Taxonomic significance of pollen morphology of African Oreobliton, and related genera Aphanisma, Beta, Hablitzia, and Patellifolia (Amaranthaceae)

Pollen morphology of 10 taxa belonging to the genera Oreobliton, Aphanisma, Beta, Hablitzia, and Patellifolia (subfamily Betoideae, Chenopodiaceae/Amaranthaceae sensu APG IV) was investigated using both light and scanning electron microscopy. The research aimed to provide data on their pollen characteristics and to evaluate their significance for taxonomy and phylogeny. All pollen grains are pantoporate, spheroidal in shape, usually circular in outline (rarely polygonal), small and medium-sized. Two types of exine sculpture were recognised: type I – nanoechinate, and type II – psilate. For the first time, a psilate type of exine sculpture was revealed in the pollen grains of a member of subfam. Betoideae (Beta macrocarpa). Three pollen types (I – Hablitzieae, II – Corollinae, and III – Beta/Macrocarpae) were found and described based on the pollen diameter, pore diameter, distance between pores and between pore centres, pore number, C/D value, exine thickness, nanoechini: height, width at the base, number/4 µm², and number on pore membranes. The diagnostic pollen characters that separate the tribes Hablitzieae and Beteae are: exine thickness and structure of columellae. UPGMA dendrogram, based on quantitative pollen traits, supports the differentiation of most taxa at genera and species level. UPGMA dendrogram, based on qualitative palynological data, supports the differentiation of sections Corollinae, Beta, and Macrocarpae. The pollen morphology of Aphanisma blitoides, Beta lomatogona, B. macrocarpa, B. macrorhiza, Oreobliton thesioides, and Patellifolia patellaris, was studied for the first time in the present investigation.