Aegilops aucheri Boiss. — almost forgotten as a separate species — may also be regarded as rather close to a probable ancient donor of subgenome G for polyploid wheats of the timopheevii-zhukovskyi lineage

From the time of Theophrastus, for 2 millennia, many plants have been considered an herb liked by goats and called Aegilops. This had continued until the introduction of binary nomenclature by C.Linnaeus when he described the genus Aegilops L. This article contains excerpts from modern and historical classifications of the genus Aegilops as compiled by various authors through the years, but the emphasis is on Aegilops species from the section Sitopsis. Nowadays, there is some mixing between the Aegilops classifications proposed in the late 1920s. One of them was developed by P.M.Zhukovsky and had a section called Sitopsis, and another classification was developed by A.Eig, where this section was called Platystachyum but was divided into two subsections (Emarginata and Truncata), both of which are now within the generally accepted section Sitopsis. Numerous renamings of Aegilops species from the section Sitopsis during more than 2 centuries were noted. The interest in the section Sitopsis of the genus Aegilops is due to the fact that its species are potential donors of subgenomes of polyploid wheats. Polyploid wheats constitute two lineages with the genomic formulae BA, BAD, GA, GAA. The greatest doubts are raised by the first maternal subgenomes of these lines (B and G), the donor of which was some species of the section Sitopsis during the initial crossing with diploid wheat. A comparison of nucleotide sequences of complete chloroplast genomes of species from the Triticum–Aegilops alliance clearly indicates that species from the subsection Emarginata could not be this donor. The most likely donor of subgenomes B and G was either Ae. speltoides or a closely related species (from the subsection Truncata) that has not yet been found or is already extinct. Formerly, this section has included such species as Ae. aucheri, which is currently considered to be Ae. speltoides or its subspecies — merely its synonym — but which had probably been unreasonably rejected as an independent species by a substantial number of taxonomists in the second half of the 20th century. Sequencing of the complete plastid genome of this species from seven specimens of different geographical origin shows that it diverges from Ae. speltoides. The phylogenetic tree constructed on the basis of a comparison of genomes of diploid wheats, Aegilops from the subsection Emarginata, Ae. tauschii, Ae. aucheri, Ae. speltoides, and polyploid wheats of two lineages (turgidum-aestivum and timopheevii-zhukovskyi) indicates that Ae. aucheri can also be considered a potential donor of subgenome G for timopheevii-zhukovskyi wheats, whereas turgidum-aestivum wheats are distant from the other species.