Acorus or Sweet Flag, also known as calamus and various rushes and sedges, (Acorus calamus) is a plant from the Acoraceae family, in the genus Acorus. The morphological distinction between the Acorus species is made by the number of prominent leaf veins. Acorus calamus has a single prominent midvein and then on both sides slightly raised secondary veins (with a diameter less than half the midvein) and many fine tertiary veins. This makes it clearly distinct from Acorus americanus. Sweet flag has a very long history of medicinal use in many herbal traditions. It is widely employed in modern herbal medicine as an aromatic stimulant and mild tonic. In Ayurveda it is highly valued as a rejuvenator for the brain and nervous system and as a remedy for digestive disorders. However, some care should be taken in its use since some forms of the plant might be carcinogenic . The root is anodyne, aphrodisiac, aromatic, carminative, diaphoretic, emmenagogue, expectorant, febrifuge, hallucinogenic, hypotensive, sedative, stimulant, stomachic, mildly tonic and vermifuge. It is used internally in the treatment of digestive complaints, bronchitis, sinusitis etc. It is said to have wonderfully tonic powers of stimulating and normalizing the appetite. In small doses it reduces stomach acidity whilst larger doses increase stomach secretions and it is, therefore, recommended in the treatment of anorexia nervosa. However if the dose is too large it will cause nausea and vomiting. Sweet flag is also used externally to treat skin eruptions, rheumatic pains and neuralgia. An infusion of the root can bring about an abortion whilst chewing the root alleviates toothache. It is a folk remedy for arthritis, cancer, convulsions, diarrhoea, dyspepsia, epilepsy etc. Chewing the root is said to kill the taste for tobacco. Roots 2 - 3 years old are used since older roots tend to become tough and hollow. They are harvested in late autumn or early spring and are dried for later use. The dry root loses 70% of its weight, but has an improved smell and taste. It does, however, deteriorate if stored for too long. Caution is advised on the use of this root, especially in the form of the distilled essential oil, since large doses can cause mild hallucinations. A homeopathic remedy is made from the roots It is used in the treatment of flatulence, dyspepsia, anorexia and disorders of the gall bladder.