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Acorus

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Acorus
Sweet flagAcorus calamus- spadix
Scientific classificationEdit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Acorales
Reveal[1]
Family: Acoraceae
Martinov[1]
Genus: Acorus
L.
Synonyms

CalamusGarsault[2]

Acorusis agenusofmonocotflowering plants.This genus was once placed within the familyAraceae(aroids), but more recent classifications place it in its own familyAcoraceaeand orderAcorales,of which it is the sole genus of the oldest surviving line of monocots. Some older studies indicated that it was placed in a lineage (the order Alismatales), that also includes aroids (Araceae),Tofieldiaceae,and several families of aquatic monocots (e.g., Alismataceae,Posidoniaceae). However, modern phylogenetic studies demonstrate thatAcorusissisterto all other monocots. Common names includecalamusandsweet flag.

The genus is native toNorth Americaand northern and easternAsia,andnaturalisedin southern Asia andEuropefrom ancient cultivation.[2][3][4][5][6][7]The known wild populations arediploidexcept for sometetraploidsin eastern Asia, while the cultivated plants are steriletriploids,probably ofhybridorigin between the diploid and tetraploid forms.

Characteristics

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Habit ofAcorus calamus.

The inconspicuousflowersare arranged on a lateralspadix(a thickened, fleshy axis). Unlike aroids, there is nospathe(large bract, enclosing the spadix). The spadix is 4–10 cm long and is enclosed by the foliage. The bract can be ten times longer than the spadix. Theleavesare linear with entire margin.

Taxonomy

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Although the family Acoraceae was originally described in 1820, since thenAcorushas traditionally been included in Araceae in most classification systems, as in theCronquist system.The family has recently been resurrected as molecular systematic studies have shown thatAcorusis not closely related to Araceae or any othermonocotfamily, leading plant systematists to place the genus and family in its own order. This placement currently lacks support from traditional plant morphology studies, and some taxonomists still place it as a subfamily of Araceae, in the orderAlismatales.TheAPG IIIsystem recognizes order Acorales, distinct from the Alismatales, and as thesister groupto all other monocots. This relationship is confirmed by more recent phylogenetic studies.[8][9]Treatment in theAPG IV systemis unchanged from APG III.[10]

Species

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In older literature and on many websites, there is still much confusion, with the nameAcorus calamusequally but wrongfully applied toAcorus americanus(formerlyAcorus calamusvar.americanus).

As of July 2014, the Kew Checklist accepts only 2 species, one of which has three accepted varieties:[2]

  • Acorus calamusL.– common sweet flag; sterile triploid (3n= 36); probably of cultivated origin. It is native toEurope,temperateIndiaand theHimalayasand southernAsia,widely cultivated and naturalised elsewhere.
    • Acorus calamusvar.angustatusBesser- Siberia, China, Russian Far East, Japan, Korea, Mongolia, Himalayas, Indian Subcontinent, Indochina, Philippines, Indonesia
    • Acorus calamusvar.calamus- Siberia, Russian Far east, Mongolia, Manchuria, Korea, Himalayas; naturalized in Europe, North America, Java and New Guinea
  • Acorus americanusRaf.- Canada, northern United States, Buryatiya region of Russia
  • Acorus gramineusSol.exAiton– Japanese sweet flag or grassy-leaved sweet flag; fertile diploid (2n= 18); - China, Himalayas, Japan, Korea, Indochina, Philippines, Primorye

Acorusfrom Europe,Chinaand Japan have been planted in theUnited States.

Etymology

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The name 'acorus' is derived from the Greek word 'acoron', a name used byDioscorides,which in turn was derived from 'coreon', meaning 'pupil', because it was used inherbal medicineas a treatment forinflammationof theeye.[citation needed]

Distribution and habitat

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These plants are found inwetlands,particularly marshes, where they spread by means of thick rhizomes. Like many other marsh plants, they depend uponaerenchymato transport oxygen to the rooting zone.[11]They frequently occur on shorelines and floodplains where water levels fluctuate seasonally.

Ecology

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The native North American species appears in many ecological studies. Compared to other species of wetland plants, they have relatively high competitive ability.[12]Although many marsh plants accumulate large banks of buried seeds,[13]seed banks ofAcorusmay not accumulate in some wetlands owing to low seed production.[14]The seeds appear to be adapted to germinate in clearings; after a period of cold storage, the seeds will germinate after seven days of light with fluctuating temperature, and somewhat longer under constant temperature.[15]A comparative study of its life history traits classified it as a "tussock interstitial", that is, a species that has a dense growth form and tends to occupy gaps in marsh vegetation, not unlikeIris versicolor.[16]

Toxicity

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Sweet Flag (2006 drawing by USGS Northern Prairie Wildlife Research Center)

Products derived fromAcorus calamuswere banned in 1968 as food additives by the United StatesFood and Drug Administration.[17]The questionable chemical derived from the plant wasβ-asarone.Confusion exists whether all strains ofA. calamuscontain this substance.

Four varieties ofA. calamusstrains exist in nature: diploid, triploid, tetraploid and hexaploid.[18]Diploids do not produce the carcinogenic β-asarone. Diploids are known to grow naturally in Eastern Asia (Mongolia and C Siberia) and North America. The triploid cytotype probably originated in the Himalayan region, as a hybrid between the diploid and tetraploid cytotypes.[19]The North American Calamus is known asAcorus calamusvar.americanusor more recently as simplyAcorus americanus.Like the diploid strains ofA. calamusin parts of the Himalayas, Mongolia, and C Siberia, the North American diploid strain does not contain the carcinogenic β-asarone.[20][21][22]Research has consistently demonstrated that "β-asarone was not detectable in the North American spontaneous diploidAcorus[calamusvar.americanus] ".[23]

Uses

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The parallel-veined leaves of some species contain ethereal oils that give a sweet scent when dried. Fine-cut leaves used to be strewn across the floor in the Middle Ages, both for the scent, and for presumed efficacy againstpests.

References

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  1. ^abReveal, James L. (17 February 2011)."Indices Nominum Supragenericorum Plantarum Vascularium – S, Solanales".Indices Nominum Supragenericorum Plantarum Vascularium Alphabetical Listing by Genera of Validly Published Suprageneric Names.University of Maryland and Cornell University.
  2. ^abcKew World Checklist of Selected Plant Families[permanent dead link]
  3. ^Flora of North America:Acorus
  4. ^Flora of China, Vol. 23 Page 1,Xương bồ chúcchang pu shu,AcorusLinnaeus, Sp. Pl. 1: 324. 1753.
  5. ^Govaerts, R. & Frodin, D.G. (2002). World Checklist and Bibliography of Araceae (and Acoraceae): 1–560. The Board of Trustees of the Royal Botanic Gardens, Kew.
  6. ^Boyce, P.C., Sookchaloem, D., Hetterscheid, W.L.A., Gusman, G., Jacobsen, N., Idei, T. & Nguyen, V.D. (2012). Flora of Thailand 11(2): 101–325. The Forest Herbarium, National Park, Wildlife and Plant Conservation Department, Bangkok.
  7. ^Nooteboom, H.P. (ed.) (2011). Flora Malesiana 20: 1–61. Noordhoff-Kolff N.V., Djakarta.
  8. ^Soltis et al 2011.
  9. ^Givnish et al 2010.
  10. ^Angiosperm Phylogeny Group (2016)."An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV".Botanical Journal of the Linnean Society.181(1): 1–20.doi:10.1111/boj.12385.
  11. ^Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. Chapter 1.
  12. ^Gaudet, C.L.; Keddy, P.A. (1988). "Predicting competitive ability from plant traits: a comparative approach".Nature.334(6179): 242–243.doi:10.1038/334242a0.S2CID4284026.Figure 1.
  13. ^van der Valk, A. G.; Davis, C. B. (1978)."The role of seed banks in the vegetation dynamics of prairie glacial marshes".Ecology.59(2): 322–35.doi:10.2307/1936377.JSTOR1936377.
  14. ^Leck, Mary Allessio; Simpson, Robert L. (1995)."Ten-year seed bank and vegetation dynamics of a tidal freshwater marsh"(PDF).American Journal of Botany.82(12): 1547–1557.doi:10.2307/2446183.hdl:2027.42/141113.JSTOR2446183.
  15. ^Shipley, B.; Keddy, P.A.; Moore, D.R.J.; Lemky, K. (1990). "Regeneration and establishment strategies of emergent macrophytes".Journal of Ecology.77(4): 1093–1110.doi:10.2307/2260825.JSTOR2260825.Appendix 3.
  16. ^Boutin, C.; Keddy, P. A. (1993). "A functional classification of wetland plants".Journal of Vegetation Science.4(5): 591–600.doi:10.2307/3236124.JSTOR3236124.Figure 2
  17. ^"Code of Federal regulations, title 21".
  18. ^Ginwal, HS, An efficient genomic DNA isolation protocol for RAPD and SSR analysis inAcorus calamusL.
  19. ^Evstatieva et al., Fitologiya 48: 19–22. 1996; Löve & Löve,Proc. Genet. Soc. Canada2: 14–17. 1957
  20. ^Marongiu, L.B; Piras, A; Porcedda, S (2005). "Chemical composition of the essential oil and supercritical CO2 extract of Commiphora myrrha (Nees) Engl. and ofAcorus calamus".Journal of Agricultural and Food Chemistry.53(20): 7939–43.doi:10.1021/jf051100x.PMID16190653.
  21. ^(Rost and Bos, 1979)
  22. ^Antimicrobial activities of the crude methanol extract ofAcorus calamusLinn., S Phongpaichit, N Pujenjob, J. Songklanakarin
  23. ^Radušienė, J.; Judžentienė, A.; Pečiulytė, D.; Janulis, V. (2007). "Essential oil composition and antimicrobial assay of Acorus calamus leaves from different wild populations".Plant Genetic Resources.5:37–44.doi:10.1017/S1479262107390928.S2CID86085313.

Bibliography

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Wikisourcehas the text of the 1905New International Encyclopediaarticle "Acorus".
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