Pollen morphology of Doronicum L. (Asteraceae: Senecioneae) from Turkey and its taxonomical implications

Abstract

Abstract The main purpose of this study is the palynological characterization of Doronicum L. taxa that occur naturally in Turkey. In this context, the pollen morphology of 11 species and one subspecies of Doronicum was researched in detail by light microscopy and scanning electron microscopy (SEM). Furthermore, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were carried out to identify closely related species and palynological characters that could potentially be used to distinguish the studied taxa. Pollen grains were found to be isopolar monad and tricolporate. Pollen were prolate-spheroidal in shape, with a circular amb. SEM showed the exine ornamentation was echinate-perforate. Differences in the bases and ends of the spines were observed; therefore, pollen grains were categorized based on spine morphology. Three components of the studied palynological characteristics were determined with PCA. The PCA results explained 78.79% of the variation, and polar diameter, equatorial diameter, diameter in polar view, exine thickness, intine thickness, pore length, colpus width, and spine length were found to be the most valuable palynological characteristics for discrimination of the Doronicum taxa. The HCA dendrogram also revealed three main clusters. This study is helpful for understanding the relationships among the taxa of Doronicum and provides insight for future taxonomic research.