New data on pollen morphology of the genus Camphorosma (Chenopodiaceae)

Abstract

Recent molecular phylogenetic studies of Camphorosmoideae (Chenopodiaceae) demonstrated that Camphorosma is monophyletic. Palynomorphological peculiarities are used in taxonomy as additional diagnostic features and pollen analysis. Pollen morphology was studied using light and scanning electron microscopy, based on 13 specimens belonging to four species (C. annua, C. lessingii, C. monspeliaca and C. songorica). The aim of this research was to provide new data on pollen characteristics of the above mentioned species and to evaluate their taxonomic value. The results obtained show that pollen grains are pantoporate, spheroidal, circular in outline, undulate or slightly undulate on the edges; small or medium-sized. Pores are circular, with distinct margins. Exine sculpture is nanoechinate, tectum psilate or psilate-perforate. Pore membranes are nanoechinate. Taxonomic relevance of the most important characters of pollen grains (pollen diameter, pore number, pore diameter, distance between pores and between pore centres, C/D value, nanoechini density, presence/absence of perforations, number of nanoechini on pore membranes, structure of columellae) is discussed. The exine structure of pollen grains of all species was analysed for the first time in the current study. Pollen morphology proved to be an important additional source of information for taxonomy for species-specific identification and pollen analysis within Camphorosma. Palynomorphological data are interpreted in the existing phylogenetic framework.