Originally published on Herbal Medicine from Your Garden
Sweet flag, Acorus calamus, is also known by many other names, including calamus, calamus root, flag root, muskrat root, myrtle flag, rat root, sweet calomel, sweet rush and sweet sedge. It is found growing all over the world, though it is believed to have originated in Asia. It is not related to the blue flag, bog myrtle, common myrtle, lemon myrtle or allspice (sometimes called myrtle pepper).
Sweet flag is a hardy perennial which reaches a height and spread of 1m (3 feet). It grows in wet soil or in water. Type of soil is not important, but the plant will not grow in full shade. It can be propagated from seed, which should be surface sown onto moist or wet soil as soon as the seeds are available and not allowed to dry out. Once plants are big enough to handle they can be moved to a sheltered area, but must be kept moist or wet at all times until they are transplanted to their final position, on the edge or in the margins of a pond, where the soil is always moist or even flooded.
The American poet Walt Whitman wrote 39 poems about the sweet flag, known as the Calamus poems, in his book Leaves of Grass, and it was also a favorite of the naturalist Henry David Thoreau.
Sweet flag is the favorite food of the American musk rat and perhaps because of this, as well as its use in medicine, native Americans planted it everywhere they went. It’s now found across North America in water close to former native American settlements, camping areas and trails.
Take care not to confuse this plant with the poisonous blue flag, left (sometimes called poison flag), a species of Iris which grows in the same habitat. If either plant is in flower, this is easy to achieve, but otherwise you can tell them apart by fragrance. Sweet flag has a pleasant, sweet fragrance, whereas blue flag does not. If there is any doubt, it is wise not to harvest the plant, as an error may prove fatal. However, if you are able to grow sweet flag, this difficulty can be avoided (so long as you don’t also grow its poisonous namesake).
Acorus calamus and derivatives, as well as products containing them, were banned by the US Food and Drug Administration in 1968 for use in food or food supplements offered for sale. The reason given relates to tests done on rats fed with large quantities of an extract (beta-asarone) of the tetraploid form of the plant (found in East Asia, India and Japan), which is not found in the diploid and triploid forms which grow in Europe and North America (even though beta-asarone is not found in European and North American plants). For this reason, the essential oil (which is a highly concentrated extract) is not recommended for medicinal use, because it may be dangerous. It’s possible that the real reason for this ban is the plant’s hallucinogenic properties. The 60s were a time when natural hallucinogens were popular for recreational purposes, much to the annoyance of Western governments.
The part used in herbal medicine is the rhizome (an underground stem, often mistakenly called a root), which should be harvested in late fall or early spring when plants are no more than 3 years old and used immediately or dried for later use. Other parts may be used in the kitchen – the leaves to flavor custard (by immersion in the milk while it is heating, removed before serving), young leaves can be cooked, and the peeled stems used uncooked in salad. Young flowers are sweet, and can also be eaten uncooked.
Don’t store dried roots for more than a few months, as they deteriorate quickly.
Sweet flag is an amazingly versatile addition to the herbal medicine cabinet. However, it is definitely not suitable for use during pregnancy, as it may cause miscarriage.
Historically, sweet flag has been used all over the world for many different purposes. It was listed in the US National Formulary for medicinal use on humans until 1950. In traditional Chinese medicine it is used to treat deafness, dizziness and epilepsy. In Ayurvedic medicine it is valued as a rejuvenator for the brain and nervous system, and as a remedy for digestive disorders. The Dakotas used it to treat diabetes.
If you’ve never used sweet flag before, start with a low dose. If this does not work, increase the dose but don’t overdo it. Taking too large a dose can cause nausea, vomiting and hallucinations. Do not use sweet flag for a long period. Alternate with other remedies for longstanding conditions.
The most common way of using sweet flag is by chewing it; a normal dose is about 5cm (2 inches). Normally, you chew it without swallowing until you feel you’ve had enough (this may sound a bit hit and miss, but isn’t unusual with folk remedies, which are generally milder than the chemicals used in conventional medicine). Try not to swallow the chewed root, as it may cause a stomach upset. Dispose of the chewed root in the trash.
You can also make a standard infusion using 1 tsp of dried rhizome to 120ml (half US cup, 4 fl oz) boiling water, leaving it to steep for 5 minutes before straining for use. A decoction can be made by adding 1 tbsp of dried rhizome to 240ml (1 US cup, 8 fl oz) cold water, bring to a boil and boil for a few minutes, then strain. The dosage for the standard infusion or decoction is up to 240ml/1 cup a day, split into 3 doses.
Another way to use it is as a herbal bath: add 450gm (1lb) of dried rhizome to 5 litres (5 US quarts, 1 UK gallon) of cold water, bring to a boil and turn off the heat, steep for 5 minutes, strain off the herb and throw away, then add the liquid to the bath water. Check that the bath water has not been made too hot by the addition of such a large quantity of very hot water before getting in!
There are so many uses, I’ve split them up as follows:
- soothes and relieves pain (mainly toothache, sore gums and sore throat).
- chew the rhizome to kill the taste for tobacco (may induce nausea)
- Arabic, Ancient Roman and traditional European herbals recommend it as an aphrodisiac which increases sexual desire. The traditional treatment for this purpose is a herbal bath.
- stimulates and restores the appetite, recommended in the treatment of anorexia nervosa.
- stimulant and mild tonic, especially useful when you don’t feel you have enough energy to finish a job which must be completed before you can rest.
- expels excessive gas (and reduces its production) and relaxes the bowel, useful for digestive problems such as flatulence (“gas” or “wind“), bloating and colic.
- promotes perspiration.
- promotes menstruation.
- promotes flow of mucus from respiratory passages and makes tickly coughs productive. Also relieves sinusitis by acting on the mucous membranes.
- reduces or eliminates fevers.
- lowers blood pressure.
- treats toothache and other tooth and gum problems, chewing the root alleviates toothache.
- remedy for digestive disorders; small doses reduce stomach acidity; larger doses increase stomach secretions. It also stimulates the salivary glands.
- has a calming effect and can be used to treat panic and anxiety attacks, or for shock. Chew a piece of the rhizome and breathe slowly and deeply while doing so.
- for brain and nervous system to manage neuralgia and epilepsy and treat memory loss.
- destroys intestinal parasites.
It is also used externally to treat skin eruptions, rheumatic pains and neuralgia.
As with all herbs grown for medicinal use, it’s important to grow sweet flag organically, and this is particularly the case for herbs which grow in water. If you have fish, then you will probably already be avoiding chemicals in the water, but in any case if you have trouble with algae, it’s important that you find an organic treatment, because chemicals will find their way into the plants and dilute or entirely eliminate the active constituents.To find out more about growing organic herbs visit the Gardenzone.