Pollen morphology of Verbascum (Scrophulariaceae) in Tu<euro>rkiye and its systematic implication

The genus Verbascum L. is represented by 257 taxa under 13 artificial groups in Turkiye. No study has evaluated the relevance of artificial grouping to pollen morphological data. The main aim of this study is the palynological characterization of Verbascum taxa that occur naturally in Turkiye. In this context, the pollen morphology of 32 Verbascum taxa, 11 of which are endemic, was researched in detail by light microscopy and scanning electron microscopy. Moreover, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were performed to identify closely related species and palynological characters that could be effectively employed to distinguish the studied taxa. Tricolpate pollen grains were observed in all studied taxa, but varying proportions of tricolporate pollen aperture types (rarely tetracolpate/tetracolporate) were also detected. Pollen shapes range from suboblate to prolate, all exhibiting a circular amb. Three types of ornamentation were identified in the SEM study. Two components of the studied palynological characteristics were defined using PCA. PCA explains 81.18% of the variation, and equatorial diameter, diameter in polar view, the distance between two colpi, colpus length, and polar diameter were found to be the most valuable palynological characteristics for discrimination of the Verbascum taxa. The HCA dendrogram revealed three main clusters. The discrepancy between pollen morphology and the artificial grouping of taxa was noted. Considering the taxonomic difficulty of the genus and the paucity of morphological characters that do not allow the establishment of infrageneric categories, this pollen study may contribute to the systematics of the genus and the identification of closely related species. (c) 2025 SAAB. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.