Practical
Plants

Acorus calamus

Sweet Flag

a perennial member of the Acorus genus in the family Araceae.

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Taxonomy and growth

Family
Araceae
Genus
Acorus
Life cycle
perennial
Height
1 m
Spread
1 m
Flower type
hermaphrodite

Uses

Toxicity

Toxicity warning. The historical record reports a hazard for this plant. Do not use it to decide which parts are safe to eat or use medicinally.

This section contains historical Plants For A Future notes marked noncommercial.

The fresh root can be poisonous[36]. When using the plant medicinally, the isolated essential oil should not be used[9]. The essential oil in the roots of some populations of this plant contains the compound asarone. This has tranquillising and antibiotic activity, but is also potentially toxic and carcinogenic[23][24]. It seems that these compounds are found in the triploid form of the species (found in Asia) whilst the diploid form (found in N. America and Siberia) is free of the compounds[23][24]. However, the root (but not the isolated essential oil) has been used in India for thousands of years without reports of cancer which suggests that using the whole herb is completely safe, though more research is needed[28].

Edible uses

This section contains historical Plants For A Future notes marked noncommercial.

The rhizome is candied and made into a sweetmeat[17][31][5][32][35][4][14]. It can be peeled and washed to remove the bitterness and then eaten raw like a fruit[3][13]. It makes a palatable vegetable when roasted[16] and can also be used as a flavouring[34]. Rich in starch, the root contains about 1% of an essential oil that is used as a food flavouring[1][5][33]. The root also contains a bitter glycoside[13]. Some caution is advised, see the notes above on toxicity. The dried and powdered rhizome has a spicy flavour and is used as a substitute for ginger, cinnamon and nutmeg[31][32][7][12][14]. A pinch of the powdered rhizome is used as a flovouring in tea[29]. The young and tender inflorescence is often eaten by children for its sweetness[31]. Young leaves - cooked[32]. The fresh leaves contain 0.078% oxalic acid[25]. The leaves can be used to flavour custards in the same way as vanilla pods[26]. The inner portion of young stems is eaten raw[35]. It makes a very palatable salad[14].

Product or use
Condiment
Plant part
Leaves
Plant part
Root
Plant part
Stem

Medicinal uses

Historical medicinal uses. These records describe reported uses. They do not establish safety or effectiveness. Ask a qualified health professional before using any plant medicinally.

This section contains historical Plants For A Future notes marked noncommercial.

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[31]. In Ayurveda it is highly valued as a rejuvenator for the brain and nervous system and as a remedy for digestive disorders[28]. However, some care should be taken in its use since some forms of the plant might be carcinogenic - see the notes above on toxicity for more information. The root is anodyne, aphrodisiac, aromatic, carminative, diaphoretic, emmenagogue, expectorant, febrifuge, hallucinogenic, hypotensive, sedative, stimulant, stomachic, mildly tonic and vermifuge[31][36][38][21][8][9][22][25][30]. It is used internally in the treatment of digestive complaints, bronchitis, sinusitis etc[24]. 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[28] and it is, therefore, recommended in the treatment of anorexia nervosa[26]. However if the dose is too large it will cause nausea and vomiting[K]. Sweet flag is also used externally to treat skin eruptions, rheumatic pains and neuralgia[24]. An infusion of the root can bring about an abortion[22] whilst chewing the root alleviates toothache[22]. It is a folk remedy for arthritis, cancer, convulsions, diarrhoea, dyspepsia, epilepsy etc. Chewing the root is said to kill the taste for tobacco[23]. Roots 2 - 3 years old are used since older roots tend to become tough and hollow[31]. They are harvested in late autumn or early spring and are dried for later use[31]. The dry root loses 70% of its weight, but has an improved smell and taste[26]. It does, however, deteriorate if stored for too long[26]. 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[16]. See also the notes above on toxicity. A homeopathic remedy is made from the roots[38]. It is used in the treatment of flatulence, dyspepsia, anorexia and disorders of the gall bladder[38].

Product or use
Abortifacient
Product or use
Anodyne
Product or use
Aphrodisiac
Product or use
Aromatic
Product or use
Carminative
Product or use
Diaphoretic
Product or use
Emmenagogue
Product or use
Febrifuge
Product or use
Hallucinogenic
Product or use
Homeopathy
Product or use
Odontalgic
Product or use
Sedative
Product or use
Stimulant
Product or use
Stomachic
Product or use
Tonic
Product or use
Vermifuge

Material uses

This section contains historical Plants For A Future notes marked noncommercial.

The leaves are used in basket making or woven into mats[10]. They have also been used as a thatch for roofs[31]. An essential oil from the rhizome is used in perfumery and as a food flavouring[1][5][33]. The oil is contained mainly in the outer skin of the root[27], it has a fragrance reminiscent of patchouli oil[16]. The fresh roots yield about 1.5 - 3.5% essential oil, dried roots about 0.8%[31][25]. Some plants from Japan have yielded 5% essential oil[31]. The essential oil is also an insect repellent and insecticide[23][29]. It is effective against houseflies[25]. When added to rice being stored in granaries it has significantly reduced loss caused by insect damage because the oil in the root has sterilized the male rice weevils[26]. An essential oil obtained from the leaves is used in perfumery and for making aromatic vinegars[27]. The leaves and the root have a refreshing scent of cinnamon[27]. All parts of plant can be dried and used to repel insects or to scent linen cupboards[37][6][34]. They can also be burnt as an incense[6], whilst the whole plant was formerly used as a strewing herb[31][6][4][24]. The growing plant is said to repel mosquitoes[18][20].

Product or use
Basketry
Product or use
Incense
Product or use
Insecticide
Product or use
Repellent
Product or use
Strewing
Product or use
Thatching
Product or use
Weaving

Environment

Range
Europe, Asia and N. America. Naturalized in Britain[11].
Habitat
Found in moist soils and shallow water in ditches, marshes, river edges and ponds[1][2][15][26].
Light
full sun
Shade tolerance
no shade
Water
aquatic
Hardiness
Zone 3+
Soil textures
sandy, loamy, clay
Soil pH
acid, neutral, alkaline
Tolerates Nutritionally Poor Soil
No
Drought
intolerant

Propagation

This section contains historical Plants For A Future notes marked noncommercial.

Seed - best sown in a cold frame as soon as it is ripe. Stand the pot in about 3cm of water. Pot up young seedlings as soon as they are large enough to handle, keep them wet by standing the pots in shallow water and overwinter for the first year in a greenhouse or cold frame. Seed is rarely produced in Britain[31][11]. Division in spring just before growth starts[1]. Very easy, it can be carried out successfully at any time in the growing season and can be planted direct into its permanent positions[K].

Cultivation

This section contains historical Plants For A Future notes marked noncommercial.

Prefers growing in shallow water or in a very moist loamy soil[19]. Requires a sunny position[19]. Prefers a pH in the range 5.5 to 7.5. Plants are hardy to about -25°c[15]. The sweet flag has a long history of use as a medicinal and culinary plant. It has been cultivated for this purpose but was more commonly allowed to naturalize and was then harvested from the wild. The plant seldom flowers or sets seed in Britain and never does so unless it is growing in water[31]. It can spread quite freely at the roots however and soon becomes established.

References

  1. F. Chittendon. RHS Dictionary of Plants plus Supplement. 1956 Oxford University Press 1951-00-00

    ↩1↩2↩3↩4

  2. Polunin. O. Flowers of Europe - A Field Guide. Oxford University Press 1969-00-00 ISBN 0192176218

    ↩

  3. Coon. N. The Dictionary of Useful Plants. Rodale Press 1975-00-00 ISBN 0-87857-090-x

    ↩

  4. Johnson. C. P. The Useful Plants of Great Britain.

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  5. Triska. Dr. Hamlyn Encyclopaedia of Plants. Hamlyn 1975-00-00 ISBN 0-600-33545-3

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  6. Holtom. J. and Hylton. W. Complete Guide to Herbs. Rodale Press 1979-00-00 ISBN 0-87857-262-7

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  7. Brouk. B. Plants Consumed by Man. Academic Press 1975-00-00 ISBN 0-12-136450-x

    ↩

  8. ? A Barefoot Doctors Manual. Running Press ISBN 0-914294-92-X

    ↩

  9. Mills. S. Y. The Dictionary of Modern Herbalism.

    ↩1↩2

  10. Buchanan. R. A Weavers Garden.

    ↩

  11. Clapham, Tootin and Warburg. Flora of the British Isles. Cambridge University Press 1962-00-00

    ↩1↩2

  12. Kunkel. G. Plants for Human Consumption. Koeltz Scientific Books 1984-00-00 ISBN 3874292169

    ↩

  13. Reid. B. E. Famine Foods of the Chiu-Huang Pen-ts'ao. Taipei. Southern Materials Centre 1977-00-00

    ↩1↩2

  14. Facciola. S. Cornucopia - A Source Book of Edible Plants. Kampong Publications 1990-00-00 ISBN 0-9628087-0-9

    ↩1↩2↩3

  15. Phillips. R. & Rix. M. Perennials Volumes 1 and 2. Pan Books 1991-00-00 ISBN 0-330-30936-9

    ↩1↩2

  16. Emboden. W. Narcotic Plants Studio Vista 1979-00-00 ISBN 0-289-70864-8

    ↩1↩2↩3

  17. Hedrick. U. P. Sturtevant's Edible Plants of the World. Dover Publications 1972-00-00 ISBN 0-486-20459-6

    ↩

  18. Riotte. L. Companion Planting for Successful Gardening. Garden Way, Vermont, USA. 1978-00-00 ISBN 0-88266-064-0

    ↩

  19. Huxley. A. The New RHS Dictionary of Gardening. 1992. MacMillan Press 1992-00-00 ISBN 0-333-47494-5

    ↩1↩2

  20. Allardice.P. A - Z of Companion Planting. Cassell Publishers Ltd. 1993-00-00 ISBN 0-304-34324-2

    ↩

  21. Lust. J. The Herb Book. Bantam books 1983-00-00 ISBN 0-553-23827-2

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  22. Weiner. M. A. Earth Medicine, Earth Food. Ballantine Books 1980-00-00 ISBN 0-449-90589-6

    ↩1↩2↩3

  23. Duke. J. A. and Ayensu. E. S. Medicinal Plants of China Reference Publications, Inc. 1985-00-00 ISBN 0-917256-20-4

    ↩1↩2↩3↩4

  24. Bown. D. Encyclopaedia of Herbs and their Uses. Dorling Kindersley, London. 1995-00-00 ISBN 0-7513-020-31

    ↩1↩2↩3↩4↩5

  25. Chopra. R. N., Nayar. S. L. and Chopra. I. C. Glossary of Indian Medicinal Plants (Including the Supplement). Council of Scientific and Industrial Research, New Delhi. 1986-00-00

    ↩1↩2↩3↩4

  26. Phillips. R. & Foy. N. Herbs Pan Books Ltd. London. 1990-00-00 ISBN 0-330-30725-8

    ↩1↩2↩3↩4↩5↩6

  27. Genders. R. Scented Flora of the World. Robert Hale. London. 1994-00-00 ISBN 0-7090-5440-8

    ↩1↩2↩3

  28. Chevallier. A. The Encyclopedia of Medicinal Plants Dorling Kindersley. London 1996-00-00 ISBN 9-780751-303148

    ↩1↩2↩3

  29. Manandhar. N. P. Plants and People of Nepal Timber Press. Oregon. 2002-00-00 ISBN 0-88192-527-6

    ↩1↩2

  30. Medicinal Plants in the Republic of Korea World Health Organisation, Manila 1998-00-00 ISBN 92 9061 120 0

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  31. Grieve. A Modern Herbal. Penguin 1984-00-00 ISBN 0-14-046-440-9

    ↩1↩2↩3↩4↩5↩6↩7↩8↩9↩10↩11↩12↩13

  32. Harris. B. C. Eat the Weeds. Pivot Health 1973-00-00

    ↩1↩2↩3

  33. Schery. R. W. Plants for Man.

    ↩1↩2

  34. Usher. G. A Dictionary of Plants Used by Man. Constable 1974-00-00 ISBN 0094579202

    ↩1↩2

  35. Elias. T. and Dykeman. P. A Field Guide to N. American Edible Wild Plants. Van Nostrand Reinhold 1982-00-00 ISBN 0442222009

    ↩1↩2

  36. Chiej. R. Encyclopaedia of Medicinal Plants. MacDonald 1984-00-00 ISBN 0-356-10541-5

    ↩1↩2

  37. Ceres. Free for All. Thorsons Publishers 1977-00-00 ISBN 0-7225-0445-4

    ↩

  38. Launert. E. Edible and Medicinal Plants. Hamlyn 1981-00-00 ISBN 0-600-37216-2

    ↩1↩2↩3

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