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Dioscorea

{{short description|Genus of yams}}

{{Automatic taxobox

| image = Dioscorea balcanica BotGardBln310505.jpg

| image_caption = Dioscorea balcanica

| taxon = Dioscorea

| authority = L.

| subdivision_ranks = Sections

| subdivision =

  • Botryosicyos
  • Combilium
  • Enantiophyllum
  • Lasiophyton
  • Macroura
  • Macrourae
  • Macrogynodium
  • Opsophyton
  • Euopsophyton
  • Shannicorea
  • Stenophora

(Not all are supported by molecular analyses.{{cite journal |last1=Couto |first1=Ricardo S |last2=Martins |first2=Aline C |last3=Bolson |first3=Mônica |last4=Lopes |first4=Rosana C |last5=Smidt |first5=Eric C |last6=Braga |first6=João Marcelo A |title=Time calibrated tree of Dioscorea (Dioscoreaceae) indicates four origins of yams in the Neotropics since the Eocene |journal=Botanical Journal of the Linnean Society |date=28 September 2018 |volume=188 |issue=2 |pages=144–160 |doi=10.1093/botlinnean/boy052 |doi-access=free}} See tropicos query cited for more.{{cite web |title= Name - Dioscorea L. (Subgeneric subordinate taxa) |url=http://legacy.tropicos.org/NamePage.aspx?nameid=40031872&tab=subordinatetaxa |website=legacy.tropicos.org}})

| synonyms_ref =

| synonyms =

  • Tamus L.
  • Ricophora Mill.
  • Tamnus Mill.
  • Oncus Lour.
  • Ubium J.F.Gmel.
  • Oncorhiza Pers.
  • Testudinaria Salisb. ex Burch.
  • Rhizemys Raf.
  • Botryosicyos Hochst.
  • Helmia Kunth
  • Sismondaea Delponte
  • Epipetrum Phil.
  • Borderea Miégev.
  • Elephantodon Salisb.
  • Hamatris Salisb.
  • Merione Salisb.
  • Polynome Salisb.
  • Strophis Salisb.
  • Higinbothamia Uline
  • Nanarepenta Matuda
  • Hyperocarpa (Uline) G.M.Barroso, E.F.Guim. & Sucre

}}

Dioscorea is a genus of over 600 species of flowering plants in the family Dioscoreaceae, native throughout the tropical and warm temperate regions of the world. The vast majority of the species are tropical, with only a few species extending into temperate climates.{{Cite web|url=http://apps.kew.org/wcsp/namedetail.do?name_id=239724|title=World Checklist of Selected Plant Families: Royal Botanic Gardens, Kew|website=apps.kew.org|language=en-GB|access-date=2017-01-23}}Govaerts, R., Wilkin, P. & Saunders, R.M.K. (2007). World Checklist of Dioscoreales. Yams and their allies: 1-65. The Board of Trustees of the Royal Botanic Gardens, Kew.Wilkin, P. & Thapyai, C. (2009). Flora of Thailand 10(1): 1-140. The Forest Herbarium, National Park, Wildlife and Plant Conservation Department, Bangkok.{{Cite web|url=http://luirig.altervista.org/flora/taxa/index1.php?scientific-name=dioscorea+communis|title=Dioscorea communis [Tamaro]|website=luirig.altervista.org|language=it|access-date=2017-01-23}} It was named by the monk Charles Plumier after the ancient Greek physician and botanist Dioscorides.

Description

They are tuberous herbaceous perennial lianas, growing to {{convert|2–12|m|ft}} or more tall. The leaves are spirally arranged, mostly broad heart-shaped. The flowers are individually inconspicuous, greenish-yellow, with six petals; they are mostly dioecious, with separate male and female plants, though a few species are monoecious, with male and female flowers on the same plant. The fruit is a capsule in most species, a soft berry in a few species.{{Cite web|url=http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=110295|title=Dioscorea in Flora of North America @ efloras.org|website=www.efloras.org|access-date=2017-01-23}}{{Cite web|url=http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=110295|title=Dioscorea in Flora of China @ efloras.org|website=www.efloras.org|access-date=2017-01-23}}

Most Dioscorea species that have been examined possess extrafloral nectaries at the petiole or leaf underside.{{cite journal |date=2012-10-18 |first1=Marjorie G. |last1=Weber |first2=Kathleen H. |last2=Keeler |title=The phylogenetic distribution of extrafloral nectaries in plants |pages=1251–1261 |doi=10.1093/aob/mcs225 |journal=Annals of Botany |eissn=1095-8290 |volume=111 |issue=6|pmid=23087129 |pmc=3662505 }}

Cultivation and uses

Several species, known as yams, are important agricultural crops in tropical regions, grown for their large tubers. Many of these are toxic when fresh, but can be detoxified and eaten, and are particularly important in parts of Africa, Asia, and Oceania.

One class of toxins found in many species is steroidal saponins, which can be converted through a series of chemical reactions into steroid hormones for use in medicine and as contraceptives.

The 1889 book "The Useful Native Plants of Australia" records that Dioscorea hastifolia is "One of the hardiest of the yams. The tubers are largely consumed by the local aborigines for food. (Mueller)."{{cite book | author=J. H. Maiden | year=1889 | title=The useful native plants of Australia : Including Tasmania | publisher= Turner and Henderson, Sydney | url=https://primo-slnsw.hosted.exlibrisgroup.com/primo-explore/fulldisplay?docid=SLNSW_ALMA21105097830002626&context=L&vid=SLNSW&search_scope=EEA&tab=default_tab&lang=en_US}}

Accepted species <small>(613)</small>, subspecies, and varieties

{{cleanup section|reason=May be more useful to arrange by section, however unreliable molecularly they can be|date=October 2021}}

The genus includes the following species and subspecies:{{citation needed|date=February 2016}}

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The closely related genus Tamus is included in Dioscorea by some sources,{{Citation |title=World Checklist of Selected Plant Families |publisher=The Board of Trustees of the Royal Botanic Gardens, Kew |url=http://apps.kew.org/wcsp/home.do |access-date=2011-05-28 }}, search for "Tamus" but is maintained as distinct by others.{{Citation |last=Stace |first=Clive |author-link = Clive Stace |year=2010 |title=New Flora of the British Isles |edition=3rd |location=Cambridge, UK |publisher=Cambridge University Press |isbn=978-0-521-70772-5 }}, p. 854 For Dioscorea communis (L.) Caddick & Wilkin, see Tamus communis.

See also

References

{{Reflist}}

Bibliography

{{Commons category|Dioscorea}}

{{Wikispecies|Dioscorea}}

{{Refbegin}}

  • [http://rbg-web2.rbge.org.uk/cgi-bin/nph-readbtree.pl/feout?FAMILY_XREF=&GENUS_XREF=Dioscorea&SPECIES_XREF=&TAXON_NAME_XREF=&RANK= Flora Europaea: Dioscorea]
  • [http://www.efloras.org/florataxon.aspx?flora_id=5&taxon_id=110295 Flora of Pakistan: Dioscorea]
  • Schols, P. 2004. Contributions to the palynology and phylogeny of Dioscorea (Dioscoreaceae). PhD thesis KU Leuven.

{{Refend}}

{{Taxonbar|from=Q71549}}

{{DEFAULTSORT:Dioscorea}}

Category:Dioscoreales genera

Category:Tubers

Category:Dioecious plants