Palynomorphological study of Azerbaijanian Rubus species in comparison with the morphology of pollen of the whole genus

Abstract

Abstract We investigated pollen morphology of Rubus species from Azerbaijan. Pollen of 24 specimens from 15 species of all three Rubus subgenera has been studied using light, confocal laser scanning and scanning electron microscopes to estimate pollen characteristic variability and to describe pollen polymorphism and taxonomic value. Pollen grains are small or medium-sized, mainly three-colporate and spheroidal; composed apertures include meridional directed, long, narrow colpi and clear ori on the equator. Exine is thin, tectate and columellate, ornamentation is striate or striate-perforate with thin mainly long striae and perporations from zero to numerous between striae. Pollen of Azeri Rubus species are similar to European ones and it is difficult to distinguish from each other. Intraspecific and individual variability is manifested in size, shape, number and location of apertures, and patterns of ornamentation. The ordered structure of the individual variability of the characteristic shape (number and location of apertures) of pollen grains in the genus Rubus is described. An abundance of deviant forms was noted in the subgenus Rubus. An analysis of pollen morphology of investigated Rubus taxa around the world demonstrated that diagnostic feature into genus is ornamentation which can be divided into three groups: typical striate; non-typical striate and non-striate. The subgenus Rubus is uniform in exine pattern. Typical striate pollen is found throughout the world; however, variations of non-typical striate and non-striate pollen is revealed in Southeast Asia. Pollen data indicate a geographical center of species diversity in Southeast Asia.