Taxonomy of the Triticeae: a historical perspective*

Abstract

The history of the Triticeae is replete with changes in generic concepts, caused by taxonomists' struggle with the task of representing its highly reticulate history within the hierarchical classification system demanded by scientific nomenclature. Disagreement over the criteria used for delimiting taxa is an additional complication. Linnaeus' goal was an easy identification scheme. Subsequent taxonomists sought to improve Linnaeus' scheme by making his genera more 'natural', a vague term encompassing both general similarity and relatedness. In the 1880s Bentham and Hackel published nearly identical treatments of the tribe. These became the standard for the next fifty years. In 1933 Nevski advocated an explicitly evolutionary treatment, including much narrower generic concepts. Several of Nevski's generic concepts were adopted by European taxonomists, hut English speaking taxonomists continued to employ Bentham's. In the 1980s, Dewey and Love proposed that genera in the Triticeae should be determined primarily by genomic constitution.Although not all agree with treating such grpups as genera, it has been found productive to interpret data in terms of such groups. This will aid us in understanding the history of the Triticeae and evolutionary processes in general, a more important objective than complete nomenclatural agreement.

Phylogeny and differentiation of the St genome in Elymus L. sensu lato (Triticeae; Poaceae) based on one nuclear DNA and two chloroplast genes

“…Since Elymus L. was first described as a genus by Linnaeus [ 13 ], its circumscription and taxonomy has changed through times but is still uncertain because of the huge morphological variation within and between species, the polyploid origin of the genus and the frequent spontaneous hybridizations between species [ 12 , 14 – 16 ]. Löve [ 12 ] suggested that the taxonomic treatment for Triticeae species should be based on genomic constitution, recognizing StH to be the genomes of Elymus .…”

Mutualistic fungal endophytes in theTriticeae- survey and description

“…As highlighted, associating these fungi with species of Triticeae is not only obscured by incorrect identification of the host but also the complex taxonomy of the Triticeae tribe itself. Barkworth () states ‘There is little likelihood that there will ever be a single, universally accepted, taxonomic treatment of the Triticeae because of its highly reticulate evolutionary history and its low crossing barriers’. This complexity could also be interfering with our attempts to cluster endophyte strains with host species.…”

Toward a taxonomic definition of perennial wheat: a new species ×Tritipyrum aaseae described

“…There are many different ways to view living organisms in relation to one another, and each has some advantage and disadvantage. Morphological characterization, functional grouping, ability to interbreed and genomic constitution are all equally valid and correspondingly limited (Barkworth 1992;Spooner et al 2003). Genera within the Triticeae have been subjected to repeated reorganization based on new genomic information and there remain conflicting views as to their best classification (Feuillet and Muehlbauer 2009).…”

“…The historic fluidity of generic and morphological designation within the Triticeae makes this clarification especially important, and difficult. There have been significant reorganizations based on genomic data, and a unified concept of this tribe has not yet solidified (Dewey 1983;Löve 1984; Barkworth and Dewey 1985;Barkworth 1992;Wang 1992;Hsiao et al 1995;Li et al 2007;Barkworth et al 2009). This reorganization has an impact on nothogenera, hybrids of two or more established genera, which can lead to confusion, as in the case of 9Agrotriticum Cif.…”

“…The nothogenus 9Agrotriticum has been used inconsistently for the stable amphiploids of Triticum and Agropyron Gaertn. senso lato, and was formed when the genus Agropyron encompassed a wide range of now separate groups (Aase 1935;Barkworth 1992;Wang 2011). It was formally designated by Ciferri and Giacomini in (1950) where they also assigned names at the species level for unique combinations, but without typification (1950).…”