Chromosome number variation in the genus Rubus in the Czech Republic. III.

The paper provides information on chromosome numbers in 20 species of the genus Rubus, belonging mostly to subgenus Rubus (18 species). The plants studied were collected at 67 localities in the Czech Republic (Bohemia and Moravia). Three ploidy levels were recorded: diploid (3 species), tetraploid (16 species) and one triploid. The diploid species represent the subgenera Rubus, Idaeobatus and Cylactis. New chromosome number reports are given for the following five tetraploid species (2n = 28): R. wimmerianus (Sudre) Spribille, R. thelybatos Caflisch, R. acanthodes H. Hofmann, R. brdensis Holub and R. josefianus H. E. Weber; the triploid R. elatior Gremli (2n = 21) probably also belongs here. The karyology of R. bohemiicola Holub was studied for the first time. This species is characterized by a tetraploid level combined with a structural change of the karyotype; it is manifested by the chromosome number of 2n = 27 + fragment, involving one heteromorphic pair of chromosomes. This record of a conspicuous karyotype rearrangement, concerning species of this genus of native occurrence, is reported only sporadically in the literature. For the remaining 13 species, the chromosome numbers published hitherto were confirmed: R. illecebrosus Focke, R. xanthocarpus Bureau et Franchet, R. sulcatus Vest, R. plicatus Weihe et Nees, R. senticosus Weihe, R. ulmifolius Schott, R. nemoralis P. J. Mueller, R. laciniatus Willd., R. macrophyllus Weihe et Nees, R. sprengelii Weihe, R. gliviciensis (Sudre) Spribille, R. hirtus Waldst. et Kit. and R. gothicus E. H. L. Krause. For all species studied, data on their overall distribution and on their occurrence in the Czech Republic are given. Notes on taxonomy are added to R. elatior; new data on chorology are given for R. elatior, R. nemoralis, R. thelybatos, R. brdensis and R. josefianus.