A.calamus is a semi-aquatic, perennial, aromatic herb with creeping rhizomes. The rhizome is horizontal, jointed, somewhat vertically compressed and spongy within. It is pale to dark brown in colour; the leaves are grass-like or sword shaped, long and slesnder; flowers are small, yellow-green and in a spadix.

The important constituents are asarone and its ß-isomer. The dried rhizomes constitute the drug Calamus of commerce. The rhizomes, roots and leaves yield a light brown to brownish yellow volatile oil known as Calamus oil.