Comparative pollen morphology studies on some species of Brassicaceae in Turkey

Pollen aperture type, shape, size, polar axis length, equatorial axis length, P/E ratio, colpus length, thickness of the sexine and nexine, S/N ratio, ornamentation type, and lumen shape and width were determined by using light and scanning electron microscope. A multivariate analysis was carried out using the Gover’s general similarity coefficient and UPGMA based on 3 qualitative and 8 quantitative pollen characters for 43 taxa belonging to 30 genera and 19 tribes. In all of the taxa studied, the pollen grains were generally small or medium-sized, tricolpate, except in Matthiola longipetala, with an inconspicuous aperture. The shape varied from prolate-spheroidal to perprolate. The exine ornamentation was microreticulate, reticulate, or macroreticulate. In some species, reticulate ornamentation was found together with microreticulate, and in some others, with macroreticulate ornamentation. It was seen that some taxa belonging to some genera placed near each other in the dendogram partially supported some tribes, such as Brassiceae, Alysseae, Sisymbrieae, and Camelineae. It is notable that some closely-related tribes were placed near each other on the dendrogram, which partially supports some previous molecular studies. In addition to exine ornamentation, the pollen size, shape, sexine and nexine thickness, and colpus length were the most useful characters. These characteristics can be used to identify and distinguish some genera, species and partly tribes within the family. They also provide detailed information on the pollen grains of some Brassicaceae taxa, some of which were studied herein for the first time, and this knowledge will be useful for comparisons in future pollen studies.