Over the last 50 years biosytematics and evolution of asplenioid ferns in North America and Europe have been extensively researched, using morphological comparison, cytology and allozyme electrophoresis. The outstanding studies of W. Wagner, C. Werth, I.Manton, J. Lovis and their co-authors uncovered networks of reticulate evolution in Europe and Eastern North America and thus provided good examples to study genetic aspects of this evolutionary mode using modern molecular methods. However, a comprehensive phylogeny of the genus Asplenium underpinning these biosystematic studies is still missing. The phylogeny of asplenioid ferns is studied using DNA sequence data of four chloroplast genome regions: two coding regions (rbcL and rps4) and two non-coding regions (trnL-F spacer and rps4-trnS spacer). About 100 species of the approximately 700 extant species of asplenioid ferns are included in this study. The taxon sampling covers nearly all putatively monophyletic groups such as Hymenasplenium, Ceterach, Loxoscaphe, and Phyllitis. The combined analyses of the four chloroplast genome regions result in a robust phylogenetic hypothesis for Asplenium s.l. Asplenioid ferns of the Northern temperate regions fall into three major clades and tropical asplenioid ferns are represented in an additional four major clades. In the northern temperate regions, hybrids and the resulting allotetraploids are often formed between diploid taxa nested within the same major clade and sometimes among diploid taxa nested in different major clades. The maternal components of hybrids are identified using this phylogeny because chloroplasts are exclusively inherited maternally. Thus, we can add a further corner stone to the understanding of the evolution of Asplenium in Northern America and Europe.

Key words: Aspleniaceae, biogeography, chloroplast DNA, ferns, hybrids, reticulate evolution