Osmundaceae is a family of ferns containing four to six extant genera and 18–25 known species. It is the only living family of the order Osmundales in the class Polypodiopsida (ferns) or in some classifications the only order in the class Osmundopsida. This is an ancient and fairly isolated group that is often known as the "flowering ferns" because of the striking aspect of the ripe sporangia in Claytosmunda, Osmunda, Osmundastrum, and Plensium. In these genera the sporangia are borne naked on non-laminar pinnules, while Todea and Leptopteris bear sporangia naked on laminar pinnules. Ferns in this family are larger than most other ferns.
Osmunda is a genus of primarily temperate-zone ferns of family Osmundaceae. Five to ten species have been listed for this genus.
Equisetales is an order of subclass Equisetidae with only one living family, Equisetaceae, containing the genus Equisetum (horsetails).
The order Salviniales is an order of ferns in the class Polypodiopsida.
Gleicheniales is an order of ferns in the subclass Polypodiidae. The Gleicheniales have records potentially as early as the Carboniferous, but the oldest unambiguous records date to the Permian.
Salviniaceae, is a family of heterosporous ferns in the order Salviniales. The Salviniaceae contain the two genera Azolla and Salvinia, with about 20 known species in total. The oldest records of the family date to the Late Cretaceous. Azolla was previously placed in its own family, Azollaceae, but research has shown Azolla and Salvinia to be sister genera with the likely phylogenic relationship shown in the following diagram.
The order Polypodiales encompasses the major lineages of polypod ferns, which comprise more than 80% of today's fern species. They are found in many parts of the world including tropical, semitropical and temperate areas.
Psilotaceae is a family of ferns consisting of two genera, Psilotum and Tmesipteris with about a dozen species. It is the only family in the order Psilotales.
Pteridaceae is a family of ferns in the order Polypodiales, including some 1150 known species in ca 45 genera, divided over five subfamilies. The family includes four groups of genera that are sometimes recognized as separate families: the adiantoid, cheilanthoid, pteridoid, and hemionitidoid ferns. Relationships among these groups remain unclear, and although some recent genetic analyses of the Pteridales suggest that neither the family Pteridaceae nor the major groups within it are all monophyletic, as yet these analyses are insufficiently comprehensive and robust to provide good support for a revision of the order at the family level.
Athyrium (lady-fern) is a genus of about 180 species of terrestrial ferns, with a cosmopolitan distribution. It is placed in the family Athyriaceae, in the order Polypodiales. Its genus name is from Greek a- ('without') and Latinized Greek thyreos ('shield'), describing its inconspicuous indusium . The common name "lady fern" refers in particular to the common lady fern, Athyrium filix-femina.
The Hymenophyllaceae, the filmy ferns and bristle ferns, are a family of two to nine genera and about 650 known species of ferns, with a subcosmopolitan distribution, but generally restricted to very damp places or to locations where they are wetted by spray from waterfalls or springs. A recent fossil find shows that ferns of Hymenophyllaceae have existed since at least the Upper Triassic.
Eusporangiate ferns are vascular spore plants, whose sporangia arise from several epidermal cells and not from a single cell as in leptosporangiate ferns. Typically these ferns have reduced root systems and sporangia that produce large amounts of spores.
The Polypodiidae, commonly called leptosporangiate ferns, formerly Leptosporangiatae, are one of four subclasses of ferns, the largest of these being the largest group of living ferns, including some 11,000 species worldwide. The group has also been treated as the class Pteridopsida or Polypodiopsida, although other classifications assign them a different rank. Older names for the group include Filicidae and Filicales, although at least the "water ferns" were then treated separately.
Saccolomataceae is a family of ferns in the order Polypodiales with about 19 species. It has been formerly treated as part of the Dennstaedtiaceae, however it has been classified as its own family according to Smith et al. (2006) The genus Saccoloma has been classified to include Orthiopteris, but the phylogeny of the group not yet fully understood. The family includes a dozen known species.
The forked ferns are the family Gleicheniaceae, which includes six genera and about 160 known species. The formerly independent families Dicranopteridaceae and Stromatopteridaceae are generally included in the Gleicheniaceae, whereas the Dipteridaceae and Matoniaceae, although closely related, are considered separate families by most authors.
Matoniaceae is one of the three families of ferns in the Gleicheniales order of the Polypodiopsida class. Fossil records reveal that Matoniaceae ferns were abundant during the Mesozoic era, during which they lived on every continent, including Antarctica, with eight genera and 26 species, with the oldest known specimens being from the Middle Triassic of Antarctica. Today the family is much less abundant, and also less diverse, with only two extant genera and four species, which are limited to portions of southeastern Asia.
Rhachidosorus is a genus of ferns in the order Polypodiales. It is the only genus in the family Rhachidosoraceae in the Pteridophyte Phylogeny Group classification of 2016. Alternatively, the genus may be placed in the subfamily Rhachidosoroideae of a more broadly defined family Aspleniaceae, the family placement used in Plants of the World Online as of November 2019.
Hymenasplenium is one of three genera of ferns in the Aspleniaceae, in the eupolypods II clade of the order Polypodiales. The others are Hemidictyum and Asplenium. Hymenasplenium was segregated because it is a natural grouping with differing rhizome morphology – dorsiventral v. radial for the rest of Asplenium, differing chromosome count – x=39 v. x=36 for the rest of Asplenium, and a clear monophyletic grouping based on genetic analysis. It was confirmed as a sister group to Asplenium in a 2015 molecular study of the genera.
Ophioglossidae is one of the four subclasses of Polypodiopsida (ferns). This subclass consists of the ferns commonly known as whisk ferns, grape ferns, adder's-tongues and moonworts. It is equivalent to the class Psilotopsida in previous treatments, including Smith et al. (2006). The subclass contains two orders, Psilotales and Ophioglossales, whose relationship was only confirmed by molecular phylogenetic studies.
Lindsaeineae is a suborder of ferns (Polypodiopsida), order Polypodiales, created by the Pteridophyte Phylogeny Group (2016). It consists of two monogeneric families plus the larger Lindsaeaceae with seven genera, and the suborder contains about 237 species overall. It corresponds to Lindsaeaceae sensu Smith 2016.
