The Pliocene flora of Frankfurt am Main described by Karl Mädler during the first half of the twentieth century is a key flora for the European Pliocene. In the present study, we revised the leaf fossil taxa described by Mädler and investigated plant material collected after Mädler’s publication. The revised and augmented floral list comprises seven new species and some new combinations of taxa described by Mädler. In total, 16 gymnosperm species in 15 genera and 73 angiosperm species (of which 15 could not be assigned to a genus) in 40 genera are recognised in the leaf record. Main characteristics of the flora are the high diversity of conifers, the diverse assemblage of exclusively deciduous Fagaceae, including six species of oaks, and the high diversity of Rosaceae. These features indicate cool temperate climatic conditions (comparable to Lugano in southern Switzerland). Angiosperm genera that are today confined to North America and/or East Asia (Eucommia, Magnolia and Sassafras) also are deciduous, whereas evergreen taxa are shrubs typical of the understorey (Buxus, Ilex, Pachysandra, Prunus lusitanica type) and Viscum. Eighteen taxa recorded in the Pliocene of Frankfurt am Main are today absent from western Eurasia and eastern North America, and 25 taxa are absent from western North America. This shows (i) a strong biogeographic link of the Pliocene flora of Frankfurt am Main with East Asia, (ii) surprisingly high levels of speciation (Pliocene endemisms) and (iii) that the European flora was more diverse in woody species shortly before the onset of major Pleistocene glaciations than today.

卡尔·梅德勒（KarlMädler）在20世纪上半叶描述的美因河畔法兰克福的上新世植物群是欧洲上新世的重要植物群。在本研究中，我们修订了Mädler描述的叶片化石分类单元，并研究了Mädler发表后收集的植物材料。修订后的花卉清单包括Mädler描述的七个新物种和一些新的分类单元组合。在叶记录中，总共识别出15个属中的16个裸子植物物种和40个属中的73个被子植物物种（其中15个不能被归为一个属）。该植物区系的主要特征是针叶树的高度多样性，落叶乔木科（包括6种橡树）的多样化组合以及蔷薇科的高多样性。这些特征表明凉爽的温带气候条件（与瑞士南部的卢加诺相比）。被子植物属目前仅限于北美和/或东亚（杜仲，木兰和S属植物也为落叶，而常绿的分类单元是典型的下层灌木（黄杨，冬青树，帕奇桑德拉，樱桃李型）和Viscum。今天在美因河畔法兰克福的上新世记录的18个分类单元不在欧亚大陆西部和北美东部，而在北美西部则没有25个分类单元。这表明（i）美因河畔法兰克福的上新世植物区系与东亚之间有很强的生物地理联系，（ii）令人惊讶的高物种形成（上新世地方病）和（iii）欧洲主要植物在更新世主要冰川爆发之前不久就比今天更加多样化。