Concepts and nomenclature of the Farro wheats, with special reference to Emmer, Triticum turgidum subsp. dicoccum (Poaceae)

Abstract

This paper discusses the different taxonomic concepts of the wheat group as exemplified by three species, commonly known together as ‘Farro’: diploid Einkorn, tetraploid Emmer and hexaploid Spelt. A narrow, morphology-based concept is contrasted with a much wider, genome-based one, leading to profound differences in the recognition of taxa at species level and below. The latter concept accepts far fewer taxa; it is advocated here and its effect illustrated for the Farro wheats. Considerations regarding the nomenclature of the accepted taxa are presented, applying both the International Code for the Nomenclature of Cultivated Plants (ICNCP) and the International Code of Nomenclature for algae, fungi and plants (ICN or the ‘Melbourne Code’). Within the genus Triticum L. we propose Farro wheats to be classified at subspecies rank, and to be defined as the total of their cultivars united under a botanical name. Einkorn is T. monococcum L. (the cultivars in subsp. monococcum) and Spelt T. aestivum L. subsp. spelta (L.) Thell.; if one chooses the species level the names are T. monococcum L. and T. spelta L., respectively. We show that, based on consideration of the original literature, the ICN and relevant type specimens, the correct name and authorship of Emmer at subspecies level should be T. turgidum L. subsp. dicoccum (Schrank ex Schubl.) Thell. At species level we recommend using T. farrum Bayle-Bar., published in 1809, over the more widely known T. dicoccum Schrank ex Schubl. from 1818, and provide arguments for rejecting T. dicoccon Schrank 1789, T. album Gaertn. 1790, T. spelta sensu Host 1809 (non Linnaeus) and (possibly) T. atratum Host 1809.