Pollen morphology of Polish native species of the Rosa genus (Rosaceae) and its relation to systematics

The morphology of pollen grains of 16 species from the Rosa L. genus were studied (i.e. R. agrestis, R. canina, R. dumalis, R. gallica, R. inodora, R. jundzillii, R. kostrakiewiczii, R. majalis, R. micrantha, R. mollis, R. pendulina, R. rubiginosa, R. sherardii, R. tomentosa, R. villosa, and R. zalana). The material came from 16 native localities of those species in Poland. The measurements are based on at least 30-50 randomly selected, fully developed pollen grains per specimen. In total, 500 pollen grains were examined. They were analysed for 13 quantitative features of pollen grains and exine sculpturing and the following qualitative traits: outline, shape, "operculum" structure. The diagnostic features of pollen grains of studied species were: length of polar and equatorial axes and length of ectocolpi. The above-mentioned pollen grain morphological features make isolation of one species possible: R. gallica. R. gallica is distinguished for its highest values of the length of polar and equatorial axes, and the length of ectocolpi. The obtained analytical results of operculum and exine sculpture features, considered as diagnostic, corroborated only slightly their priority significance for the isolation of the examined species and sections. The collected data failed to confirm fully the current taxonomical division of the Rosa genus into sections (only section Gallicanae from R. gallica is isolated) as well as consanguinity relationships between the examined species from the Caninae section. On the dendrogram, both species closely related with each other as well as those from other developmental lines were found in the same group. These equivocal results are by no means surprising because the Caninae section is the most polymorphic group in the Rosa genus, and contemporary Caninae are of the nature of a swarm of R. canina hybrids as a link combining all taxons of the section.