists in central and western Europe, and it was probably introduced into England about 1596 by the herbalist Gerard. It is very readily propagated by means of its branching root-stock. It has an agreeable odour, and has been used medicinally. The starchy matter contained in its rhizome is associated with a fragrant oil, and it is used as hair-powder. Sir J. E. Smith (Eng. Flora, ii. 158, 2nd ed., 1828) mentions it as a popular remedy in Norfolk for ague. In India it is used as an insectifuge, and is administered in infantile diarrhoea. It is an ingredient in pot-pourri, is employed for flavouring beer and is chewed to clear the voice; and its volatile oil is employed by makers of snuff and aromatic vinegar. The rhizome of Acorus Calamus is sometimes adulterated with that of Iris Pseudacorus, which, however, is distinguishable by its lack of odour, astringent taste and dark colour.