A new cytotype of Jacobaea vulgaris (Asteraceae): frequency, morphology and origin

Jacobaea vulgaris subsp. vulgaris (syn. Senecio jacobaea subsp. jacobaea) constitutes an intricate polyploid complex distributed in Europe. Four cytotypes have been reported in this species, three with euploid (diploid, tetraploid and octoploid; 2n020, 40 and 80) and one with aneuploid (2n 032) chromosome numbers. Here we report that the diploid chromosome number (2n020) reported from Bulgaria is due to misidentification with Jacobaea aquatica. On the other hand, we have discovered a new, hexaploid (2n 06x060) cytotype within J. vulgaris subsp. vulgaris using flow cytometry. The new cytotype occurs within four sympatric populations of otherwise tetraploid and octoploid plants in Pannonia (one locality in the eastern Czech Republic and two localities in southwestern Slovakia) and in Podillya (one locality in western Ukraine). The frequency of hexaploid individuals within 76 studied populations is very low (only 10 of 693 analysed plants), and hexaploids probably represent hybrids between tetraploid and octoploid plants. Three mixed populations with hexaploid plants were subjected to detailed morphological and pollen fertility analyses. Multivariate morphometric analysis reveals partial separation of tetraploid and octoploid plants, whereas hexaploid individuals are similar in morphology to octoploids. In comparison with tetraploids, octoploids and hexaploids exhibit slightly longer ray florets, involucral bracts and tubular florets and more hairy outer achenes. Hexaploid plants display larger pollen grains and lower pollen fertility compared to tetraploids and octoploids

Three new rose microspecies from sect. Rubiginosae in Slovakia

The article deals with the distribution of three species from the genus Rosa in Slovakia. Field research, sampling and herbarium sheet revision at the Herbarium of Department of Botany, Faculty of Natural Sciences Comenius University (SLO) and the Herbarium of Institute of Botany, Slovak Academy of Sciences (SAV) showed new data on the distribution of Rosa pocsii Kerényi-Nagy, Rosa polyacantha (Borbás) H. Br. and Rosa zagrabiensis Vuk. et H. Br. in Slovakia. Detailed taxonomic description, distribution of selected taxa in Slovakia, a determination key and a comparative table of the sect. Rubiginosae are given

Introgressive Hybridization of Senecio hercynicus and S. ovatus (Compositae, Senecioneae) along an altitudinal gradient in Harz National Park (Saxony-Anhalt, Germany)

Introgressive hybridization of Senecio hercynicus and S. ovatus (Compositae, Senecioneae) was studied in a hybrid zone on the southern slopes of Mt Brocken (Harz Mountains, Germany). A total of 415 plants representing 10 stands along an altitudinal gradient were investigated using multivariate statistical analyses of morphological characters and molecular markers (random amplified polymorphic DNA[RAPD]). Both types of traits detected pure S. hercynicus stands on the summit plateau, pure S. ovatus stands at the lowest elevations, and hybrid swarms at intermediate elevations. While morphological and molecular patterns coincided, some individuals in hybrid stands combined morphological patterns typical of S. ovatus with RAPD patterns typical of S. hercynicus, and vice versa. In general, introgression was symmetrical within stands, though one stand combined S. ovatus characters with the glandular hair typical for S. hercynicus, and two stands combined a S. hercynicus typical RAPD genotype with morphological characters shifted towards S. ovatus. Because pure stands of S. hercynicus occurred only on the summit plateau of Mt Brocken, and markers typical for S. ovatus were detectable in stands up to 1040 m a.s.l., future fusion or assimilation of the rare form, S. hercynicus, by the more widespread S. ovatus appears possible at Mt Brocken