Ascomycete fungi, identified cytologically from their simple septa and Woronin bodies and genetically diagnosed as belonging to the Rhizoscyphus ericae (D. J. Read) W. Y. Zhuang & Korf (Hymenoscyphus ericae (D. J. Read) Korf & Kernan) aggregate form a range of specialized mutualistic associations with the rhizoids in several families of leafy liverworts. To test the hypothesis that this fungus can produce these associations between liverworts from widely separate geographical regions, we carried out cross-infection experiments between mycobionts that induce branching and septation in the rhizoids in the Schistochilaceae from the southern hemisphere and those from a range of disparate taxa (Bazzania, Calypogeia, Cephalozia, Kurzia, Lepidozia, Odontoschisma) from the northern hemisphere and from Calluna in the Ericaceae. All the fungal isolates produced rhizoid infections identical to those found in nature. The same fungal isolates also invaded the rhizoids of axenically cultured Nardia scalaris, whose stems in nature harbor a basidiomycete and the fungus-free species Jungermannia gracillima, but balanced relationships in these cross infection experiments were not established. Consideration of recent liverwort phylogenies placing the Sch istochilaceae as sister to all the other fungus-containing clades of leafy liverworts, together with dating of this family in the Triassic, suggests that liverwort–ascomycete associations may have pre-dated ericoid mycorrhizas. However, the diverse cytology of these associations and their discontinuous distribution between families in the leafy liverworts indicate more recent and multiple origins including host swapping from the Ericales.