The fern family Blechnaceae is cosmopolitan; however, the vast majority of species are placed in Blechnum, which occurs predominantly in the Southern Hemisphere. There are two areas that are particularly species–rich: the south–west Pacific (including Australasia), and Central and South America. Using chloroplast DNA sequences, we report the first comprehensive phylogenetic analysis of the Blechnaceae, including all genera widely recognised in recent treatments, and over half of the species. There is strong support for several major clades, which we characterise morphologically and geographically, and some of their interrelationships. Blechnum is confirmed as polyphyletic. Blechnum indicum and B. serrulatum are more closely related to Salpichlaena and Stenochlaena, and are segregated as a new genus, Telmatoblechnum. Alternative generic circumscriptions are discussed for the remainder of Blechnum. In the absence of morphological characters to diagnose the clades within core Blechnum, and for the sake of taxonomic stability, we advocate a broad circumscription for Blechnum. Brainea and Sadleria are retained as their relationships are not well resolved, but Doodia and Pteridoblechnum are clearly nested within the core of Blechnum and we provide four new names in Blechnum. Additionally, given the focus of our sampling, we discuss the biogeography of the south–west Pacific, where immigration has been more important in community assembly than what might be superficially inferred from patterns of endemism (with ca. 60% of species endemic to individual land areas).

Previous molecular phylogenetic analyses have resolved the Australian bloodwood eucalypt genus Corymbia (~100 species) as either monophyletic or paraphyletic with respect to Angophora (9–10 species). Here we assess relationships of Corymbia and Angophora using a large dataset of chloroplast DNA sequences (121,016 base pairs; from 90 accessions representing 55 Corymbia and 8 Angophora species, plus 33 accessions of related genera), skimmed from high throughput sequencing of genomic DNA, and compare results with new analyses of nuclear ITS sequences (119 accessions) from previous studies. Maximum likelihood and maximum parsimony analyses of cpDNA resolve well supported trees with most nodes having >95% bootstrap support. These trees strongly reject monophyly of Corymbia, its two subgenera (Corymbia and Blakella), most taxonomic sections (Abbreviatae, Maculatae, Naviculares, Septentrionales), and several species. ITS trees weakly indicate paraphyly of Corymbia (bootstrap support <50% for maximum likelihood, and 71% for parsimony), but are highly incongruent with the cpDNA analyses, in that they support monophyly of both subgenera and some taxonomic sections of Corymbia. The striking incongruence between cpDNA trees and both morphological taxonomy and ITS trees is attributed largely to chloroplast introgression between taxa, because of geographic sharing of chloroplast clades across taxonomic groups. Such introgression has been widely inferred in studies of the related genus Eucalyptus. This is the first report of its likely prevalence in Corymbia and Angophora, but this is consistent with previous morphological inferences of hybridisation between species. Our findings (based on continent-wide sampling) highlight a need for more focussed studies to assess the extent of hybridisation and introgression in the evolutionary history of these genera, and that critical testing of the classification of Corymbia and Angophora requires additional sequence data from nuclear genomes.

Aim We investigated genetic divergence among two widespread eastern Australian orchids (Dendrobium sect. Dendrocoryne): Dendrobium speciosum and Dendrobium tetragonum. These orchids are endemic to mesic habitats, with distributional ranges that cross major geographical breaks associated with deep divergences in various fauna. We compared the biogeography of these orchids with other taxa and tested for congruence of divergence date estimations. Location Eastern Australia, latitude 14° S to 34° S. Methods Phylogenetic relationships within each species were estimated using maximum parsimony based on sequences of internal transcribed spacer (ITS) regions of nuclear ribosomal DNA and the psbA–trnH spacer region of plastid DNA. Divergence dates were inferred by Bayesian relaxed‐clock dating, calibrated on an early Miocene macrofossil, Dendrobium winikaphyllum from New Zealand. Results Deep divergences were revealed within each species. Dendrobium speciosum includes three major geographical clades (deepest 2.6% ITS divergence): a northern Queensland clade, which occurs mainly to the north of the Black Mountain Corridor (BMC) in the Wet Tropics; a central Queensland clade; and a southern clade related to the central clade and separated from it by a dry corridor, the St Lawrence Gap (SLG). The central and northern lineages show overlap near the BMC. Divergence in this area is estimated to date from the Pliocene, possibly late Miocene, 4.3 (2.0–6.9) Ma, and at the SLG in the early Pleistocene, possibly late Pliocene, 2.0 (0.6–3.8) Ma. Dendrobium tetragonum also includes two clades, deeply divergent (3%) at the SLG, estimated as Pliocene in age but possibly latest Miocene, 3.7 (1.8–5.9) Ma. Main conclusions Dendrobium orchids reveal significant divergence associated with geographical breaks in eastern Australia, the SLG and BMC, patterns broadly concordant with findings for fauna. We infer that divergences were driven by topographical and climatic conditions, with contraction and fragmentation of mesic biomes during periods of drying in the late Neogene.

Philotheca sect. Erionema includes 14 species from eastern Australia and one from south-western Australia. We conducted a phylogenetic analysis of the section, including samples of all species, using sequences of the ITS and ETS regions of nuclear ribosomal DNA. Results were broadly congruent with a previous analysis based on morphological and flavonoid data. The analysis is consistent with the monophyly of the section and supports the monophyly of six species represented by multiple samples. Philotheca verrucosa (A. Rich.) Paul G. Wilson was resolved as paraphyletic with respect to P. freyciana Rozefelds but with poor support. Philotheca glasshousiensis, P. myoporoides and P. myoporoides subsp. myoporoides were clearly polyphyletic, including separate geographic clades and the classification of each of these taxa requires revision. In particular, disjunct northern populations of P. glasshousiensis probably represent a distinct species, the five subspecies of P. myoporoides could be treated as separate species and at least two other distinct groups that are currently included under the circumscription of subsp. myoporoides could be treated as species. The phylogeny revealed deeply divergent, geographically overlapping clades in eastern Australia and substantial distances (up to 900 km) between sister taxa. We infer that biogeography of the group has been shaped largely by vicariant differentiation of taxa.