Calamus (acorus calamus)

Native to India, Europe, and North America, this irislike perennial grows worldwide, especially in wet places. During the Middle Ages, the aromatic yellow-green leaves of calamus were strewn on the floors of churches and houses to ward off fleas, lice, and other pests. In modern India, the powdered rhizome is used as an insecticide to protect stored crops, such as rice.

Although traditional medicine has ascribed many healing properties to this grassy-looking herb, the FDA has judged it unsafe and has banned its use in food and medicines. The essential oil of the root of most varieties contains compounds (asarone and beta-asarone) known to promote tumor formation, although the roots of certain North American and East Asian varieties contain much less of these compounds.

Acorus calamus

Plant profile

Common Names: Calamus, Cinnamon Sedge, Sweet Flag, Sweet Myrtle

Description: Erect, sword-shaped leaves up to 5 feet long; small yellow-green to brown flowers; thick, creeping rhizomes; aromatic

Hardiness: To Zone 4

Family: Acoraceae

Flowering: Midsummer

Parts Used: Rhizome

Range/Habitat: Native to Asia, Europe, and North America; wet soils and shallow water in ditches, marshes, river edges, and ponds

Medicinal use

In traditional medicine, the dried rhizome is chewed or taken as a tea or tincture to stimulate appetite and relieve indigestion, as well as many other conditions of the digestive, nervous, circulatory, respiratory, urinary, and reproductive systems. Calamus has anti-inflammatory and analgesic properties; in Ayurvedic medicine and other therapies, a paste of the rhizome is used externally to treat rheumatoid arthritis, osteoarthritis, and hemiplegia—a type of paralysis that affects one side of the body.

Known in Sanskrit as vacha (“vocabulary power” or “speech”), calamus is also thought to bring clarity to the mind and improve spoken language. In Ayurveda, the herb is used to treat stroke victims and epilepsy. Native American tribes chewed pieces of the root to instill energy and focus the mind.

Caution: Depending on its chemical composition and variety, this plant can be very harmful. In animal studies, malignant tumors occurred in rats exposed to high doses of calamus.

Other uses

Sweetly scented calamus has long been used in perfumery. The rhizome can also be added to potpourris and sachets.

How to grow it

Grow this aquatic plant in a sunny location in shallow water or rich, wet soil with a pH of 5.0 to 7.0. In a marsh or at a pond’s edge is ideal. In spring or fall, plant the rhizomes 4 to 6 inches deep and 1 foot apart. Harvest large, 2- to 3-year-old rhizomes in early spring or late fall. Propagate by dividing the rhizomes in spring or fall after several years of growth.