The epiphytic lichen flora of 37 stands of Platanus orientalis L. (plane) on the Greek mainland from Makedonia in the north to Peloponnisos in the south and in the W half of Kriti has been investigated. It is shown that a rich flora, including several members of the Collemataceae (12 taxa of Collema and 16 taxa of Leptogium), Gyalectaceae, Opegraphaceae and Pannariaceae, is more or less restricted to areas with high precipitation or sites with a humid mesoclimate, while under drier conditions P. orientalis supports mainly taxa of the families Lecanoraceae, Physciaceae and Teloschistaceae. However, elements of both species groups are present in most of the stands. Such a species combination may lend support to the S European Lobaria-Anaptychia nodum of the Lobarion proposed by Rose (1988). Riparian plane forests are discussed in relation to conservation of biodiversity. Among the 152 lichen taxa encountered, 13 taxa are new to Greece, viz.: Arthonia aff. stellaris, Bacidia absistens, Collema fragrans, C. ligerinum, Lecidella laureri, Lemmopsis cf. pelodes, Lepraria cf. imposibilis, Leptogium aragonii, L. microphylloides, L. pulvinatum var. quercicola, Opegrapha rufescens, Phaeophyscia chloantha and Rinodina anomala. A further ten taxa are new to the Greek mainland.