Background and Aims Pteris (Pteridaceae), comprising over 250 species, had been thought to be a monophyletic genus until the three monotypic genera Neurocallis, Ochropteris and Platyzoma were included. However, the relationships between the type species of the genus Pteris, P. longifolia, and other species are still unknown. Furthermore, several infrageneric morphological classifications have been proposed, but are debated. To date, no worldwide phylogenetic hypothesis has been proposed for the genus, and no comprehensive biogeographical history of Pteris, crucial to understanding its cosmopolitan distribution, has been presented. Methods A molecular phylogeny of Pteris is presented for 135 species, based on cpDNA rbcL and matK and using maximum parsimony, maximum likelihood and Bayesian inference approaches. The inferred phylogeny was used to assess the biogeographical history of Pteris and to reconstruct the evolution of one ecological and four morphological characters commonly used for infrageneric classifications. Key Results The monophyly of Pteris remains uncertain, especially regarding the relationship of Pteris with Actiniopteris + Onychium and Platyzoma. Pteris comprises 11 clades supported by combinations of ecological and morphological character states, but none of the characters used in previous classifications were found to be exclusive synapomorphies. The results indicate that Pteris diversified around 47 million years ago, and when species colonized new geographical areas they generated new lineages, which are associated with morphological character transitions. Conclusions This first phylogeny of Pteris on a global scale and including more than half of the diversity of the genus should contribute to a new, more reliable infrageneric classification of Pteris, based not only on a few morphological characters but also on ecological traits and geographical distribution. The inferred biogeographical history highlights long-distance dispersal as a major process shaping the worldwide distribution of the species. Colonization of different niches was followed by subsequent morphological diversification. Dispersal events followed by allopatric and parapatric speciation contribute to the species diversity of Pteris.

The Pteris cadieri complex displays extensive morphological variation and seems to have originated through hybridization. However, the members of this complex reproduce by apogamy, which usually limits genetic variation. To evaluate the hypotheses of hybrid origins, the pattern of evolution in this species complex is reconstructed. Multiple methodologies were used. Diploids, triploids, and tetraploids were identified by chromosome counts and flow cytometry. Nuclear DNA markers (cytosolic phosphoglucose isomerase gene, PgiC) were used, together with chloroplast DNA markers (atpB-rbcL spacer and rbcL gene) to infer the biparental and maternal lineages of the Pteris cadieri complex. The three cpDNA haplotype groups and five PgiC alleles found in this study indicate that the evolution of the Pteris cadieri complex has been extremely reticulate. Up to 11 taxa belonging to eight morphs were identified. By comparing genetic variation in the Pteris cadieri in two independent areas, Hainan and Taiwan, we inferred that hybridization has occurred independently in different areas. Furthermore, we found evidence for phenological divergence (evergreen and deciduous) within Taiwan. We propose that the Pteris cadieri complex originated from different genetic lineages through multiple hybridizations in different geographical areas, leading to its present morphological diversity.

The highest frequency of polyploidy among plants is considered to occur in the Pteridophytes. In this study, we focused on polyploidy displayed by a specific fern taxon, the genus Pteris L. (Pteridaceae), comprising over 250 species. Cytological data from 106 Pteris species were reviewed. The base number of chromosomes in Pteris is 29. Polyploids are frequently found in Pteris, including triploids, tetraploids, pentaploids, hexaploids, and octoploids. In addition, an aneuploid species, P. deltodon Bak., has been recorded. Furthermore, the relationship between polyploidy and reproductive biology is reviewed. Among these 106 Pteris species, 60% exhibit polyploidy: 22% show intraspecific polyploidy and 38% result from polyploid speciation. Apogamous species are common in Pteris. Diploids are the most frequent among Pteris species, and they can be sexual or apogamous. Triploids are apogamous; tetraploids are sexual or apogamous. Most Pteris species have one to two ploidy levels. The diverse ploidy levels suggest that these species have a complex evolutionary history and their taxonomic problems require further clarification.

One genus (Chrysogrammitis) and twelve species (Asplenium pifongiae, Chrysogrammitis musgraviana, Crepidomanes makinoi, Ctenitis sinii, Ctenopterella khaoluangensis, Didymoglossum wallii, Dryopteris hendersonii, Hymenophyllum palmatifidum, H. paniculiflorum, Polystichum prionolepis, Pteris latipinna, and Stegnogramma wilfordii) of ferns are reported as new records for Vietnam based on newly collected specimens from Lang Biang Plateau. We provide photographs of key characters, type information, voucher specimens, distribution, ecology, and notes for each newly recorded species.

Pteris (Pteridaceae) spores are usually trilete and can be distinguished by the perine ornamentation. The systematic value of spore morphology in Pteris is unclear, especially based on the renewed infrageneric classification of Pteris. In the present study, we used scanning electron microscopy (SEM) to understand spore characters in 57 Pteris species, one Onychium species, and two Astrolepis species; 40 species are reported here for the first time. The observed spore characters combined with published spore data, totaling 100 species from 16 sections of Pteris, were mapped onto a reconstructed phylogenetic tree. Seven characters (five proposed in previous studies), including an equatorial flange, laesural ridges, proximal ridges, distal ridges, tubercula on distal faces, coarse reticula on distal faces, and a row of extervermiculi between the distal face and equatorial flange, were analyzed to investigate spore morphology evolution in Pteris. However, the results showed no synapomorphies with other genera in Pteridaceae. Most of the characters were found to have arisen independently several times in different lineages or were even frequently reversed. Equatorial flanges and tubercula on distal faces are plesiomorphies and present in most Pteris species. Overall, the application of spore morphology in section circumscription is limited. Thus, we suggest combining spore morphology with leaf characters for Pteris infrageneric classification.