‘Structure and evolution of fern plastid genomes’, P. G. Wolf and J. M. Roper describe the progress in mapping the chloroplast genome. It is nearly 20 years since restriction mapping revealed that lycophytes lack an inverted repeat (IR) present in all other extant vascular plants. This approach has been succeeded by complete genome mapping (first achieved for Adiantum capillus-veneris in 2003 by Wolf et al.) and PCR mapping of the gene order of the IR sequence. Recent results have shown that the rare changes in the structure of the evolutionarily conservative IR provide phylogenetic data. Wolf and Roper describe the methodological approach and present previously unpublished results. New molecular techniques promise significant developments in the near future. The implications of the results will interest all pteridologists, even if the methods can be fully appreciated only by other molecular phylogeneticists.