A distinctive group of species allied to Taraxacum danubium (T. sect. Erythrosperma, Compositae-Crepidinae): a taxonomic revision

Within Taraxacum section Erythrosperma, several relatively distinct species groups are recognized. One of them, characterized by leaves with numerous, usually patent, very narrow lateral segments, frequently with their most distal part dilated, and outer phyllaries patent or arcuate-recurved, often with tips approaching the involucre base, with narrow whitish borders, includes species similar to the Central European Taraxacum danubium. This group comprises nine species, the majority of them (five species) being confined to the Balkan Peninsula. Another diversity centre of the group is the southernmost Ukraine. The most widespread species is T. persicum, extending from Iran and the lower river Volga to Central Europe. A detailed taxonomic revision of the whole group is presented, and descriptions, illustrations and lists of specimens studied are given. Two Balkanic species are newly described, the name T. danubium is lectotypified, another three names are relegated to the synonymy of the accepted names, and an unclear name, T. pineticola, is discussed. The species concept in Taraxacum is briefly expounded.