Acorus calamus

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Sweet flag redirects here. For other uses see sweet flag (disambiguation)
Common Sweet Flag
Acorus calamus1.jpg
Sweet flag
Conservation status
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Monocots
Order: Acorales
Family: Acoraceae
Genus: Acorus
Species: A. calamus
Binomial name
Acorus calamus
L., 1753

Acorus calamus (also called Sweet Flag or Calamus, among many common names[2]) is a tall perennial wetland monocot of the Acoraceae family, in the genus Acorus. In spite of common names that include the words "rush" and "sedge," it is neither a rush nor sedge.[3] The scented leaves and more strongly scented rhizomes have traditionally been used medicinally and to make fragrances, and the dried and powdered rhizome has been used as a substitute for ginger, cinnamon and nutmeg.[3][4]

Names[edit]

In addition to "sweet flag" and "calamus" other common names include beewort, bitter pepper root, calamus root, flag root, gladdon, myrtle flag, myrtle grass, myrtle root, myrtle sedge, pine root, rat root, sea sedge, sweet cane, sweet cinnamon, sweet grass, sweet myrtle, sweet root, sweet rush, and sweet sedge.[2] Common names in Asia include: "shoubu 菖蒲," in Japanese, "vacha"; "bacch" (Unani); "bajai," "gora-bach," "vasa bach" (Hindi); "vekhand" (Marathi); "vashambu" (Tamil); "vadaja," "vasa" (Telugu); "baje" (Kannada); "vayambu" (Malayalam); Haimavati, "bhutanashini," "jatila" (Sanskrit).[3]

Etymology[edit]

The generic name is the Latin word acorus is derived from the Greek άχόρου (áchórou) of Dioscorides (note different versions of the text have different spellings). The word άχόρου itself is thought to have been derived from the word κόρη (kóri), which means pupil (of an eye), due to the juice from the root of the plant being used as a remedy in diseases of the eye ('darkening of the pupil').[5][6][7]

The specific name calamus (meaning "cane") is derived from Greek ΚΆΛΑΜΟΣ (kálamos, meaning "reed"), which is cognate to Latin culmus (meaning "stalk") and Old English healm (meaning "straw"), and derived from Proto-Indo European *kole-mo- (thought to mean "grass" or "reed"). The Arabic word قَلَم (qálam, meaning "pen") and Sanskrit कलम (kaláma, meaning "reed used as a pen", and a sort of rice) are thought to have been borrowed from Greek.[8][9][10][11]

The name sweet flag refers to its sweet scent and its similarity to Iris species, which are commonly known as flags in English since the late fourteenth century.[12][13]

Botanical information[edit]

There are three cytotypic forms distinguished by chromosome number: a diploid form (2n=24), an infertile triploid form (2n=36), and a tetraploid form (see below). The triploid form is the most common and is thought to have arisen relatively recently in the Himalayan region through hybridisation of the diploid with the tetraploid.[14]

Probably indigenous to most of Asia, the triploid form Acorus calamus var. calamus (also known as var. vulgaris or var. verus) has now been introduced across Europe, Australia, New Guinea, South Africa, Réunion and North America.[3][4][14][15][16][17][18][19] The tetraploid form Acorus calamus var. angustatus is native throughout Asia, from India to Japan and the Philippines and from Indonesia to Siberia.[15] The diploid form Acorus americanus or Acorus calamus var. americanus is found in northern subarctic North America and scattered disjunct areas throughout the Mississippi Valley, and furthermore diploids are also found in Mongolia, central Siberia (Buryatia), Gilgit–Baltistan in Pakistan (claimed by India) and northern Himachal Pradesh in India. It is extinct in some parts of the United States and Canada. It may not have been native to some of these areas, Pre-Columbian populations are thought to have dispersed it across parts of the United States.[15][20][21][22]

Currently the taxonomic position of these forms is contested. The comprehensive taxonomic analysis in the Kew World Checklist of Selected Plant Families from 2002 considers all three forms to be distinct varieties of a single species.[15][23] Sue A. Thompson in her 1995 Phd dissertation and in her 2000 entry in the Flora of North America considers the diploid form to a distinct species. Note Thompson only analyses North American forms of the diploid variety in her treatment, and does not analyse the morphology of Asian forms of the diploid variety. Also note that in older USA literature the name Acorus americanus may be used indiscriminately for all forms of Acorus calamus occurring in North America, irrespective of cytological diversity (i.e. both the diploid and triploid forms).[20] The recent treatment in the Flora of China from 2010, which is followed in the Tropicos database system, considers all varieties to be synonyms of a single taxonomically undifferentiated species, pointing to morphological overlap in the characteristics singled out by Thompson.[14][24]

According to Thompson the primary morphological distinction between the triploid and the North American forms of the diploid is made by the number of prominent leaf veins, the diploid having a single prominent midvein with on both sides of this equally raised secondary veins, the triploid having a single prominent midvein with the secondary veins barely distinct. Thompson notes a number of other details which she claims can be used to tell the different forms apart in North America, such as flower length, average maximum leaf length, relative length of the sympodial leaf with respect to the vegetative leaves, the average length of the spadix during flowering, and tendency of the leaf margin to undulate in the triploid. She notes that many of these characteristics overlap, but that in general the triploid is somewhat larger and more robust on average than most North American forms of the diploid. According to Heng Li, Guanghua Zhu and Josef Bogner in the Flora of China there is clear overlap in these characteristics and the different cytotypes are impossible to distinguish morphologically.[14][20]

Triploid plants are infertile and show an abortive ovary with a shrivelled appearance. This form will never form fruit (let alone seeds) and can only spread asexually.[20]

The tetraploid variety is usually known as Acorus calamus var. angustatus Besser. A number of synonyms are known, but a number are contested as to which variety they belong. It is morphologically diverse, with some forms having very broad and some narrow leaves. It is furthermore also cytotypically diverse, with an array of different karyotypes.[15][22][25]

A further hexaploid form exists in central and northwestern Yunnan and Kashmir. This form has not been given taxonomic status. At least 3 different karyotypes have been classified as hexaploid; 2n=66in Yunnan and 2n=54 and 2n=72 in Kashmir.[22][25]

Diploid plants in North America apparently produce no or only trace amounts of b-asarone. According to one study, triploids produce a small amount, constituting around 0.3% of the rhizome in crude content, whereas tetraploids may be found in at least two chemotypes, one with 2.0%, and one with 4.0 to 8.0%.[26]

Uses[edit]

A. Calamus has been an item of trade in many cultures for thousands of years. It has been used medicinally for a wide variety of ailments, and its aroma makes calamus essential oil valued in the perfume industry. The essence from the rhizome is used as a flavor for pipe tobacco. When eaten in crystallized form, it is called "German ginger". In Europe Acorus calamus was often added to wine, and the root is also one of the possible ingredients of absinthe. It is also used in bitters.[4] In Lithuania Ajeras (Sweet flag) is added to home baked black bread.

History[edit]

Although probably not native to Egypt, this plant was already mentioned in the Chester Beatty papyrus VI dating to approximately 1300 BC. The ancient Egyptians rarely mentioned the plant in medicinal contexts (the afore-mentioned papyrus mentioned using it in conjunction with several ingredients as a bandage used to sooth an ailment of the stomach), but it was certainly used to make perfumes.[27]

Initially Europeans confused the identity and medicinal uses of the Acorus calamus of the Romans and Greeks with their native Iris pseudacorus. Thus the Herbarius zu Teutsch, published at Mainz in 1485, describes and includes a woodcut of this iris under the name Acorus. This German book is one of three possible sources for the French Le Grant Herbier, written in 1486, 1488, 1498 or 1508, of which an English translation was published as the Grete Herball by Peter Treveris in 1526, all containing the false identification of the Herbarius zu Teutsch.[28] William Turner, writing in 1538, describes 'acorum' as "gladon or a flag, a yelowe floure delyce".[29]

The plant was introduced to Britain in the late 16th century. By at least 1596 true Acorus calamus was grown in Britain, as it is listed in The Catalogue, a list of plants John Gerard grew in his garden at Holborn. Gerard notes "It prospereth exceeding well in my garden, but as yet bearth neither flowers nor stalke". Gerard lists the Latin name as Acorus verus, but it is evident there was still doubt about its veracity: in his 1597 herbal he lists the English common name as 'bastard calamus'.[30]

Cultural uses[edit]

In Britain the plant was also cut for use as a sweet smelling floor covering for the packed earth floors of medieval dwellings and churches, and stacks of rushes have been used as the centrepiece of rushbearing ceremonies for many hundreds of years.[31] It has also been used as a thatching material for English cottages.[32]

In modern Egypt it is thought to have aphrodisiac properties.[27]

For the Penobscot people this was a very important root. One story goes that a sickness was plaguing the people. A muskrat spirit came to a man in dream, telling him that he (the muskrat) was a root and where to find him. The man awoke, found the root, and made a medicine which cured the people. In Penobscot homes, pieces of the dried root were strung together and hung up for preservation. Steaming it throughout the home was thought to "kill" sickness. While travelling, a piece of root was kept and chewed to ward off illness.[33]

Teton-Dakota warriors chewed the root to a paste, which they rubbed on their faces. It was thought to prevent excitement and fear when facing an enemy.[33]

The Potawatomi people powdered the dried root and placed this up the nose to cure catarrh.[33]

Illustration from an 1885 flora

Herbal medicine[edit]

Sweet flag has a very long history of medicinal use in Chinese and Indian herbal traditions.[34] The leaves, stems, and roots are used in various Siddha and Ayurvedic medicines.[35] It is widely employed in modern herbal medicine as its sedative, laxative, diuretic, and carminative properties.[4] It is used in Ayurveda to counter the side effects of all hallucinogens.[36] Sweet Flag, known as "Rat Root" is one of the most widely and frequently used herbal medicines amongst the Chipewyan people.[37]

Hallucinogenic properties[edit]

Chewing the rootstock of the plant can cause visual hallucinations, possibly due to the presence of alpha-asarone or beta-asarone.[38]

Horticulture[edit]

This plant is sometimes used as a pond plant in horticulture.[39] There is at least one ornamental cultivar known, it is usually called 'Variegatus',[40] but the RHS recommends calling it 'Argenteostriatus'.[41]

Modern Research[edit]

Acorus calamus shows neuroprotective effect against stroke and chemically induced neurodegeneration in rats. Specifically, it has protective effect against acrylamide induced neurotoxicity.[42]

Both roots and leaves of A. calamus have shown antioxidant,[43] antimicrobial and insecticidal activities.[3]

Acorus calamus may prove to be an effective control measure against cattle tick, Rhipicephalus (Boophilus) microplus.[44]

A recent study showed that beta-asarone isolated from Acorus calamus oil inhibits adipogenesis in 3T3-L1 cells and thus reduces lipid accumulation in fat cells.[45]

Chemistry[edit]

Both triploid and tetraploid A. calamus contain alpha-asarone.[4] Other phytochemicals include:

Diploids do not contain beta-asarone (β-asarone).[50]

Cultural symbolism[edit]

The calamus has long been a symbol of love. The name is associated with a Greek myth: Kalamos, son of the river-god Maeander, who loved the youth Karpos, of Zephyrus (the West Wind) and Chloris (Spring). When Karpos drowned in a swimming race, Kalamos also drowned and was transformed into a reed, whose rustling in the wind was interpreted as a sigh of lamentation.

The plant was a favorite of Henry David Thoreau (who called it "sweet flag"), and also of Walt Whitman, who added a section called the "Calamus" poems, to the third edition of Leaves of Grass (1860). In the poems the calamus is used as a symbol of love, lust, and affection.

The root of the calamus (Tamil vasambu வசம்பு) is cut into disc-shaped beads, and made into bracelets, which are typically worn by newborns for the first few months. A vasambu bracelet is a symbol of a newborn baby in Tamil culture.

Safety and Regulations[edit]

A. calamus and products derived from A. calamus (such as its oil) were banned in 1968 as food additives and medicines by the United States Food and Drug Administration.[51] The FDA ban was the result of lab studies that involved supplementing the diets of lab animals over a prolonged period of time with massive doses of isolated chemicals (β-asarone) from the Indian Jammu strain of calamus. The animals developed tumors, and the plant was labeled procarcinogenic.[52][53] Wichtl says "It is not clear whether the observed carcinogenic effects in rats are relevant to the human organism."[54] However, most sources advise caution in ingesting strains other than the diploid strain.

In reality β-asarone is not actually a carcinogen but it is a procarcinogen that is neither hepatotoxic nor directly hepatocarcinogenic. It must first undergo metabolic l'-hydroxylation in the liver before achieving toxicity. Cyrochrome P450 in the hepatocytes is responsible for secreting the hydrolyzing enzymes that convert β-asarone into genotoxic epoxide structure.[55] Even with the activation of these metabolites, the carcinogenic potency is very low due to the rapid breakdown of epoxide residues with hydrolase which leaves these compounds inert (Luo, 1992).[citation needed] Additionally, the major metabolite of β-asarone is 2,4,5-trimethoxycinnamic acid, a derivative which is not a carcinogen (Hasheminejad & Caldwell, 1999).

Notes and references[edit]

  1. ^ Lansdown, R.V. (2014). "Acorus calamus". IUCN Red List of Threatened Species. Version 2014.2. International Union for Conservation of Nature. Retrieved 28 August 2014. 
  2. ^ a b Sylvan T. Runkel, Alvin F. Bull (1979, 2009). Wildflowers of Iowa Woodlands. Iowa City, Iowa: University of Iowa Press. p. 119. Retrieved 13 December 2011. 
  3. ^ a b c d e Balakumbahan, R.; K. Rajamani; K. Kumanan (29 December 2010). "Acorus calamus: An overview". Journal of Medicinal Plants Research 4 (25): 2740–2745. Retrieved 14 May 2011. 
  4. ^ a b c d e f Gualtiero Simonetti (1990). Stanley Schuler, ed. Simon & Schuster's Guide to Herbs and Spices. Simon & Schuster, Inc. ISBN 0-671-73489-X. 
  5. ^ Pliny the Elder; The Natural History, book 25, chapter 100; http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/25*.html
  6. ^ Dioscorides, Pedanius; Περὶ ὕλης ἰατρικῆς (De Materia Medica), Ch. 2, pg. 11; 50-70; translation by Sprengel, Karl Philipp; 1829
  7. ^ http://www.scientificlatin.org/philbot/pb240.html
  8. ^ Monier Williams Sanskrit-English Dictionary; Cologne Digital Sanskrit Dictionaries; http://www.sanskrit-lexicon.uni-koeln.de/cgi-bin/monier/serveimg.pl?file=/scans/MWScan/MWScanjpg/mw0260-karSaphala.jpg
  9. ^ Liddell, Henry George and Scott, Robert; A Greek-English Lexicon, κάλα^μος; Oxford University Press; 1925; http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.04.0057:entry=ka/lamos&highlight=acorus
  10. ^ Harper, Douglas; Online Etymological Dictionary; http://www.etymonline.com/index.php?term=shawm; accessed 9 July 2013
  11. ^ Avadhani, Mythili et al.; The Sweetness and Bitterness of Sweet Flag [Acorus calamus L.] – A Review; Research Journal of Pharmaceutical, Biological and Chemical Sciences, Volume 4, Issue 2, Page No. 598; April–June 2013; http://www.rjpbcs.com/pdf/2013_4%282%29/%5B67%5D.pdf
  12. ^ Harper, Douglas; Online Etymological Dictionary; http://www.etymonline.com/index.php?term=flag&allowed_in_frame=0
  13. ^ http://www.rook.org/earl/bwca/nature/aquatics/acorus.html
  14. ^ a b c d Heng, Li (李恒), Guanghua, Zhu (朱光华); and Bogner, Josef; Flora of China, Vol. 23, Acoraceae; Science Press & Missouri Botanical Garden; Beijing & St. Louis; 2010; accessed at http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200027130
  15. ^ a b c d e Govaerts, R.; World Checklist of Selected Plant Families: Royal Botanic Gardens, Kew; 2002; http://apps.kew.org/wcsp/namedetail.do?name_id=2309; accessed 9 July 2013
  16. ^ African Plant Database, Acorus calamus; Conservatoire et Jardin botaniques & South African National Biodiversity Institute; last modified 2007-02-14; http://www.ville-ge.ch/musinfo/bd/cjb/africa/details.php?langue=an&id=30524; accessed 9 July 2013
  17. ^ Euro+Med Plantbase; http://ww2.bgbm.org/EuroPlusMed/PTaxonDetail.asp?NameId=77936&PTRefFk=8000000; accessed 9 July 2013
  18. ^ Randall, R.P.; The introduced flora of Australia and its weed status; CRC for Australian Weed Management; Glen Osmond; September 2007; accessed at http://www.agric.wa.gov.au/objtwr/imported_assets/content/hort/intro_flora_australia.pdf
  19. ^ Index de la flore vasculaire de la Réunion; http://www.tela-botanica.org/eflore/BDNFM/2006.01/nn/118; accessed 9 July 2013
  20. ^ a b c d Thompson, Sue A.; Flora of North America, Acorus; 2000; http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=100307
  21. ^ Gilmore, Melvin R., Dispersal By Indians a Factor in the Extension of Discontinuous Distribution of Certain Species of Native Plants, Papers of the Michigan Academy of Science, Arts, and Letters 13 (1931): 89–94; http://triscience.com/General/dispersal-by-indians-a-factor-in-the-extension-of-discontinuous-distribution-of-certain-species-of-native-plants/doculite_view
  22. ^ a b c Ogra, R. K. et al.; Indian calamus (Acorus calamus L.): not a tetraploid; Current Science, Vol. 97, No. 11, 10 December 2009; Current Science Association; Bangalore; http://www.currentscience.ac.in/Downloads/article_id_097_11_1644_1647_0.pdf
  23. ^ The Plant List; http://www.theplantlist.org/tpl/search?q=acorus+calamus; accessed 9 July 2013
  24. ^ Tropicos; Missouri Botanical Garden; http://www.tropicos.org/NameSearch.aspx?name=Acorus+calamus&commonname=; accessed 9 July 2013
  25. ^ a b Hong, Wang, Wenli, Li, Zhijian, Gu and Yongyan, Chen; Cytological study on Acorus L. in southwestern China, with some cytogeographical notes on A. calamus; Acta Botanica Sinica, 2001, 43(4):354-358; http://europepmc.org/abstract/CBA/348223/reload=0;jsessionid=tdWTGuYlZomEXqtMfwaO.6
  26. ^ http://www.ncbi.nlm.nih.gov/pubmed/17402025
  27. ^ a b Manniche, Lisa; An Ancient Egyptian Herbal, pg. 74; American University in Cairo Press; Cairo; 2006; ISBN 977 416 034 7
  28. ^ Rohde, Eleanour Sinclair; The Old English Herbals; Longmans, Green and Co.; 1922; accessed at http://www.gutenberg.org/files/33654/33654-h/33654-h.htm
  29. ^ Turner, William; Libellus de re herbaria, pg. Aii; 1538; in Jackson, Benjamin Daydon; Libellus de re herbaria novus, by William Turner, originally pub. in 1538, reprinted in facsimile, pg. 36; private print; London; 1877; accessed at http://archive.org/stream/libellusdereherb00turn#page/n36/mode/1up
  30. ^ Jackson, Benjamin Daydon; A catalogue of plants cultivated in the garden of John Gerard, pg. 1, 23; private printing; London; 1876; accessed at http://archive.org/details/mobot31753002733357
  31. ^ Hüsken, Wim N. M (1996), "Rushbearing:a forgotten British custom", English parish drama., p. 17, ISBN 90-420-0060-0 
  32. ^ Hirsch, Pamela; Gladstar, Rosemary (2000). Planting the future: saving our medicinal herbs. Rochester, Vt: Healing Arts Press. p. 85. ISBN 0-89281-894-8. 
  33. ^ a b c Erichsen-Brown, Charlotte (1989). Medicinal and Other Uses of North American Plants: A Historical Survey with Special Reference to the Eastern Indian Tribes. Dover Publications. pp. 231–232. ISBN 978-0-486-25951-2. 
  34. ^ Mukherjee P.K., Kumar V., Mal M., Houghton P.J. "Acorus calamus: Scientific validation of ayurvedic tradition from natural resources"Pharmaceutical Biology 2007 45:8 (651–666)
  35. ^ "Vasambu". Tamilnadu.com. 1 April 2013. 
  36. ^ Dr. Vasant K. Lad, Ayurveda: The Science of Self-Healing
  37. ^ Johnson, Derek; Linda Kershaw; Andy MacKinnon; Jim Pojar (1995). Plants of the Western Boreal Forest & Aspen Parkland. Lone Pine Publishing. ISBN 1-55105-058-7. 
  38. ^ Schultes, Richard Evans. A golden guide to hallucinogenic plants. New York: Golden Press. p. 73. ISBN 0307243621. 
  39. ^ Oudhia, P. (2002).Rice-Acorus intercropping: a new system developed by innovative farmers of Chhattisgarh (India).International Rice Research Notes.27 (1):56.
  40. ^ Missouri Botanical Garden; http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/plant-finder/plant-details/kc/a634/acorus-calamus-variegatus.aspx; accessed 9 July 2013
  41. ^ Royal Horticultural Society; http://apps.rhs.org.uk/plantselector/plant?plantid=56; accessed 9 July 2013
  42. ^ Shukla PK, Khanna VK, Ali MM, Maurya R, Khan MY, Srimal RC. "Neuroprotective effect of Acorus calamus against middle cerebral artery occlusion-induced ischaemia in rat" Hum Exp Toxicology (April 2006) 25(4):187-94. PMID 16696294;Shukla PK, Khanna VK, Ali MM, Maurya RR, Handa SS, Srimal RC. "Protective effect of acorus calamus against acrylamide induced neurotoxicity" Phytother Res. (May 2002) 16(3):256-60. PMID 12164272
  43. ^ S. Asha Devi; Deepak Ganjewala, "Antioxidant Activities of Methanolic Extracts of Sweet-Flag (Acorus calamus) Leaves and Rhizomes" Journal of Herbs, Spices & Medicinal Plants Volume 17, Issue 1, 2011, Pages 1 – 11
  44. ^ Ghosh S, Sharma AK, Kumar S, Tiwari SS, Rastogi S, Srivastava S, Singh M, Kumar R, Paul S, Ray DD, Rawat AK "In vitro and in vivo efficacy of Acorus calamus extract against Rhipicephalus (Boophilus) microplus." Parasitol Res. 2011 Feb;108(2):361-70
  45. ^ Meng-Hwan Lee, , Yun-Yu Chen, , Jung-Wei Tsai,Sheue-Chi Wang, Takashi Watanabe and Ying-Chieh Tsai, Inhibitory effect of β-asarone, a component of Acorus calamus essential oil, on inhibition of adipogenesis in 3T3-L1 cells. Food ChemistryVolume 126, Issue 1, 1 May 2011, Pages 1–7. doi:10.1016/j.foodchem.2010.08.052
  46. ^ Streloke, M. et al.; Ascher, K. R. S.; Schmidt, G. H.; Neumann, W. P. (1989). "Vapor pressure and volatility of β-asarone, the main ingredient of an indigenous stored-product insecticide, Acorus calamus oil". Phytoparasitica 17 (4): 299–313. doi:10.1007/BF02980759. 
  47. ^ Paneru, R.B. et al.; Lepatourel, G; Kennedy, S (1997). "Toxicity of Acorus calamus rhizome powder from Eastern Nepal to Sitophilus granarius (L.) and Sitophilus oryzae (L.) (Coleoptera, Curculionidae)". Crop Protection 16 (8): 759–763. doi:10.1016/S0261-2194(97)00056-2. 
  48. ^ Marongiu, Bruno et al.; Piras, Alessandra; Porcedda, Silvia; Scorciapino, Andrea (2005). "Chemical Composition of the Essential Oil and Supercritical CO2 Extract of Commiphora myrrha (Nees) Engl. and of Acorus calamus L.". Journal of Agricultural and Food Chemistry 53 (20): 7939–7943. doi:10.1021/jf051100x. 
  49. ^ Raina, V. K. et al.; Srivastava, S. K.; Syamasunder, K. V. (2003). "Essential oil composition of Acorus calamus L. from the lower region of the Himalayas". Flavour and Fragrance Journal 18 (1): 18–20. doi:10.1002/ffj.1136. 
  50. ^ Essential oil composition and antimicrobial assay of Acorus calamus leaves from different wild populations, J Radušienė, A Judžentienė… – Plant Genetics, 2007 – Cambridge Univ Press, 1982; Lander and Schreier, 1990
  51. ^ {{cite web url=http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=189.110 |title=Code of Federal regulations, title 21}}
  52. ^ http://www.herbcraft.org/calamus.html
  53. ^ Natural carcinogenic products, EK Weisburger – Environmental Science & Technology, 1979 – ACS Publications
  54. ^ Wichtl, Max,Herbal drugs and phytopharmaceuticals: a handbook,2004
  55. ^ American Herbal Products Association's botanical safety handbook, By American Herbal Products Association, Michael McGuffin

External links[edit]