| The Blechnaceae is a small family of derived leptosporangiate ferns. Both morphologically and cytologically complex, the phylogenetic relationships between the species are very poorly understood. I investigated the phylogenetic relationships in the family using molecular data derived from three chloroplast genes (rbcL, rps4, and the rps4-trnS intergenic spacer - 2222 characters, 1018 parsimony informative). I conducted both unequally weighted maximum parsimony and likelihood analyses. Each analysis yielded a single tree. In the consensus phylogeny derived from the two analyses, the woodwardioid ferns (Lorinseria, Anchistea, and Woodwardia ) diverge first clade, followed by the stenochlaenoid ferns ("Diafnia,´" Salpichlaena and Stenochlaena). True blechnoid ferns comprise the crown group, the terminal clades of which are divided into three general subgroups. The basal subclades include a morphologically and cytologically diverse assemblage of predominantly Laurasian species (Brainea, Sadleria , and four distinct lineages of Blechnum). The next major subgroup to diverge is a relatively species-rich clade the members of which share a distinct habit and a hemiepiphytic ecology. The terminal clade---the core blechnoids---comprise approximately twenty morphologically and cytologically distinct lineages, all of which are entirely or at least substantially Gondwanan in distribution. Although internal resolution within the crown group is poor, the resolved terminal clades are statistically well supported, and generally exhibit distinct morphologies and base chromosome numbers.; Detailed phylogenetic analyses of all twelve diploid species in the woodwardioid clade further support the monophyly of the group. Within the woodwardioid ferns, three major clades were resolved: Lorinseria, Anchistea, and Woodwardia. Lorinseria is the first to diverge and is monotypic. Anchistea, also monotypic, is sister to Woodwardia. Within Woodwardia, three subclades were resolved, all with good support. In contrast with most other Blechnaceae, the woodwardioid ferns are exclusively Laurasian. The extant species exhibit a classic Arcto-Tertiary distribution pattern, with individual species scattered throughout North America, Asia and Europe. The group appears to have first evolved in North America, where today both Lorinseria and Anchistea are endemic. |
