Six populations of Hieracium echioides subsp. echioides var. tauscheri from the Danube Basin between Bratislava and Budapest (locations: Balinka, Čenkov, Devín, Dorog, Győr, Pilis) were analysed using allozyme and karyological analysis. Five allozyme systems (EST, LAP, 6PGDH, PGM, and SKDH) were used to analyse the genetic structure of the examined populations. Analyses revealed low genetic variation both within- and among populations. Four multilocus allozyme phenotypes were detected; three populations (Čenkov, Devín and Győr) possessed phenotype I exclusively, while phenotype II was found only in the Balinka and Dorog populations. Two different phenotypes were found in the population of Pilis (phenotypes III and IV). However, due to the complex banding patterns generated for EST, allelic interpretationwas not possible, and the Balinka and Dorog populations appeared to possess different phenotypes. All populations proved to be tetraploid (2n = 36) and agamospermous. The geographic distribution pattern of the analysed populations (one allozyme phenotype at several isolated localities) may reflect a more common occurrence of the taxon in the past. Landscape changes, caused by changes in human management of the country, may have resulted in a loss of suitable localities, mainly open sandy habitats. These changes may have caused the reduction and fragmentation of H. *tauscheri habitat.
A taxonomic concept for the Hieracium nigrescens agg. (H. alpinum ≥ H. murorum) in the Western Carpathians is proposed. Three taxa at the species level are recognized, i.e. Hieracium jarzabczynum, H. mlinicae and H. vapenicanum. One new combination, Hieracium mlinicae (Hruby et Zahn) Chrtek f. et Mráz (H. nigrescens subsp. mlinicae Hruby et Zahn) is published. All taxa should be considered as endemic to the Western Carpathians (both the Polish and Slovakian parts). Detailed descriptions, drawings, lists of localities, distribution maps and determination key are provided along with a comparison with the last comprehensive account of the group (by Zahn 1936). Several lectotypes were chosen for the taxa recognized by Zahn within H. nigrescens s.l.