View source for Biology:Taxonomy of wheat

{{Short description|Classification of wheat}}
[[Image:Blemiracle.jpg|thumbnail|right|250px|Miracle wheat (''Triticum turgidum'' var. ''mirabile'')]]
During 10,000 years of cultivation, numerous forms of [[Biology:Wheat|wheat]], many of them [[Biology:Hybrid|hybrids]], have developed under a combination of artificial and [[Biology:Natural selection|natural selection]].<ref>{{Cite journal |last=Shewry |first=P. R. |date=2009-04-01 |title=Wheat |journal=Journal of Experimental Botany |volume=60 |issue=6 |pages=1537–1553 |doi=10.1093/jxb/erp058 |pmid=19386614 |issn=0022-0957 |doi-access=free}}</ref><ref>{{Citation |last1=Fuller |first1=Dorian Q. |last2=Lucas |first2=Leilani |title=Wheats: Origins and Development |date=2014 |encyclopedia=Encyclopedia of Global Archaeology |pages=7812–7817 |publisher=Springer New York |doi=10.1007/978-1-4419-0465-2_2192 |isbn=9781441904263 |s2cid=129138746 }}</ref> This diversity has led to much confusion in the naming of wheats. Genetic and morphological characteristics of wheat influence its classification; many common and botanical names of wheat are in current use.

== ''Aegilops'' and ''Triticum'' ==

=== Similarities and differences ===
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[[File:Aegilops tauschii ARS-1.jpg|thumb|upright=0.5|Spike and spikelets of ''[[Biology:Aegilops tauschii|Aegilops tauschii]]'']]
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The genus ''[[Biology:Triticum|Triticum]]'' includes the wild and domesticated species usually thought of as wheat.

In the 1950s growing awareness of the genetic similarity of the wild goatgrasses (''[[Biology:Aegilops|Aegilops]]'') led botanists such as Bowden to amalgamate ''Aegilops'' and ''Triticum'' as one genus, ''Triticum''.<ref>{{Cite journal |last=Bowden |first=Wray M. |title=The Taxonomy and Nomenclature of the Wheats, Barleys, and Ryes and Their Wild Relatives |date=July 1959 |journal=Canadian Journal of Botany |volume=37 |issue=4 |pages=657–684 |doi=10.1139/b59-053 |issn=0008-4026}}</ref> This approach is still followed by some (mainly geneticists), but has not been widely adopted by taxonomists.<ref name=":0">{{Cite journal |last=Morrison |first=Laura A. |date=2001 |title=The Percival Herbarium and wheat taxonomy: yesterday, today, and tomorrow |url=https://ca1-tls.edcdn.com/Special-Issue-3-Wheat-Taxonomy-the-legacy-of-John-Percival.pdf |journal=The Linnean |publisher=The Linnean Society of London |volume=3 |pages=65–80}}</ref> ''Aegilops'' is morphologically highly distinct from ''Triticum'', with rounded rather than keeled [[Biology:Glume|glume]]s.<ref>{{Cite book |title=Wild wheats : a monograph of ''Aegilops'' L. and ''Amblyopyrum'' (Jaub. & Spach) Eig (Poaceae) : a revision of all taxa closely related to wheat, excluding wild ''Triticum'' species, with notes on other genera in the tribe Triticeae, especially ''Triticum'' |last=van Slageren |first=M. W. S. J. M. |date=1994 |publisher=Wageningen Agricultural University |others=ICARDA (International Center for Agricultural Research in the Dry Areas) |isbn=978-9067543774 |location=Wageningen, The Netherlands |oclc=32298786}}</ref>

=== Hybridisation and polyploidy ===

[[File:Polyploid wheat origins.svg|thumb|upright=2.5|Wheat origins by repeated hybridization and polyploidy (e.g. "6N" means 6 sets of chromosomes per cell rather than the usual 2). Only a few of the wheat species involved are shown. The goatgrass species involved are not known for certain.<ref name="Golovnina Glushkov Blinov Mayorov 2007">{{cite journal |last=Golovnina |first=K. A. |last2=Glushkov |first2=S. A. |last3=Blinov |first3=A. G. |last4=Mayorov |first4=V. I. |last5=Adkison |first5=L. R. |last6=Goncharov |first6=N. P. |title=Molecular phylogeny of the genus Triticum L |journal=Plant Systematics and Evolution |publisher=Springer |volume=264 |issue=3-4 |date=2007-02-12 |issn=0378-2697 |doi=10.1007/s00606-006-0478-x |pages=195–216}}</ref>]]

''Aegilops'' is important in wheat [[Biology:Evolution|evolution]] because of its role in two important hybridisation events. Wild [[Biology:Emmer|emmer]] (''T. dicoccoides'' and ''[[Biology:Triticum araraticum|T. araraticum]]'') resulted from the hybridisation of a wild wheat, ''[[Biology:Triticum urartu|T. urartu]]'', and an as yet unidentified goatgrass, probably closely related to ''[[Biology:Aegilops speltoides|Ae. speltoides]]''.<ref>{{Cite journal |last1=Gornicki |first1=Piotr |last2=Zhu |first2=Huilan |last3=Wang |first3=Junwei |last4=Challa |first4=Ghana S. |last5=Zhang |first5=Zhengzhi |last6=Gill |first6=Bikram S. |last7=Li |first7=Wanlong |date=2014-07-24 |title=The chloroplast view of the evolution of polyploid wheat |journal=New Phytologist |publisher=New Phytologist Foundation |volume=204 |issue=3 |pages=704–714 |doi=10.1111/nph.12931 |pmid=25059383 |issn=0028-646X |doi-access=}}</ref> Hexaploid wheats (e.g. ''[[Biology:Triticum aestivum|T. aestivum]]'' {{endash}} the most common {{endash}} and ''[[Biology:Triticum spelta|T. spelta]]'') are the result of a hybridisation between a domesticated tetraploid wheat, probably ''[[Biology:Triticum dicoccum|T. dicoccum]]'' or ''[[Biology:Triticum durum|T. durum]]'', and another goatgrass, ''[[Biology:Aegilops tauschii|Ae. tauschii]]'' or ''Ae. squarrosa''.<ref name="Golovnina Glushkov Blinov Mayorov 2007"/><ref name=":1">{{Cite journal |last1=Dvorak |first1=Jan |last2=Deal |first2=Karin R. |last3=Luo |first3=Ming-Cheng |last4=You |first4=Frank M. |last5=von Borstel |first5=Keith |last6=Dehghani |first6=Hamid |date=2012-05-01 |title=The Origin of Spelt and Free-Threshing Hexaploid Wheat |journal=Journal of Heredity |volume=103 |issue=3 |pages=426–441 |doi=10.1093/jhered/esr152 |pmid=22378960 |issn=0022-1503 |doi-access=free}}</ref> The hexaploid genome is an allohexaploid composed of two copies each of three subgenomes, AABBDD.<ref name = "Genetic-Control" /> The {{ Visible anchor|A genome}} is from ''T. urartu'' (AA).<ref name = "Genetic-Control" /> The {{ Visible anchor|B genome}} is a descendant of the {{ Visible anchor|S genome}} of an unidentified species related to ''Aegilops'' section ''Sitopsis'' (SS).<ref name = "Genetic-Control" /> This natural hybridization event happened ~3–0.8 MYA, yielding the tetraploid ''T. dicoccoides''.<ref name = "Genetic-Control" /> In time this tetraploid gave rise to ''[[Biology:Triticum turgidum|T. turgidum]]'', which gave rise to modern durum.<ref name = "Genetic-Control" /> Then ~0.4 MYA ''T. diccocoides'' naturally crossed with ''Aegilops tauschii'' (DD), adding the {{ Visible anchor|D genome}} and yielding the hexaploid.<ref name = "Genetic-Control" />

==Early taxonomy==
Botanists of the classical period, such as Columella, and in sixteenth and seventeenth century [[Biology:Herbal|herbal]]s, divided wheats into two groups, ''Triticum'' corresponding to free-threshing wheats, and ''Zea'' corresponding to hulled ('spelt') wheats.<ref name=":0" />

[[Biography:Carl Linnaeus|Carl Linnaeus]] recognised five species, all domesticated:<ref name=":0" />

* ''[[Biology:Triticum aestivum|T. aestivum]]'' Bearded spring wheat
* ''T. hybernum'' Beardless winter wheat
* ''[[Biology:Triticum turgidum|T. turgidum]]'' Rivet wheat
* ''[[Biology:Triticum spelta|T. spelta]]'' Spelt wheat
* ''[[Biology:Triticum monococcum|T. monococcum]]'' Einkorn wheat

Later classifications added to the number of species described, but continued to give species status to relatively minor variants, such as [[Biology:Winter wheat|winter-]] vs. spring- forms. The wild wheats were not described until the mid-19th century because of the poor state of botanical exploration in the [[Place:Near East|Near East]], where they grow.<ref name=":0" />

The development of a modern classification depended on the discovery, in the 1920s, that wheat was divided into 3 [[Biology:Ploidy|ploidy]] levels.<ref>{{Cite book|title=The Wheat Plant: A Monograph|last=Percival|first=John|date=1921|publisher=Duckworth & Co.|isbn=978-0715607909|location=[[Place:London|London]]|oclc=643506703|url=https://catalog.hathitrust.org/Record/001505622}}</ref>

==Important characters in wheat==
===Ploidy level===

As with many grasses, [[Biology:Polyploidy|polyploidy]] is common in wheat.<ref>{{Cite journal |last1=Levy |first1=Avraham A. |last2=Feldman |first2=Moshe |date=2002-12-01 |title=The Impact of Polyploidy on Grass Genome Evolution |journal=Plant Physiology |volume=130 |issue=4 |pages=1587–1593 |doi=10.1104/pp.015727 |issn=0032-0889 |pmc=1540263 |pmid=12481041}}</ref> There are two wild diploid (non-polyploid) wheats, ''[[Biology:Triticum boeoticum|T. boeoticum]]'' and ''[[Biology:Triticum urartu|T. urartu]]''. ''T. boeoticum'' is the wild ancestor of domesticated einkorn, ''[[Biology:Triticum monococcum|T. monococcum]]''.<ref>{{Cite journal |last1=Heun |first1=Manfred |last2=Schäfer-Pregl |first2=Ralf |last3=Klawan |first3=Dieter |last4=Castagna |first4=Renato |last5=Accerbi |first5=Monica |last6=Borghi |first6=Basilio |last7=Salamini |first7=Francesco |date=1997 |title=Site of Einkorn Wheat Domestication Identified by DNA Fingerprinting |jstor=2894198 |journal=Science |volume=278 |issue=5341 |pages=1312–1314 |doi=10.1126/science.278.5341.1312 |bibcode=1997Sci...278.1312H}}</ref> Cells of the diploid wheats each contain 2 complements of 7 chromosomes, one from the mother and one from the father (2n=2x=14, where 2n is the number of chromosomes in each somatic cell, and x is the basic chromosome number).

The polyploid wheats are tetraploid (4 sets of chromosomes, 2n=4x=28), or hexaploid (6 sets of chromosomes, 2n=6x=42). The tetraploid wild wheats are wild emmer, ''T. dicoccoides'', and ''[[Biology:Triticum araraticum|T. araraticum]]''. Wild emmer is the ancestor of all the domesticated tetraploid wheats, with one exception: ''T. araraticum'' is the wild ancestor of ''[[Biology:Triticum timopheevii|T. timopheevii]]''.<ref>{{Cite web |url=http://www.fao.org/docrep/006/y4011e/y4011e07.htm |title=Cytogenetics, phylogeny and evolution of cultivated wheats - B.S. Gill, B. Friebe |website=UN FAO (United Nations Food & Agriculture Organization) |access-date=2018-08-07}}</ref>

There are no wild hexaploid wheats, although feral forms of common wheat are sometimes found. Hexaploid wheats developed under domestication. Genetic analysis has shown that the original hexaploid wheats were the result of a cross between a tetraploid domesticated wheat, such as ''T. dicoccum'' or ''T. durum'', and a wild goatgrass, such as ''Ae. tauschii''.<ref name=":1" />

Polyploidy is important to wheat classification for three reasons:

*Wheats within one ploidy level will be more closely related to each other.
*Ploidy level influences some plant characteristics. For example, higher levels of ploidy tend to be linked to larger cell size.
*Polyploidy brings new genomes into a species. For example, ''Aegilops tauschii'' brought the D genome into hexaploid wheats, with enhanced cold-hardiness<ref>{{Cite journal |last1=Limin |first1=A.E. |last2=Fowler |first2=D.B. |date=October 1991 |title=Breeding for cold hardiness in winter wheat: problems, progress and alien gene expression |journal=Field Crops Research |volume=27 |issue=3 |pages=201–218 |doi=10.1016/0378-4290(91)90062-z |issn=0378-4290}}</ref> and some distinctive morphological features.<ref>{{Cite journal |last=Hillman |first=Gordon C. |date=2001 |title=Archaeology, Percival, and the problems of identifying wheat remains |url=https://ca1-tls.edcdn.com/Special-Issue-3-Wheat-Taxonomy-the-legacy-of-John-Percival.pdf |journal=The Linnean |publisher=The Linnean Society of London |volume=3 |pages=27–36}}</ref>

===Genome===
Observation of chromosome behaviour during [[Biology:Meiosis|meiosis]], and the results of hybridisation experiments, have shown that wheat genomes (complete complements of genetic matter) can be grouped into distinctive types. Each type has been given a name, A, B, and D. Grasses sharing the same genome will be more-or-less interfertile, and might be treated by botanists as one species. Identification of genome types is obviously a valuable tool in investigating hybridisation. For example, if two diploid plants hybridise to form a new polyploid form (an allopolyploid), the two original genomes will be present in the new form. Many thousands of years after the original hybridisation event, identification of the component genomes will allow identification of the original parent species.<ref>{{Cite journal |last1=Feldman |first1=M. |last2=Levy |first2=A.A. |date=2005 |title=Allopolyploidy – a shaping force in the evolution of wheat genomes |journal=Cytogenetic and Genome Research |volume=109 |issue=1–3 |pages=250–258 |doi=10.1159/000082407 |pmid=15753584 |s2cid=3593903 |issn=1424-8581}}</ref>

In ''Triticum'', five genomes, all originally found in diploid species, have been identified:

* A<sup>m</sup>, also called A<sup>b</sup> – present in wild einkorn (''T. boeoticum'').
* A – present in ''T. urartu''<ref name = "Genetic-Control" /> (closely related to ''T. boeoticum'' but not interfertile).
* B – present in most tetraploid wheats. Source not identified, but similar to ''Ae. speltoides''.<ref name = "Genetic-Control" />
* G – present in ''timopheevii'' group of wheats. Source not identified, but similar to ''Ae. speltoides''.
* D – present in ''Ae. tauschii'', and thus in all hexaploid wheats.<ref name = "Genetic-Control" >{{cite journal |last1=Laugerotte |first1=Julie |last2=Baumann |first2=Ute |last3=Sourdille |first3=Pierre |title=Genetic control of compatibility in crosses between wheat and its wild or cultivated relatives |journal=Plant Biotechnology Journal |publisher=Wiley |volume=20 |issue=5 |date=2022-02-24 |issn=1467-7644 |doi=10.1111/pbi.13784 |pages=812–832 |pmid=35114064 |pmc=9055826 }}</ref>

The genetic approach to wheat taxonomy (see below) takes the genome composition as defining each species.<ref name=USU>{{cite web |title=Genomes in ''Aegilops'', ''Triticum'', and ''Amblyopyrum'' |url=http://herbarium.usu.edu/Triticeae/genomesaegilops.htm |publisher=Utah State University Intermountain Herbarium |accessdate=16 June 2017 |url-status=dead |archive-url=https://web.archive.org/web/20060905134226/http://herbarium.usu.edu/Triticeae/genomesaegilops.htm |archive-date=September 5, 2006 |df=mdy-all}}</ref> As there are five known combinations in ''Triticum'' this translates into five ''super'' species:

* A<sup>m</sup> ''T. monococcum''
* A<sup>u</sup> ''T. urartu''
* BA<sup>u</sup> ''T. turgidum''
* GA<sup>m</sup> ''T. timopheevii''
* BA<sup>u</sup>D, ''T. aestivum''

For a larger list of genome names, see {{section link|Triticeae|Genetics}}.

===Domestication===
There are four wild species, all growing in rocky habitats in the fertile crescent of the [[Place:Near East|Near East]].<ref>{{Cite journal|last1=Harlan|first1=Jack R.|last2=Zohary|first2=Daniel|date=1966-09-02|title=Distribution of Wild Wheats and Barley|journal=Science|language=en|volume=153|issue=3740|pages=1074–1080|doi=10.1126/science.153.3740.1074|issn=0036-8075|pmid=17737582|bibcode=1966Sci...153.1074H|s2cid=25009927}}</ref> All the other species are domesticated. Although relatively few genes control domestication, and wild and domesticated forms are interfertile, wild and domesticated wheats occupy entirely separate habitats. Traditional classification gives more weight to domesticated status.

=== Hulled ''vs.'' free-threshing ===


All wild wheats are hulled: they have tough glumes (husks) that tightly enclose the grains. Each ''package'' of glumes, lemma and palaea, and grains is known as a spikelet. At maturity the rachis (central stalk of the cereal ear) disarticulates, allowing the spikelets to disperse.<ref>{{Cite book |title=Hulled wheats : proceedings of the First International Workshop on Hulled Wheats, 21-22 July 1995, Castelvecchio Pascoli, Tuscany, Italy |date=1996 |publisher=IPGRI |others=Padulosi, S. (Stefano), Hammer, K. (Karl), Heller, J. (Joachim), International Plant Genetic Resources Institute |isbn=978-9290432883 |location=Rome |oclc=36382216}}</ref>

The first domesticated wheats, einkorn and emmer, were hulled like their wild ancestors, but with rachises that (while not entirely tough) did not disarticulate at maturity. During the [[History:Pre-Pottery Neolithic B|Pre-Pottery Neolithic B]] period, at about 8000 BC, free-threshing forms of wheat evolved, with light glumes and fully tough rachis.

Hulled or free-threshing status is important in traditional classification because the different forms are usually grown separately, and have very different post-harvesting processing. Hulled wheats need substantial extra pounding or milling to remove the tough glumes.

===Morphology===
In addition to hulled/free-threshing status, other morphological criteria, e.g. spike laxness or glume wingedness, are important in defining wheat forms. Some of these are covered in the individual species accounts linked from this page, but Floras must be consulted for full descriptions and identification keys.

==Traditional ''vs.'' genetic classifications==
Although the range of recognised types of wheat has been reasonably stable since the 1930s, there are now sharply differing views as to whether these should be recognised at species level (traditional approach) or at subspecific level (genetic approach). The first advocate of the genetic approach was Bowden, in a 1959 classification (now historic rather than current).<ref>Bowden, W. M. 1959. "The taxonomy and nomenclature of the wheats, barleys, and ryes and their wild relatives". Canadian Journal of Botany 37:657–684.</ref> He, and subsequent proponents (usually geneticists), argued that forms that were interfertile should be treated as one species (the biological species concept). Thus emmer and hard wheat should both be treated as subspecies (or at other infraspecific ranks) of a single tetraploid species defined by the genome BA<sup>u</sup>. Van Slageren's 1994 classification  is probably the most widely used genetic-based classification at present.<ref>{{cite web|title=Wheat Taxonomy|url=https://www.k-state.edu/wgrc/wheat_tax/index.html|publisher=Kansas State University Wheat Genetics Resource Center|accessdate=14 October 2022}}</ref>

Users of traditional classifications give more weight to the separate habitats of the traditional species, which means that species that could hybridise do not, and to morphological characters. There are also pragmatic arguments for this type of classification: it means that most species can be described in Latin binomials, e.g. ''[[Biology:Triticum aestivum|Triticum aestivum]]'', rather than the trinomials necessary in the genetic system, e.g. ''T. a.'' subsp. ''aestivum''. Both approaches are widely used.

==Infraspecific classification==
In the nineteenth century, elaborate schemes of classification were developed in which wheat ears were classified to botanical variety on the basis of morphological criteria such as glume hairiness and colour or grain colour. These variety names are now largely abandoned, but are still sometimes used for distinctive types of wheat such as miracle wheat, a form of ''[[Biology:Triticum turgidum|T. turgidum]]'' with branched ears, known as ''T. t.'' L. var. ''mirabile'' Körn.

The term "[[Biology:Cultivar|cultivar]]" (abbreviated as ''cv.'') is often confused with "[[Biology:Species|species]]" or "domesticate". In fact, it has a precise meaning in botany: it is the term for a distinct population of a crop, usually commercial and resulting from deliberate plant-breeding. Cultivar names are always capitalised, often placed between apostrophes, and not italicised. An example of a cultivar name is ''T. aestivum'' cv. 'Pioneer 2163'. A cultivar is often referred to by farmers as a variety, but this is best avoided in print, because of the risk of confusion with botanical varieties. The term "[[Biology:Landrace|landrace]]" is applied to informal, farmer-maintained populations of crop plants.

==Naming==
Botanical names for wheat are generally expected to follow an existing classification, such as those listed as ''current'' by the {{ Visible anchor | Wheat Genetics Resource Center }}.<ref name="WGRC">{{ cite web | date= | website=[[Organization:Kansas State University|Kansas State University]] | archive-url=https://web.archive.org/web/20220517210329/https://www.k-state.edu/wgrc/wheat_tax/index.html | url=https://www.k-state.edu/wgrc/wheat_tax/index.html | title=Wheat Taxonomy | archive-date=May 17, 2022 }}</ref> The classifications given in the following table are among those suitable for use. If a genetic classification is favoured, the GRIN classification is comprehensive, based on van Slageren's work but with some extra taxa recognised. If the traditional classification is favoured, Dorofeev's work is a comprehensive scheme that meshes well with other less complete treatments. Wikipedia's wheat pages generally follow a version of the Dorofeev scheme – see the [[Biology:Wheat|taxobox]] on the Wheat page.

A general rule is that '''different taxonomic schemes should not be mixed in one context'''. In a given article, book or web page, only one scheme should be used at a time. Otherwise, it will be unclear to others how the botanical name is being used.

== Table of wheat species ==

{| border="1" cellpadding="2" cellspacing="0"
| || || colspan="2" align="center" style="background:#ccffcc; " | '''Wheat taxonomy – two schemes'''
|-
| '''Common name''' || Genome(s) || '''Genetic''' (<ref name="GRIN">[https://npgsweb.ars-grin.gov/ GRIN-Global Taxonomy]</ref>) || '''Traditional''' (Dorofeev ''et al.'' 1979<ref name="KSU-tax">{{cite web | url=http://www.ksu.edu/wgrc/Taxonomy/taxdor.html | archive-url=https://web.archive.org/web/20000522003809/http://www.ksu.edu/wgrc/Taxonomy/taxdor.html | archive-date=May 22, 2000 | title=Triticum classification according to Dorofeev & Migushova 1979 }}</ref>)
|-
| colspan="4" style="background:#ccffcc; " | '''Diploid (2x), wild, hulled'''
|-
| Wild einkorn || A<sup>m</sup> || ''Triticum monococcum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''aegilopoides'' <small>([[Biography:Johann Heinrich Friedrich Link|Link]]) Thell.</small> || ''[[Biology:Triticum boeoticum|Triticum boeoticum]]'' <small>Boiss.</small>
|-
| || A<sup>u</sup> || ''[[Biology:Triticum urartu|Triticum urartu]]'' <small>Tumanian ex Gandilyan</small> || ''Triticum urartu'' <small>Tumanian ex Gandilyan</small>
|-
| colspan="4" style="background:#ccffcc; " | '''Diploid (2x), domesticated, hulled'''
|-
| Einkorn || A<sup>m</sup> || ''Triticum monococcum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''monococcum'' || ''[[Biology:Triticum monococcum|Triticum monococcum]]'' <small>[[Biography:Carl Linnaeus|L.]]</small>
|-
| colspan="4" style="background:#ccffcc; " | '''Tetraploid (4x), wild, hulled'''
|-
| Wild emmer || BA<sup>u</sup> || ''Triticum turgidum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''dicoccoides'' <small>(Korn. ex Asch. & Graebn.) Thell.</small> || ''Triticum dicoccoides'' <small>(Körn. ex Asch. & Graebner) Schweinf.</small>
|-
| colspan="4" style="background:#ccffcc; " | '''Tetraploid (4x), domesticated, hulled'''
|-
| Emmer || BA<sup>u</sup> || ''Triticum turgidum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''dicoccum'' <small>([[Biography:Franz von Paula Schrank|Schrank]] ex Schübl.) Thell.</small> || ''[[Biology:Triticum dicoccum|Triticum dicoccum]]'' <small>[[Biography:Franz von Paula Schrank|Schrank]] ex Schübler</small>
|-
| || BA<sup>u</sup> || ''Triticum ispahanicum'' <small>Heslot</small> || ''Triticum ispahanicum'' <small>Heslot</small>
|-
| || BA<sup>u</sup> || ''Triticum turgidum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''paleocolchicum'' <small>Á. & D. Löve</small> || ''Triticum karamyschevii'' <small>Nevski</small>
|-
| colspan="4" style="background:#ccffcc; " | '''Tetraploid (4x), domesticated, free-threshing'''
|-
| Durum or macaroni wheat || BA<sup>u</sup> || ''Triticum turgidum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''durum'' <small>(Desf.) Husn.</small> || ''[[Biology:Triticum durum|Triticum durum]]'' <small>Desf.</small>
|-
| Rivet, cone or English wheat || BA<sup>u</sup> || ''Triticum turgidum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''turgidum'' || ''[[Biology:Triticum turgidum|Triticum turgidum]]'' <small>[[Biography:Carl Linnaeus|L.]]</small>
|-
| Polish wheat || BA<sup>u</sup> || ''Triticum turgidum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''polonicum'' <small>([[Biography:Carl Linnaeus|L.]]) Thell.</small> || ''[[Biology:Triticum polonicum|Triticum polonicum]]'' <small>[[Biography:Carl Linnaeus|L.]]</small>
|-
| Khorasan wheat || BA<sup>u</sup> || ''Triticum turgidum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''turanicum'' <small>(Jakubz.) Á. & D. Löve</small> || ''Triticum turanicum'' <small>Jakubz.</small>
|-
| Persian wheat || BA<sup>u</sup> || ''Triticum turgidum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''carthlicum'' <small>(Nevski) Á. & D. Löve</small> || ''[[Biology:Triticum carthlicum|Triticum carthlicum]]'' <small>Nevski in Kom.</small>
|-
| colspan="4" style="background:#ccffcc; " | '''Tetraploid (4x) – ''timopheevi'' group'''
|-
| colspan="4" style="background:#ccffcc; " | '''Wild, hulled'''
|-
| || GA<sup>m</sup> || ''Triticum timopheevii'' <small>(Zhuk.) Zhuk.</small> subsp. ''armeniacum'' <small>(Jakubz.) Slageren</small> || ''[[Biology:Triticum araraticum|Triticum araraticum]]'' <small>Jakubz.</small>
|-
| colspan="4" style="background:#ccffcc; " | '''Domesticated, hulled'''
|-
| || GA<sup>m</sup> || ''Triticum timopheevii'' <small>(Zhuk.) Zhuk.</small> subsp. ''timopheevii'' || ''[[Biology:Triticum timopheevii|Triticum timopheevii]]'' <small>(Zhuk.) Zhuk.</small>
|-
| colspan="4" style="background:#ccffcc; " | '''Hexaploid (6x), domesticated, hulled'''
|-
| Spelt wheat || BA<sup>u</sup>D || ''Triticum aestivum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''spelta'' <small>([[Biography:Carl Linnaeus|L.]]) Thell.</small> || ''[[Biology:Triticum spelta|Triticum spelta]]'' <small>[[Biography:Carl Linnaeus|L.]]</small>
|-
| || BA<sup>u</sup>D || ''Triticum aestivum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''macha'' <small>(Dekapr. & A. M. Menabde) Mackey</small> || ''Triticum macha'' <small>Dekapr. & Menabde</small>
|-
| || BA<sup>u</sup>D || ''Triticum vavilovii'' <small>Jakubz.</small> || ''Triticum vavilovii'' <small>(Tumanian) Jakubz.</small>
|-
| colspan="4" style="background:#ccffcc; " | '''Hexaploid (6x), domesticated, free-threshing'''
|-
| Common or bread wheat || BA<sup>u</sup>D || ''Triticum aestivum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''aestivum'' || ''Triticum aestivum'' <small>[[Biography:Carl Linnaeus|L.]]</small>
|-
| Club wheat || BA<sup>u</sup>D || ''Triticum aestivum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''compactum'' <small>(Host) Mackey</small> || ''[[Biology:Triticum compactum|Triticum compactum]]'' <small>Host</small>
|-
| Indian dwarf or shot wheat || BA<sup>u</sup>D || ''Triticum aestivum'' <small>[[Biography:Carl Linnaeus|L.]]</small> subsp. ''sphaerococcum'' <small>(Percival) Mackey</small> || ''Triticum sphaerococcum'' <small>Percival</small>
|-
|}

'''Note:''' Blank common name indicates that no common name is in use in the English language.

===Explanatory notes on selected names===
*''Triticum boeoticum'' <small>Boiss.</small> is sometimes divided into two subspecies:
**''T. boeoticum'' <small>Boiss.</small> subsp. ''thaoudar'' <small>(Reut. ex Hausskn.) E. Schiem.</small> – with two grains in each spikelet, distributed to east of fertile crescent.
**''T. boeoticum'' <small>Boiss.</small> subsp. ''boeoticum'' – one grain in each spikelet, in Balkans.
*''Triticum dicoccum'' <small>[[Biography:Franz von Paula Schrank|Schrank]] ex Schübler</small> is also known as ''Triticum dicoccon'' <small>[[Biography:Franz von Paula Schrank|Schrank]]</small>.
*''Triticum aethiopicum'' <small>Jakubz.</small> is a variant form of ''T. durum'' found in Ethiopia. It is not usually regarded as a separate species.
*''Triticum karamyschevii'' <small>Nevsky</small> was previously known as ''Triticum paleocolchicum'' <small>A. M. Menabde</small>.

== Artificial species and mutants ==

{{missing information|section|genome and ploidy, if possible|date=January 2022}}

Russian botanists have given botanical names to hybrids developed during genetic experiments. As these only occur in the laboratory environment, it is questionable whether botanical names (rather than lab. numbers) are justified. Botanical names have also been given to rare mutant forms. Examples include:

*''Triticum × borisovii'' Zhebrak – (''T. aestivum'' × ''[[Biology:Triticum timopheevii|T. timopheevi]]'')
*''Triticum × fungicidum'' Zhuk. – Hexaploid, artificial cross (''[[Biology:Triticum carthlicum|T. carthlicum]]'' × ''T. timopheevi'')
*''Triticum jakubzineri'' Udachin & Shakhm.
*''Triticum militinae'' Zhuk. & Migush. – mutant form of ''T. timopheevi''.
*''Triticum petropavlovskyi'' Udachin & Migush.
*''Triticum sinskajae'' Filat. & Kurkiev – mutant, free-threshing form of ''[[Biology:Einkorn wheat|T. monococcum]]''.
*''Triticum × timococcum'' Kostov
*''Triticum timonovum'' Heslot & Ferrary – Hexaploid, artificial cross.
*''[[Biology:Triticum zhukovskyi|Triticum zhukovskyi]]'' Menabde & Ericzjan (''T. timopheevi'' × ''T. monococcum''): 6N<ref name="Golovnina Glushkov Blinov Mayorov 2007"/>

==See also==
* [[Biology:Winter wheat|Winter wheat]] vs. spring wheat
* [[Biology:Cultivated plant taxonomy|Cultivated plant taxonomy]]
* List of Canadian Heritage Wheat Varieties

==References==
{{reflist}}

==Sources==
* {{cite book|editor-last1=Caligari | editor-first1 = P.D.S. | editor-first2 = P.E. | editor-last2 = Brandham |year=2001|url=https://ca1-tls.edcdn.com/Special-Issue-3-Wheat-Taxonomy-the-legacy-of-John-Percival.pdf|title=Wheat taxonomy: the legacy of John Percival|location=London|publisher=Linnean Society|edition=Linnean Special Issue 3|page=190}} 
* {{cite book | author=Percival, John | year=1921 | title=The wheat plant: a monograph | location=London | publisher=Duckworth}}
* {{cite book | author=Padulosi, Stefano, Karl Hammer and J. Heller | title=Hulled Wheats. Promoting the conservation and use of underutilized and neglected crops. 4. Proceedings of the First International Workshop on Hulled Wheats 21 July 1995 – 22 July 1995, Castelvecchio Pascoli, Tuscany, Italy | year=1996 | isbn=978-92-9043-288-3 | url=http://www.ipgri.cgiar.org/publications/pubfile.asp?ID_PUB=54 | url-status=dead | archive-url=https://web.archive.org/web/20060114193937/http://www.ipgri.cgiar.org/publications/pubfile.asp?ID_PUB=54 | archive-date=January 14, 2006 | df=mdy-all }}
* {{cite web | title=Wheat Classification Tables Site | url=https://www.ksu.edu/wgrc/Taxonomy/taxintro.html | archive-url=https://web.archive.org/web/20000310130245/http://www.ksu.edu/wgrc/Taxonomy/taxintro.html | url-status=dead | archive-date=March 10, 2000 | accessdate=January 15, 2006 }} Lists of ''Triticum'' names. An essential tool.
* {{cite web | title=GRIN taxonomy: ''Triticum''| url=http://www.ars-grin.gov/cgi-bin/npgs/html/genus.pl?12442 | accessdate=January 15, 2006}} Includes links to USDA germplasm collection, and public domain images [[Biology:Germplasm Resources Information Network|Germplasm Resources Information Network]] (GRIN)
* {{cite web | title=''Triticum'' taxonomy | work= Mansfeld's World Database of Agricultural and Horticultural Crops | url=http://mansfeld.ipk-gatersleben.de/pls/htmldb_pgrc/f?p=185:45:4280985933457155::NO::P7_BOTNAME,P7_DB_CHECKBOX1,P7_DB_CHECKBOX2,P7_DB_CHECKBOX3,P7_DB_CHECKBOX4:Triticum%2C%2C%2C%2C | accessdate=January 16, 2006}}

==External links==

===Taxonomy===
*[http://museum.agropolis.fr/pages/documents/bles_vilmorin/index.htm Les meilleurs blés (1880 and 1909)] Also on [http://uses.plantnet-project.org/fr/Vilmorin-Andrieux,_Les_meilleurs_bl%C3%A9s Pl@ntUse]. Beautifully illustrated French book on wheats then in cultivation and studied by the French breeders family Vilmorin.

===Genetics===
*[https://web.archive.org/web/20051227111443/http://herbarium.usu.edu/Triticeae/default.htm International Triticeae Consortium] Mainly concerned with the International Triticeae Meeting. Site includes genome tables for Triticeae.
*[http://wheat.pw.usda.gov/GG2/taxonomy.shtml GrainGenes: Triticeae Taxonomy]
*[http://wheat.pw.usda.gov/ggpages/awn/ Annual Wheat Newsletter]

===Morphology===
*[http://www.wheatbp.net/ Wheat: the big picture] Illustrated guide to life cycle of wheat plant

{{Wheat}}
{{Taxonomy of...}}

{{DEFAULTSORT:Wheat taxonomy}}
[[Category:Wheat|.]]
[[Category:Plant taxonomies|wheat]]

{{Sourceattribution|Taxonomy of wheat}}