ACORUS CALAMUS, sweet-sedge or sweet-flag, a plant of the family Araceae, which shares with the Cuckoo Pint (Arum) the representation in Britain of that family of Monocotyledons. The name is derived from acorns, Gr. ilKopos, the classical name for the plant. It was the Calamus arornaticus of the mediaeval 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 a 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 4f t. 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.