The endemic Parrotia persica, as dominant tree of forests in the lower belts, is the only species of the monotypic genus Parrotia. That underlies the exceptional plant-geographical position of the Hyrcanian forests within the deciduous broad-leaved forests of the Northern Hemisphere. The “sub-endemic” species like Zelkova carpinifolia, Pterocarya fraxinifolia and others are also very specific forest trees of the Hyrcanian-Colchic distribution type, which demonstrate the relations between the Hyrcanian and the Colchic relic forests (IUCN Consultation, 2020).