The pollen size among the species studied ranges from 16.2-32.5 μm. The majority of species are medium sized except V. agrimoniifolium and V. oreophilum that are small sized, and four species i.e. V. palmyrense, V. sinuatum, V. songaricum, and V. thapsus having both small and medium sized pollen grains.
Moreover, the result showed that the exine thickness ranges from 0.87-4.75 μm, but this value can overlap between some species. Therefore, only the shape of pollen grains could be used to classify these species into groups.