Molecular phylogenetic studies have made it evident that similar fruit body types, formerly the cornerstone of the classification of ascomycete and basidiomycete fungi, including those that form lichens, are often a result of convergent evolution. This commentary provides an introduction to this special issue of Mycological Research, which is based on papers presented at a one-day joint meeting of the British Mycological Society and the Natural History Museum held in London on 3 December 2005. The nine papers included address this issue in relation to its impact on classification, and also draw attention to the over-emphasis in fungal classification of ascus types and, in the case of lichen fungi, thallus form.