Pollen morphology of representatives of the genus Petrosimonia (Chenopodiaceae s. str. / Amaranthaceae s. l.) of the flora of Ukraine

Pollen morphology of Petrosimonia brachiata, P. oppositifolia, and P. triandra (Salsoloideae, Chenopodiaceae s. str. / Amaranthaceae s. l.) of the flora of Ukraine was investigated using light and scanning electron microscopy. For Petrosimonia triandra, such data are provided here for the first time. The objective of the present study was to obtain data on pollen characteristics of these species and to assess the significance of characters for species-specific identification. Pollen grains in the studied species are pantoporate, spheroidal, circular in outline, slightly undulate or undulate on the edges; small- and medium-sized. Exine sculpture is nanoechinate, tectum is psilate-perforate. Pore membranes are nanoechinate. The exine structure (columellae) of pollen grains of all species was analyzed for the first time in the present study. Significance of pollen grain traits for the taxonomy and pollen analysis in paleopalynology is discussed. UPGMA dendrograms based on palynomorphological data support the differentiation of studied species. Pollen grains of P. triandra differ from those of P. brachiata and P. oppositifolia in their size, distances between pores and between pore centers, as well as the number of pores. Pollen grains in P. brachiata have larger size and number of pores, larger nanoechini, and shorter columellae than those in P. oppositifolia.