A revision ofTaraxacum sect.Piesis (Compositae)

Abstract

On the basis of allozyme and cultivation data, and of additional herbarium material, a taxonomic and nomenclatural revision ofTaraxacum sect.Piesis A.J. Richards exKirschner etStěpanek is provided. The section is made up of halophilous, sexually reproducing taxa. InT. stenocephalum Boiss. etKotschy,T. pindicum Kirschner etStěpanek, sp. nov., andT. perenne Kirschner etStěpanek, sp. nov., a tetraploid chromosome number has been recorded, representing the only known case of sexuality at the tetraploid level in the genus. The complex ofT. stenocephalum, includes some geographically and morphologically extreme populations treated as subspecies: subsp.gumusanicum (Soest)Kirschner etStěpanek, comb. nov., subsp.magnum Kirschner etStěpanek, subsp. nov., and subsp.daralagesicum (Schischk.)Kirschner etStěpanek, comb. nov. In addition toT. bessarabicum (Hornem.)Hand.-Mazz., a widely distributed Eurasian species,T. stenocephalum, a complex centred in Transcaucasia and Anatolia, andT. pachypodum H. Lindb., a North African endemic, four new species are described:T. salsum Kirschner etStěpanek, sp. nov., a diploid endemic confined to E Crimea,T. perenne Kirschner etStěpanek, sp. nov., a tetraploid sexual species known only from SW Crimea,T. pindicum Kirschner etStěpanek, sp. nov., a remarkable tetraploid endemic to the Pindos Mts., Greece, andT. salsitatis Kirschner, Stěpanek etYirdirimli, sp. nov., an Anatolian diploid species. Furthermore, a hybrid betweenT. salsum andT. bessarabicum from Crimea (documented on the basis of allozyme data elsewhere) is given a binomial,T. xmesohalobium Kirschner etStěpanek, nothosp. nov.