In this study we address the phylogenetic relationships within the genus Hymenophyllum. Our sampling includes the segregate monotypic genera Cardiomanes, Serpyllopsis, Rosenstockia, and Hymenoglossum, representatives of the five subgenera proposed for Hymenophyllum by Morton, and of the section Microtrichomanes. Using morphology, cytology, and nucleotide sequences (rbcL, rps4-trnS, rbcL-accD), we obtained a fully resolved topology with several clades well supported. We confirm the monophyly of two clades within the Hymenophyllaceae. Serpyllopsis and Rosenstockia are nested in Hymenophyllum within a derived clade, while Cardiomanes and Hymenoglossum are positioned within a basal grade. Although some of the phylogenetic associations that were previously proposed within Hymenophyllum are supported, many traditionally defined infrageneric taxa are not resolved as monophyletic: subg. Hymenophyllum and Sphaerocionium are paraphyletic, and the broad subg. Mecodium, whose homogeneity had never been questioned, appears polyphyletic.
Of the 225 genera of pteridophytes listed in Kubitzki (1990) there are 131 (58%) genera with no known fungal association, according to the most comprehensive fungal database. The remaining 94 genera are represented by 524 taxa at the species and subspecies level which form about 1848 mainly parasitic interactions with 822 fungal taxa. Around 450 of these interactions are parasitic associations with rust fungi (Uredinales, Basidiomycetes), which are represented by four genera (and two form genera) and around 130 species and subspecies. Fungal synonymies have been resolved as far as possible, however, for this presentation pteridophyte synonymies have only partly been resolved, due to my lack of experience with ferns.
This paper examines the taxonomic distribution of fern – fungus interactions in general and the importance of the fern rusts in particular. Examples of interactions are illustrated with the aim of raising awareness among pteridologists and mycologists.
The neotropical genus Danaea is in revision and some notes on the genus are presented here. We find that the genus can be divided into three subgroups, based on morphological characters of the rhizome, stipe articulation and pinna margin serration. The tree groups are discussed and some taxonomic issues are addressed. The occurrence of bipinnate D. nodosa is reported from Jamaica, and trifoliate specimens of D. simplicifolia are reported from French Guiana. The identities of D. alata, D. jamaicensis, D. jenmanii, D. mazeana, D. media, D. nodosa, D. trifoliata and D. ulei and their synonyms are discussed. Further studies on the phylogeny, taxonomy and ecology of Danaea are needed.
A long-term demographic study to assess temporal variation in two common New England ferns, Dryopteris intermedia (Evergreen wood fern) and Polystichum acrostichoides (Christmas fern) focused on fertile leaf production by the reproductively mature sporophyte. Over an eight-year period only 29.9% of the leaves in a D. intermedia crown were fertile, while for P. acrostichoides significantly more (48.0%) of the leaves in the crown were fertile. Annual values of the percentage of plants with fertile leaves for D. intermedia ranged from 42% to 77% and for P. acrostichoides from 57% to 93% reflecting significant annual variation, possibly related to winter weather conditions. Only 16% of D. intermedia and 14% of P. acrostichoides sporophytes were fertile every year of the study. Transitions from fertile plant status to sterile plant status occurred in 15% of the D. intermedia observations and 14% of the P. acrostichoides observations. For both species, when a sterile year followed a fertile year the number of leaves in the crown decreased by approximately half a leaf. Determining the causes of such high levels of variability in plant fertility will be necessary before the role of ferns in any ecosystem can be fully understood.
This paper summarises our continuing study of the evolutionary history of Asplenium in New Zealand. Chloroplast DNA sequence data and AFLP DNA-fingerprinting have been used to examine the origins and relationships of the New Zealand Asplenium taxa, to test species boundaries, and to further investigate the ancestry of the octoploid Asplenium taxa belonging to the Austral group.