A species of Acorus (Acorus calamus), commonly called calamus, or sweet flag. The root has a pungent, aromatic taste, and is used in medicine as a stomachic; the leaves have an aromatic odor, and were formerly used instead of rushes to strew on floors.

Acorus calamus, a perennial aquatic herb with triangular stems and long creeping roots. It is also called Sweet Rush, Sweet Sedge, Sweet Flag and Muskrat Root.

the aromatic root of the sweet flag used medicinally

perennial marsh plant having swordlike leaves and aromatic roots

Native Americans chewed the root while running long distances to increase endurance and stamina. In China, calamus root is considered to have antiarrythmic, hypotensive, vasodilatory, antitussive, antibacterial and expectorant properties. It has been used to combat a lack of mental focus, stomach problems, acidity and as an aid to quite tobacco. Externally it is added to the bath to quiet the nerves and induce a state of tranquility. Tincture of calamus is useful as a parasitic when directly and frequently applied to lice and scabies infestations. Caution: avoid during pregnancy.