A cryptic taxon rather than a hybrid species of Tragopogon (Asteraceae) from the Czech Republic

Tragopogon ×mirabilis Rouy is described as a diploid hybrid between T. porrifolius and T. pratensis. A population of T. ×mirabilis from Central Bohemia, Czech Republic, was recently investigated and, unlike previous reports of T. ×mirabilis, was found to be highly fertile. This fertile diploid hybrid population was considered to represent an alternative evolutionary pathway to polyploidy in Tragopogon. To determine the parentage of the plants from Bohemia, we investigated 12 samples of T. ×mirabilis with ITS, ETS, LFY and plastid (rpL16 gene, intron 1, tRNA-Leu (trnL) gene, intron, trnL-trnF intergenic spacer, psbA-trnH intergenic spacer, and trnG-trnT intergenic spacer) sequence data. None of the Bohemian plants have sequences that are consistent with a hybrid origin between T. porrifolius (incl. T. australis) and T. pratensis. Our data suggest that this fertile population of “T. ×mirabilis” may represent an unrecognised diploid species from the Angustissimi clade sensu Mavrodiev et al. (Int. J. Pl. Sci. 164: 1 – 19, 2005), a clade with a centre of distribution in the Caucasus, and hybrids of this unknown species with T. orientalis or T. hayekii (= T. orientalis L. var. hayekii Soó), a species closely related to T. pratensis and native to Bohemia. The Bohemian population of “Tragopogon ×mirabilis” clearly requires more investigation, but based on our data it does not appear to represent T. porrifolius × T. pratensis.