| Polypodiales Temporal range: | |
|---|---|
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| Polypodium californicum | |
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Division: | Polypodiophyta |
| Class: | Polypodiopsida |
| Subclass: | Polypodiidae |
| Order: | Polypodiales Link (1833) |
| Suborders [1] | |
6. See text | |
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.
Polypodiales are unique in bearing sporangia with a vertical annulus interrupted by the stalk and stomium. [2] These sporangial characters were used by Johann Jakob Bernhardi to define a group of ferns he called the "Cathetogyratae"; [3] the Pteridophyte Phylogeny Group has suggested reviving this name as the informal term cathetogyrates, to replace the ambiguously circumscribed term "polypods" when referring to the Polypodiales. [1] The sporangia are born on stalks 1–3 cells thick and are often long-stalked. [2] (In contrast, the Hymenophyllales have a stalk composed of four rows of cells.) [4] The sporangia do not reach maturity simultaneously. Many groups in the order lack indusia, but when present, they are attached either along the edge of the indusium or in its center. [2]
Both Polypodiales and Cyatheales differ from other ferns in having a photoreceptor called a neochrome, which allows them to perform photosynthesis better in low-light conditions, such as in the shadows on the forest floor. The common ancestor of the two groups appears to have derived the neochrome via horizontal gene transfer from a hornwort. [5]
Their gametophytes are green, usually heart-shaped, and grow at the surface [2] (rather than underground, as in Ophioglossales). [6]
The order Polypodiales was first described by Link in 1833. [1] The circumscription of the order has changed over time as ferns have been classified in many different ways (see the review by Christenhusz and Chase, 2014). [7] Smith et al. (2006) carried out the first higher-level pteridophyte classification published in the molecular phylogenetic era. [8] They referred to the ferns (now including horsetails) as monilophytes, dividing them into four groups, with the vast majority of species being placed in a taxon they called "Polypodiopsida". The four-fold grouping has persisted through subsequent systems, despite changes in nomenclature. [9] [10] [7] [1] Polypodiopsida is now used for all ferns (sensu lato), [1] with Smith et al.'s group being subclass Polypodiidae. This group, which includes Polypodiales, is also informally known as the leptosporangiate ferns, while the remaining three groups (subclasses) are referred to as eusporangiate ferns. The Polypodiidae have been divided into seven orders, Polypodiales being the largest. The phylogenetic position of Polypodiales in relation to the other orders of Polypodiidae is shown in the following cladogram. [1]
| Subclass Polypodiidae |
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Despite being the most diverse order of ferns, they appeared relatively late in the evolutionary history of the group, during the Early Cretaceous, and diversified substantially throughout the period. [11]
The division of the Polypodiales into families has changed somewhat between the pioneering work of Smith et al. (2006) and the Pteridophyte Phylogeny Group's classification of 2016, with a general increase in the number of divisions recognized, albeit sometimes at different ranks. The table below summarizes four systems; families are listed alphabetically within three broad groups. Although the same families are used in more than one system, circumscriptions may differ. Christenhusz and Chase in 2014 used a very broad circumscription of Aspleniaceae and Polypodiaceae, reducing families used in other systems to subfamilies.
| Smith et al. (2006) [8] | Christenhusz et al. (2011) [10] | Christenhusz & Chase (2014) [7] | PPG I (2016) [1] | |
|---|---|---|---|---|
| Basal families | – | Cystodiaceae | Cystodiaceae | Cystodiaceae |
| Dennstaedtiaceae | Dennstaedtiaceae | Dennstaedtiaceae | Dennstaedtiaceae | |
| Lindsaeaceae | Lindsaeaceae | Lindsaeaceae | Lindsaeaceae | |
| – | Lonchitidaceae | Lonchitidaceae | Lonchitidaceae | |
| Pteridaceae | Pteridaceae | Pteridaceae | Pteridaceae | |
| Saccolomataceae | Saccolomataceae | Saccolomataceae | Saccolomataceae | |
| Aspleniineae eupolypods II (Aspleniaceae) | Aspleniaceae | Aspleniaceae | Aspleniaceae: Asplenioideae | Aspleniaceae |
| – | Athyriaceae | Aspleniaceae: Athyrioideae | Athyriaceae | |
| Blechnaceae | Blechnaceae | Aspleniaceae: Blechnoideae | Blechnaceae | |
| – | Cystopteridaceae | Aspleniaceae: Cystopteridoideae | Cystopteridaceae | |
| – | – | – | Desmophlebiaceae | |
| – | Diplaziopsidaceae | Aspleniaceae: Diplaziopsidoideae | Diplaziopsidaceae | |
| – | – | – | Hemidictyaceae | |
| Onocleaceae | Onocleaceae | – | Onocleaceae | |
| – | Rhachidosoraceae | Aspleniaceae: Rhachidosoroideae | Rhachidosoraceae | |
| Thelypteridaceae | Thelypteridaceae | Aspleniaceae: Thelypteridoideae | Thelypteridaceae | |
| Woodsiaceae | Woodsiaceae | Aspleniaceae: Woodsioideae | Woodsiaceae | |
| Polypodiineae eupolypods I (Polypodiaceae) | Davalliaceae | Davalliaceae | Polypodiaceae: Davallioideae | Davalliaceae |
| – | – | Polypodiaceae: Didymochlaenoideae | Didymochlaenaceae | |
| Dryopteridaceae | Dryopteridaceae | Polypodiaceae: Dryopteridoideae | Dryopteridaceae | |
| – | Hypodematiaceae | Polypodiaceae: Hypodematioideae | Hypodematiaceae | |
| Lomariopsidaceae | Lomariopsidaceae | Polypodiaceae: Lomariopsidoideae | Lomariopsidaceae | |
| – | Nephrolepidaceae | – | Nephrolepidaceae | |
| Oleandraceae | Oleandraceae | Polypodiaceae: Oleandroideae | Oleandraceae | |
| Polypodiaceae | Polypodiaceae | Polypodiaceae: Polypodioideae | Polypodiaceae | |
| Tectariaceae | Tectariaceae | Polypodiaceae: Tectarioideae | Tectariaceae |
Smith et al. (2006) divided the Polypodiales into fifteen families, [8] a practice continued in their 2008 revision, [12] with members of the eupolypods placed in two unranked clades. The families are listed in the table. While many of these families had previously been recognized with similar circumscriptions, the authors noted that Dryopteridaceae was more narrowly bounded than in historical circumscriptions, which had included their Tectariaceae, Onocleaceae and Woodsiaceae. The circumscription of Lomariopsidaceae changed dramatically, with most historical genera of that family (except Lomariopsis and Thysanosoria ) being moved to Dryopteridaceae, while Cyclopeltis and Nephrolepis were added. Saccolomataceae were removed from the dennstaedtioids. Cystodium was tentatively placed in Lindsaeaceae, away from its historical position with the tree ferns. Woodsiaceae was acknowledged to be of uncertain circumscription and perhaps paraphyletic; the inclusion of Hypodematium , Didymochlaena , and Leucostegia perhaps also rendering Dryopteridaceae paraphyletic. The grammitids were included in Polypodiaceae to render that family monophyletic. [8]
The linear sequence of Christenhusz et al. (2011), intended for compatibility with the classification of Chase and Reveal (2009), [9] incorporated new phylogenetic evidence to make several changes at the familial level, resulting in an expansion to 23 families. Lonchitis and Cystodium were removed from the Lindsaeaceae and incorporated into new families, Lonchitidaceae and Cystodiaceae respectively. Within eupolypods I, Woodsiaceae proved to be paraphyletic and was reduced to the genera Cheilanthopsis, Hymenocystis, and Woodsia, while the remainder of its genera were removed to Cystopteridaceae, Diplaziopsidaceae, Rhachidosoraceae, Athyriaceae, and Hemidictyaceae. Within eupolypods II, Nephrolepis was placed in a new family, the Nephrolepidaceae, due to uncertainty in its phylogenetic placement, while Hypodematiaceae was split from Dryopteridaceae to contain the three problematic genera mentioned by Smith et al. [10]
The classification of Christenhusz and Chase (2014) dramatically reduced the number of families recognized in this order to eight by "lumping", reducing many families to subfamilies and expanding the circumscription of Polypodiaceae and Aspleniaceae to encompass all of eupolypods I and eupolypods II, respectively. Former families became subfamilies (see the table above). The former Hemidictyaceae were included in the Asplenioideae, and the Onocleaceae in the Blechnoideae. In the new Polypodiaceae, Didymochlaena was placed in its own subfamily, Didymochlaenoideae. [7]
The PPG I classification (2016) used a process intermediate between the two previous approaches, by introducing a new rank, that of suborder, and organising 26 families (in some cases very narrowly circumscribed) into six suborders, largely returning to the families set out by Christenhusz et al. in 2011. In lieu of the expansion of Aspleniaceae and Polypodiaceae, eupolypods I and II were recognized and named as suborders: [1] [7]
| Pteridophyte Phylogeny Group 2016 [1] | Nitta et al. 2022 [13] and Fern Tree of life [14] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Now-obsolete families of Polypodiales include:
Polypodiales may be regarded as one of the most evolutionarily advanced orders of monilophytes (ferns), based on recent genetic analysis. They arose and diversified about 100 million years ago, probably subsequent to the diversification of the angiosperms. [15]
The Aspleniaceae (spleenworts) are a family of ferns, included in the order Polypodiales. The composition and classification of the family have been subject to considerable changes. In particular, there is a narrow circumscription, Aspleniaceae s.s., in which the family contains only two genera, and a very broad one, Aspleniaceae s.l., in which the family includes 10 other families kept separate in the narrow circumscription, with the Aspleniaceae s.s. being reduced to the subfamily Asplenioideae. The family has a worldwide distribution, with many species in both temperate and tropical areas. Elongated unpaired sori are an important characteristic of most members of the family.
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.
The Dryopteridaceae are a family of leptosporangiate ferns in the order Polypodiales. They are known colloquially as the wood ferns. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the family is placed in the suborder Polypodiineae. Alternatively, it may be treated as the subfamily Dryopteridoideae of a very broadly defined family Polypodiaceae sensu lato.
A pteridophyte is a vascular plant that reproduces by means of spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as "cryptogams", meaning that their means of reproduction is hidden.
Blechnaceae is a family of ferns in the order Polypodiales, with a cosmopolitan distribution. Its status as a family and the number of genera included have both varied considerably. In the Pteridophyte Phylogeny Group classification of 2016, the family has 24 genera, and excludes genera placed in the separate family Onocleaceae. The family is divided into three subfamilies, including Blechnoideae s.s. Alternatively, the entire family may be treated as the subfamily Blechnoideae s.l. of a very broadly defined family Aspleniaceae, and include genera others place in Onocleaceae.
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.
The Athyriaceae are a family of terrestrial ferns in the order Polypodiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the family is placed in the suborder Aspleniineae, and includes two genera. Alternatively, it may be treated as the subfamily Athyrioideae of a very broadly defined family Aspleniaceae. The family has with a cosmopolitan distribution.
Onocleaceae is a small family of terrestrial ferns in the order Polypodiales. It is placed in the suborder Aspleniineae in the Pteridophyte Phylogeny Group classification of 2016. Alternatively, the family, along with Blechnaceae, may be placed in a very broadly defined family Aspleniaceae as the subfamily Blechnoideae. The family may contain from one to four genera, consisting of five species largely in north temperate climes. The four genera, Matteuccia, Onoclea, Onocleopsis and Pentarhizidium, may be included under the single genus Onoclea.
Aspleniineae is a suborder of ferns in the order Polypodiales. It is equivalent to the clade eupolypods II in earlier systems; it is also treated as a single very broadly defined family Aspleniaceae. The suborder generally corresponds with the order Blechnales as described by J. L. Reveal in 1993. Aspleniineae includes some important ferns, including Onoclea sensibilis, the sensitive fern, which grows as a virtual weed throughout much of its temperate North American range, and ferns of the genus Thelypteris, a genus that has shown remarkable speciation. It also includes one of the more common horticultural ferns, Matteuccia struthiopteris, the ostrich fern.
Lindsaeaceae is a pantropical family of ferns in the order Polypodiales. It contains six or seven genera with about 220 known species, some of which also extend into the more temperate regions of eastern Asia, New Zealand, and South America.
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.
Cystopteridaceae is a family of ferns in the order Polypodiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the family is placed in the suborder Aspleniineae of the order Polypodiales, and includes three genera. Alternatively, it may be treated as the subfamily Cystopteridoideae of a very broadly defined family Aspleniaceae.
Hypodematiaceae is a family of ferns in the order Polypodiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the family is placed in the suborder Polypodiineae. Alternatively, it may be treated as the subfamily Hypodematioideae of a very broadly defined family Polypodiaceae sensu lato. The family consists of two, or in some versions three, small genera.
Tectariaceae is a family of leptosporangiate ferns in the order Polypodiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the family is placed in the suborder Polypodiineae. Alternatively, it may be treated as the subfamily Tectarioideae of a very broadly defined family Polypodiaceae sensu lato. The family comprises seven genera, of which Tectaria is by far the largest.
Polypodioideae is a subfamily belonging to the fern family Polypodiaceae, which is a member of the suborder Polypodiineae in the Pteridophyte Phylogeny Group classification of 2016 (PPG I). Alternatively, the subfamily may be treated as the tribe Polypodieae within a very broadly defined family Polypodiaceae sensu lato.
Polypodiineae is a suborder of ferns in the order Polypodiales. It is equivalent to the clade eupolypods I in earlier systems, and to the very broadly defined family Polypodiaceae in the classification of Christenhusz & Chase (2014). It probably diverged from the suborder Aspleniineae during the mid-Cretaceous. The divergence is supported by both molecular data and an often overlooked morphological characteristic which lies in the vasculature of the petiole. Most species that make up the suborder have three vascular bundles. The only exceptions are the grammitid ferns which have one, and the genus Hypodematium which has two. This differs from eupolypods II which mostly have two vascular bundles.
Diplaziopsidaceae is a family of ferns in the order Polypodiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the family is placed in the suborder Aspleniineae, and includes two genera. Alternatively, it may be treated as the subfamily Diplaziopsidoideae of a very broadly defined family Aspleniaceae.
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.
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