The paper reports a comparative study of the female gametophyte and especially synergid structure in sexual and apomictic dandelions. We analyzed diploid sexually reproducing Taraxacum linearisquameum (2n = 2x = 16) and two triploids, T. alatum and T. udum (2n = 3x =24), with autonomous embryo and endosperm development. There were no observed differences in the organization of the mature megagametophyte between the examined species. Both meiotically reduced and diplosporous embryo sacs showed typical polarity of the egg apparatus cells, together with development of a filiform apparatus in the synergids, but immunocytochemical analyses indicated that microtubules form longitudinal brush-like bundles adjacent to the filiform apparatus in the synergids of the sexual T. linearisquameum. This arrangement of cytoskeletal elements is similar to the configuration described in other amphimictic plants. The synergids of the apomictic T. alatum and T. udum show a uncharacteristic and relatively weak cytoskeleton with no brush-like bundles. We discuss the role of synergids in autonomous apomicts.
Chromosome numbers for 15 taxa of Hieracium L. s.str. from Bulgaria, Greece, Macedonia, Poland, Romania
and Slovakia are given and their metaphase plates are illustrated. Chromosome numbers are published for the
first time for H. vagneri Pax s.str. (2n = 4x = 36), H. wiesbaurianum subsp. herculanum Zahn (2n = 4x = 36),
H. wiesbaurianum subsp. kelainephes Nyár. & Zahn (2n = 3x = 27), as well as for two undescribed species
of hybrid origin between H. umbellatum L. and H. wiesbaurianum s.lat. (2n = 3x = 27), and between H. sparsum
Friv. and H. schmidtii s.lat. (2n = 3x = 27), and for three undescribed species of the H. djimilense agg.
(2n = 3x = 27), H. heldreichii agg. (2n = 3x = 27), and H. sparsum agg. (2n = 3x = 27). Furthermore, the chromosome
numbers of two undescribed species of hybrid origin between H. umbellatum L. and H. wiesbaurianum
s.lat. (2n = 3x = 27), and between H. sparsum Friv. and H. schmidtii s.lat. (2n = 3x = 27) are given. A new,
tetraploid chromosome number is given for H. barbatum Tausch from the northernmost locality of the species
in Europe.
Chromosome numbers for 15 taxa of Hieracium s.lat. (including two taxa of Pilosella Vaill.) from Bosnia and Herzegovina, Bulgaria, Greece, North Macedonia, Poland, Romania and Slovakia are given and their metaphase plates are illustrated. Chromosome numbers are published for the first time for H. pannosum subsp. parnassi Nägeli & Peter from Greece (3x and 4x), and for an undescribed species of H. sect. Cernua from North Macedonia (4x). A new, diploid chromosome number was found in H. bracteolatum s.lat. from Greece.
Chromosome numbers for 23 taxa of Hieracium L. from Bulgaria, Greece, Poland and Slovakia are given and their metaphase plates are illustrated. The ploidy level of 8 taxa was also confirmed by flow cytometry. Chromosome numbers are published for the first time for Hieracium bracteolatum subsp. koracis (Boiss.) Zahn (4x), H. marmoreum Pančić & Vis. (3x), H. ossaeum Zahn (3x), H. sartorianum Boiss. & Heldr. (3x), H. sericophyllum Nejčeff & Zahn (3x) as well as for five other undescribed species.
Somatic chromosome numbers are given for the following Taraxacum species: T. pieninicum, 2n=16; T. dentatum, 2n=24; T. fascinans, 2n=24; T. mendax, 2n=40; T. subalpinum, 2n=24; T. telmatophilum, 2n=24; T. cyanolepis, 2n=24; T. fulgidum, 2n=24; T. gentile, 2n=24; and T. undulatum, 2n=24. Chromosome numbers from Poland are published for the first time for T. dentatum, T. fascinans, T. mendax, T. subalpinum, T. telmatophilum, T. cyanolepis, T. fulgidum, T. gentile and T. undulatum.