The palynomorphological characteristics of 5 species belonging to Hedera of
the Araliaceae family were studied in detail. These plant species were
collected from various phytogeographical regions of Iran and Hungary. The
palynological investigation was accomplished using Transmission Electron
Microscope (TEM) and Scanning Electron Microscope (SEM). Pollen grains of
the species are reticulate, prolate, sub-prolate, tricolporate, isopolar,
radially symmetrical, and monad. The largest pollen grain was in the Hedera
colchica species (72.24?1.6 ?m) and the smallest pollen grain was in Hedera
helix (28.63?2.1 ?m). The research carried out by the TEM showed that the
species were different in terms of exine thickness, tectum thickness, foot
layer thickness, the diameter and length of the Columella, the thickness and
shape of the Caput, the tectum to foot layer )T/F( ratio, the absence or
presence of the Endexine and the thickness of the Intine layers. The main
purpose of this study was the importance of the relationship between pollen
grain size and the number of chromosomes and ploidy level in Hedera species.