In this study, the pollen morphology of 13 taxa of the genus Onobrychis Mill. (Onobrychis arenaria (Kit.) DC. subsp. arenaria, O. inermis Steven, O. petraea (M.Bieb.ex Willd.) Fisch., O. alba (Waldst. & Kit.) Desv. subsp. laconica (Boiss.) Hayek, O. megataphros Boiss., O. oxyodonta Boiss., O. cyri Grossh., O. biebersteinii Širj., O. vassilczenkoi Grossh., O. grandis Lipsky, O. hypargyrea Boiss., O. kemulariae Chinth. and O. caput-galli (L.) Lam.) grown in the experimental field was examined by light microscopy (LM). Slides were prepared according to the glycerin-jelly method of Wodehouse. Pollen grains were trizonocolpate, radially symmetrical, and isopolar in all taxa. The pollen shape was prolate. The amb was almost circular. All the pollen grains were medium in size, with the largest belonging to O. cyri (P × E = 36.55 × 21.60) and the smallest belonging to O. vassilczenkoi (P × E = 28.67 × 18.48). The colpus was in the form of a long, narrow slit. Exine ornamentation was reticulate. Based on quantitative data, the species were categorized and separated using principle component analysis (PCA).