sweet flag

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A hardy perennial herb (Acorus calamus) of the Northern Hemisphere, growing in marshy places and having grasslike leaves, minute greenish flowers borne on a thick spadix, and aromatic rhizomes. Also called calamus.

Century Dictionary and Cyclopedia

1. n. An araceous plant, Acorus Calamus, with sword-shaped leaves and two-edged leaf-like scapes, from one edge of which emerges a cylindrical spadix. It has a pungent and aromatic property, especially its thick creeping rootstock, which forms the officinal calamus aromaticus. This is now sparingly used as a stomachic, also in confectionery and in kinds of distilling and brewing. Also calamus, sweet-rush, sweet sedge.

Wiktionary

1. n. a perennial wetland plant, Acorus calamus, with an aromatic medicinal root, formerly used to strew floors, also known as calamus

GNU Webster's 1913

1. n. See Calamus, n., 2.
2. adj. (Bot.) an endogenous plant (Acorus Calamus) having long flaglike leaves and a rootstock of a pungent aromatic taste. It is found in wet places in Europe and America. See Calamus, 2.

WordNet 3.0

1. n. perennial marsh plant having swordlike leaves and aromatic roots