Morphometric and Statistical Analysis of Pollen Morphology in Seven Woody Species of Betulaceae

Plants, cilt.15, sa.6, ss.1-14, 2026 (Hakemli Dergi)

Abstract

Morphological characteristics of pollen grains, including shape, size, pore number, and exine

thickness, vary significantly among species and enable the reliable use of palynological

data in taxonomic studies. In this context, the present study investigates the pollen morphology

of seven Betulaceae taxa (Alnus glutinosa, Betula pendula, Carpinus betulus, Carpinus

orientalis, Corylus avellana, Corylus colurna, and Ostrya carpinifolia). Detailed morphometric

measurements were carried out using Light Microscopy (LM), and high-resolution images

were obtained using Scanning Electron Microscopy (SEM). For each taxon, thirty measurements

were taken for the main pollen characters, including polar axis length (P), equatorial

diameter (E), pore length (plg), pore width (plt), and exine thickness (Ex). Interspecific

differences were evaluated using one-way ANOVA, Tukey’s HSD test, and Principal Component

Analysis (PCA), and a diagnostic pollen identification key was developed for the

investigated species. The results demonstrate statistically significant interspecific variation

in pollen size, pore characteristics, and exine thickness. In the PCA ordination, the first principal

component (PC1) was mainly associated with pollen size (P and E), clearly separating

Carpinus betulus from the remaining taxa. The second principal component (PC2) was primarily

related to pore length (plg) and contributed to the separation of Alnus glutinosa from

the other small-pollen species. These results show that quantitative pollen morphological

characters provide reliable criteria for distinguishing closely related Betulaceae taxa.