Chromosome numbers and reproductive systems in selected representatives of Hieracium subgen. Pilosella in the Krkonoše Mts (the Sudeten Mts)

Chromosome numbers and reproductive systems are given for the following taxa of Hieracium subgen. Pilosella occurring in the Krkonoše Mts: H. pilosella L. (2n = 36, sexual), H. lactucella Wallr. (2n = 18, sexual), H. caespitosum Dumort. (2n = 36, the mode of reproduction unknown), H. aurantiacum L. (2n = 36, apomictic), H. schultesii F.W. Schultz (2n = 36, sexual; 2n = 45, apomictic), H. macrostolonum G. Schneider (2n = 54, the mode of reproduction unknown), H. glomeratum Froel. (2n = 36, 45, both apomictic), H. floribundum Wimm. et Grab. (2n = 36, apomictic), H. iseranum Uechtr. (2n = 36, apomictic), H. apatelium Nägeli et Peter (2n = 36, both sexual and apomictic; 2n = 45, apomictic), H. piloselliflorum Nägeli et Peter (2n = 36 the mode of reproduction unknown; 2n = 45, 44, apomictic; 2n = 54, apomictic), H. stoloniflorum Waldst. et Kit. (2n = 54, apomictic), H. rubrum Peter (2n = 54, apomictic). Chromosome numbers are reported for the first time for H. apatelium, H. iseranum, and H. piloselliflorum, a new chromosome number was determined for H. macrostolonum and H. schultesii. The group of species (H. caespitosum, H. glomeratum, H. floribundum, H. iseranum) has been found to have a single long marker chromosome in the karyotype; this fact supports the view of their relationship. The mode of reproduction is here examined for the first time in polyploid hybridogenous species H. iseranum, H. apatelium, H. piloselliflorum, H. stoloniflorum, H. rubrum and H. schultesii from nature; the apomictic reproduction of tetraploid H. floribundum and of pentaploid H. glomeratum is also a new information. The variation of Hieracium subgen. Pilosella in the Krkonoše Mts is discussed in connection with the presence of at least four sexual types and diversity of reproductive systems. The occurrence of H. stoloniflorum in the Krkonoše Mts is dealt with.