Wheat Synonymy Tables Project


The taxonomy of the wheats is controversial and without any consistency in the classifications followed by wheat researchers around the world. Each of the current classifications varies in either or both genus and species concepts. In the case of generic treatment, the wheats are sometimes treated in one large genus (Triticum sensu lato) or treated as two separate genera (Triticum and Aegilops). Other generic concepts also exist. The diploid T-genome species can either be treated as Ae. mutica or as Amblyopyrum muticum. The cytogenetic treatment of Löve (1984) divides the wheats into 16 genomically defined genera.


As the following examples will show, species treatment is complicated by the various taxonomic approaches for constructing wheat classifications as well as by nomenclatural mistakes. The species epithets can change according to generic concept--e.g., the diploid C-genome species is named T. dichasian when treated in Triticum and Ae. markgrafii when treated in Aegilops. Incorrect names still persist--e.g., researchers still mistakenly use the illegitimate name Ae. squarrosa for the diploid D-genome species. Many of the domesticated wheat taxa are treated as species in some classifications and as lower ranking taxa in others--e.g., durum wheat which is variously treated as T. durum, T. turgidum ssp. durum, and T. turgidum ssp. turgidum convar. durum. Some taxa are treated in some classifications and not in others -- e.g., T. ispahanicum.


These inconsistencies in taxonomic treatment affect all members of the wheat research community. Communication is difficult when everyone is speaking a different language. Genebank managers are often unclear on what germplasm is being requested when the researcher is following a taxonomic system different from that followed by the genebank. Misunderstanding of the taxonomic concept behind a species name can lead to mistakes in the selection of taxa to study. In the literature, researchers frequently fail to specify the classification they are following. There is also the problem of researchers who fail to follow any taxonomic treatment by arbitrarily choosing names without regard to classification. This situation presents a time-consuming, and often confusing, task for those who wish to decipher the exact identity of taxa reported in research articles.

Participants in the Taxonomy Workshop held at the 9th International Wheat Genetics Symposium (2-7 August 1998, Saskatoon, Canada) agreed that a practical first-step solution for these problems is the development of an interactive database of Synonymy Tables on GrainGenes. As envisioned, the system provides the tools by which researchers can consistently follow their preferred wheat classification and access all other names by which a wheat species is currently treated. While the Synonymy Tables database offers a preliminary remedy for the confusion caused by so many different competing classifications, workshop participants agreed that the ultimate solution requires a monographic revision of wheat taxonomy.


The GrainGenes Synonymy Tables Database Project design and goals are as follows:


1. The Synonymy Tables database will have three components that will enable users to associate names with synonyms and names with classifications:


(a) A table listing the species names with authorities (and where relevant, lower ranking taxa at subspecific and botanical varietal levels) will be constructed for each of the 12 principal classifications currently in use. For Triticum: van Slageren (1994), Kimber & Sears/Kimber & Feldman (1987), Flora of Turkey (1985), Löve (1984), Dorofeev & Migushova (1979), Mac Key (1975). For Aegilops and Amblyopyrum: van Slageren (1994), Flora of Turkey (1985), Witcombe (1983), Hammer (1980), Kihara (1954), Eig (1929). See below for citations to these classifications.


(b) Each taxon name in a classification table will link to its synonyms. For example, in the table for the van Slageren classification, the diploid D-genome species Ae. tauschii Coss. will link to its synonyms--Ae. squarrosa L., T. tauschii (Coss.) Schmal., T. aegilops P. Beauv. ex Roem. & Schult., Patropyrum tauschii (Coss.) Löve.


(c) Each synonym will link to its associated classification(s). Following the above example with Ae. tauschii, its four synonyms will link to their respective classifications--Ae. squarrosa L. [name in the Eig, Kihara, and Witcombe classifications], T. tauschii (Coss.) Schmal. [name in the Kimber & Sears/Kimber & Feldman classification], T. aegilops P. Beauv. ex Roem. & Schult. [correct name with priority in Triticum sensu lato], Patropyrum tauschii (Coss.) Löve [Löve, 1984].


Each name also will link to itself when treated with the same name in other classifications. For example, Ae. tauschii Coss. in the van Slageren classification table will link to Ae. tauschii Coss. in the tables for the Hammer and Flora of Turkey classifications.


2. Project coordinators include: Synonymy Table construction--Laura Morrison (Oregon State University) and John Raupp (Kansas State University); GrainGenes database implementation--Dave Matthews and Gerry Lazo (USDA-ARS); Triticeae taxonomy liaison--Mary Barkworth (Utah State University); wheat genetics liaisons--Giles Waines (University California-Riverside) and Jan Dvorak (University of California-Davis).


3. Notices of the progress and eventual availability of the Synonymy Tables database will appear in the Wheat Information Service (published January and June) and the Annual Wheat Newsletter (published June).


4. GrainTax, an internet mailgroup and bulletin board, has been set up as a discussion forum and an information exchange service for issues associated with wheat taxonomy. Notices published in the Wheat Information Service and the Annual Wheat Newsletter also will be posted here.


5. To join the GrainTax mailgroup, contact Dave Matthews, matthews@greengenes.cit.cornell.edu. The GrainTax bulletin board can be reached at http://wheat.pw.usda.gov:8000/cgi-bin/mboard/graintax/list.gci.


6. Recipients of this notice are encouraged to pass it on to their fellow wheat researchers.



References for the 12 taxonomic classifications in the Synonymy Tables database are as follows:


Davis, P.H. (ed.). 1985. Flora of Turkey and the East Aegean Islands. 9:232-255.


Dorofeev, V.F. and Migushova, E.F. 1979. Wheat. Vol. 1 (346 pp.) in V.F. Dorofeev and O.N. Korovina (eds.), Flora of Cultivated Plants. Leningrad [St. Petersburg]: Kolos. [in Russian].


Eig, A. Monographisch-kritische Übersicht der Gattung Aegilops. Feddes Repert. spec. nov. reg. veg. Beih. 55: 1-228.


Hammer, K. 1980. Vorarbeiten zur monograhischen Darstellung von Wildpflanzensortimenten: Aegilops L. Kulturpflanze 28:33-180 [in German].


Kihara, H. 1954. Considerations on the evolution and distribution of Aegilops species based on the analyser-method. Cytologia 19:336-319.


Kimber, G. and Feldman, M. 1987. Wild wheat: an introduction. Spec. Rpt. 353. Coll. Agri. Univ. Mo. Columbia.


Kimber, G. and Sears, E.R. 1987. Evolution in the genus Triticum and the origin of cultivated wheat. Pp. 154-164 in: Heyne, E.G. (ed.), Wheat and wheat improvement, ed. 2. Madison.


Löve, Á. 1984. Conspectus of the Triticeae. Feddes Repert. 95:425-521.


Mac Key, J. 1975. The boundaries and subdivision of the genus Triticum. Proc. 12th Int. Bot. Congr. Leningrad [St. Petersburg].

Slageren, M.W. van. 1994. Wild wheats: a monograph of Aegilops L. and Amblyopyrum (Jaub. & Spach) Eig. Wageningen Agric. Univ. Pap. 1994 (7).


Witcombe, J.R. 1983. A guide to the species of Aegilops L.: their taxonomy, morphology and distribution. IBPGR [IPGRI], Rome.