Sweet Flag

Acorus calamus var. americanus, syn. Calamus aromaticus

Also known as Muskrat Root, this is a tall, moisture-loving perennial monocot growing to 2 metres tall from a rhizome. The sword shaped leaves are flat and narrow, but robust, and resemble those of the Iris family – the name “sweet flag” refers to its sweet scent and its similarity to Iris species, which have been referred to as ‘flags’ in English since the late fourteenth century.  The flower stems rise from the axils of the outer leaves, followed by a semi-erect spadix emerging from one side of the flower stem. The spadix is greenish-yellow, about 5 -10 cm  long, and sweetly smelling, and is said also to be sweet in taste.  However, only plants that grow in water bear these flowers.

Sweet Flag has a wide native range across the Northern hemisphere and has a long tradition of medicinal by native peoples in these areas. The root is anodyne, aphrodisiac, aromatic, carminative, diaphoretic, emmenagogue, expectorant, febrifuge, hallucinogenic, hypotensive, sedative, stimulant, stomachic, mildly tonic and vermifuge. Native Americans used it as a bitter and aromatic digestive, against tobacco or drug addiction, and to sharpen the mind. In Asia and Europe it has been used to treat gastrointestinal diseases and treating pain. Some studies have shown alcohol extracts of rhizome to have antifungal and antibacterial effects, to be highly effective against parasitic worms in humans, and to have potent antiviral activity against Herpes simplex virus.  Sweet Flag is prescribed in both Ayurvedic and Traditional Chinese medicine to treat memory loss and mental disorders, to improve learning performance and to inhibit aging effects.

The young stalks can be harvested when under 30 cm tall and the inner stems can be eaten raw. The roots can be washed, peeled, cut into small pieces, boiled, and simmered in syrup to make candy.  In Europe, the essence from the rhizome is used as a flavor for foods, alcoholic beverages such as beer, gin and vermouth, as well as cordials and bitters. Sometimes the roots has been used as a substitute for nutmeg, ginger or cinnamon.

CAUTION: Although used in traditional medicine across the world for centuries, there is no ‘clinical’ evidence for the safety of Sweet Flag. The essential oil in the roots may contain carcinogenic substances, may be toxic if ingested, and has been banned from commercial use in the United States. One of the difficulties however is that the plant exhibits polyploidy (where the cells of an organism have more than one pair of (homologous) chromosomes),  and the composition of the essential oil obtained from the plant rhizome depends on the genetic make up of each type. Beta asarone is the constituent which can cause positive effects such as tranquillising and antibiotic activity, but is also potentially toxic and carcinogenic. It seems that these compounds are found in the triploid form of the species (found in Asia) whilst the diploid form (found in North America and Siberia) is low in, or free from, the compounds.  Only roots free from or with a low content of beta asarone should be used in human herb therapy. The genotype which we have sourced is a low beta asarone strain native to the wetland areas of the northern prairie states of the USA.

Even if you don’t use this plant for its edible or medicinal properties, it is still well worth having for its multitude of other uses. Native Americans used it for basketry, and its aroma makes calamus essential oil highly valued in the perfume industry. Due to its scent it has also been used as a strewing herb and pieces of stem and rhizome put into drawers of clothing or dried and powdered and used in sachets or pot pourris.  The powdered rhizome is used as an insecticide for the destruction of fleas, lice, mites etc and is said to be effective in killing insect pests in stored rice (and considered to be better than chemicals for this purpose as it shows no residual effect.) Sweet Flag can be also be used in greywater treatment areas to filter and cleanse the water that runs through it. Apparently the Mongols always planted it near waterways to purify the water for their horses! Finally, the dried seed heads are interesting in flower arrangements.

Plants prefers full sun to part shade,  in or near water. It can withstand a variety of water levels, from very wet conditions to occasional shallow flooding. Frost hardy to about -25°c.

Certified organic plant in 11cm pot.