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44-469: Osmundaceae (royal fern family) 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 (known from the Upper Permian ) and fairly isolated group that is often known as the "flowering ferns" because of

88-734: A class Equisetopsida ( Embryophyta ) encompassing all land plants. This is referred to as Equisetopsida sensu lato to distinguish it from the narrower use to refer to horsetails alone, Equisetopsida sensu stricto . They placed the lycopods into subclass Lycopodiidae and the ferns, keeping the term monilophytes, into five subclasses, Equisetidae, Ophioglossidae, Psilotidae, Marattiidae and Polypodiidae, by dividing Smith's Psilotopsida into its two orders and elevating them to subclass (Ophioglossidae and Psilotidae). Christenhusz et al. (2011) followed this use of subclasses but recombined Smith's Psilotopsida as Ophioglossidae, giving four subclasses of ferns again. Christenhusz and Chase (2014) developed

132-628: A few species (e.g., Cyathea brownii on Norfolk Island and Cyathea medullaris in New Zealand ). Roots are underground non-photosynthetic structures that take up water and nutrients from soil . They are always fibrous and are structurally very similar to the roots of seed plants. As in all vascular plants , the sporophyte is the dominant phase or generation in the life cycle . The gametophytes of ferns, however, are very different from those of seed plants. They are free-living and resemble liverworts , whereas those of seed plants develop within

176-405: A group of vascular plants (plants with xylem and phloem ) that reproduce via spores and have neither seeds nor flowers . They differ from mosses by being vascular, i.e., having specialized tissues that conduct water and nutrients, and in having life cycles in which the branched sporophyte is the dominant phase. Ferns have complex leaves called megaphylls that are more complex than

220-483: A new classification of ferns and lycopods. They used the term Polypodiophyta for the ferns, subdivided like Smith et al. into four groups (shown with equivalents in the Smith system), with 21 families, approximately 212 genera and 10,535 species; This was a considerable reduction in the number of families from the 37 in the system of Smith et al., since the approach was more that of lumping rather than splitting. For instance

264-844: A number of families were reduced to subfamilies. Subsequently, a consensus group was formed, the Pteridophyte Phylogeny Group (PPG), analogous to the Angiosperm Phylogeny Group , publishing their first complete classification in November 2016. They recognise ferns as a class, the Polypodiopsida, with four subclasses as described by Christenhusz and Chase, and which are phylogenetically related as in this cladogram: Equisetales Ophioglossales Psilotales Marattiales Osmundales Hymenophyllales Gleicheniales Schizaeales Sister group The expression

308-462: A protective coating called an indusium . The arrangement of the sporangia is important in classification. In monomorphic ferns, the fertile and sterile leaves look morphologically the same, and both are able to photosynthesize. In hemidimorphic ferns, just a portion of the fertile leaf is different from the sterile leaves. In dimorphic (holomorphic) ferns, the two types of leaves are morphologically distinct . The fertile leaves are much narrower than

352-521: A ring of phloem occurs on the outside only of a ring of xylem , which surrounds pith (and no other vascular tissue). Stipules can be discerned at the leaf bases of these ferns. The hardened leaf bases are persistent and overlap to form a hardened layer surrounding the stem. The mantle of sclerenchymatous leaf bases and intermixed roots can form a woody trunk when the stem emerges above ground, up to 1 meter (3.3 ft) in Todea barbara . Extinct members of

396-430: A short-lived structure anchored to the ground by rhizoids called gametophyte which produce gametes. When a mature fertile frond bears sori, and spores are released, the spores will settle on the soil and send out rhizoids , while it develops into a prothallus . The prothallus bears spherical antheridia ( s.g. antheridium ) which produce antherozoids (male gametophytes) and archegonia ( s.g. archegonium ) which release

440-568: A single oosphere . The antherozoid swims up the archegonium and fertilize the oosphere, resulting in a zygote, which will grow into a separate sporophyte, while the gametophyte shortly persists as a free-living plant. Carl Linnaeus (1753) originally recognized 15 genera of ferns and fern allies, classifying them in class Cryptogamia in two groups, Filices (e.g. Polypodium ) and Musci (mosses). By 1806 this had increased to 38 genera, and has progressively increased since ( see Schuettpelz et al (2018) ). Ferns were traditionally classified in

484-493: Is polyphyletic , the term fern allies should be abandoned, except in a historical context. More recent genetic studies demonstrated that the Lycopodiophyta are more distantly related to other vascular plants , having radiated evolutionarily at the base of the vascular plant clade , while both the whisk ferns and horsetails are as closely related to leptosporangiate ferns as the ophioglossoid ferns and Marattiaceae . In fact,

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528-578: Is intermediate between the eusporangiate ferns and the leptosporangiate ferns. Rai and Graham (2010) broadly supported the primary groups, but queried their relationships, concluding that "at present perhaps the best that can be said about all relationships among the major lineages of monilophytes in current studies is that we do not understand them very well". Grewe et al. (2013) confirmed the inclusion of horsetails within ferns sensu lato , but also suggested that uncertainties remained in their precise placement. Other classifications have raised Ophioglossales to

572-417: Is most easily illustrated by a cladogram :   Taxon A       Taxon B       Taxon C               More tree branches   Taxon A and taxon B are sister groups to each other. Taxa A and B, together with any other extant or extinct descendants of their most recent common ancestor (MRCA), form a monophyletic group,

616-613: Is present, it is found in the stem. Their foliage may be deciduous or evergreen , and some are semi-evergreen depending on the climate. Like the sporophytes of seed plants, those of ferns consist of stems, leaves and roots. Ferns differ from spermatophytes in that they reproduce by spores rather than having flowers and producing seeds. However, they also differ from spore-producing bryophytes in that, like seed plants, they are polysporangiophytes , their sporophytes branching and producing many sporangia. Also unlike bryophytes, fern sporophytes are free-living and only briefly dependent on

660-630: Is shown in the following cladogram , where Osmundales is seen as a sister to all other members of the subclass. Osmundales Hymenophyllales Gleicheniales Schizaeales Salviniales Cyatheales Polypodiales In the Pteridophyte Phylogeny Group classification (2016) Osmundales consists of the single family Osmundaceae, six genera, and an estimated 18 species (Christenhusz and Byng give 25 species). The three genera Osmunda , Leptopteris , and Todea were recognized as members of Osmundaceae by Smith et al. (2006) Of these,

704-857: The Triassic and was finished by the Early Cretaceous with the formation of Osmunda and Plenasium . Accordingly, the PPG I classification of 2016 continues to place Osmundales in Polypodiidae, but splits Osmunda further by elevating its subgenera to genera ( Claytosmunda , Plenasium ). The following cladogram reproduces the PPG I concept for the extant members of the family: Osmundastrum (Alternative A: outgroup-inferred root in multigene trees) Todea Leptopteris Osmundastrum (Alternative B) Claytosmunda (= Osmunda claytoniana ) Plenasium 4 species Osmunda 4 species The new system

748-564: The clade AB. Clade AB and taxon C are also sister groups. Taxa A, B, and C, together with all other descendants of their MRCA form the clade ABC. The whole clade ABC is itself a subtree of a larger tree which offers yet more sister group relationships, both among the leaves and among larger, more deeply rooted clades. The tree structure shown connects through its root to the rest of the universal tree of life . In cladistic standards, taxa A, B, and C may represent specimens, species , genera , or any other taxonomic units. If A and B are at

792-472: The class Filices, and later in a Division of the Plant Kingdom named Pteridophyta or Filicophyta. Pteridophyta is no longer recognised as a valid taxon because it is paraphyletic . The ferns are also referred to as Polypodiophyta or, when treated as a subdivision of Tracheophyta (vascular plants), Polypodiopsida, although this name sometimes only refers to leptosporangiate ferns. Traditionally, all of

836-559: The microphylls of clubmosses . Most ferns are leptosporangiate ferns . They produce coiled fiddleheads that uncoil and expand into fronds . The group includes about 10,560 known extant species. Ferns are defined here in the broad sense, being all of the Polypodiopsida , comprising both the leptosporangiate ( Polypodiidae ) and eusporangiate ferns , the latter group including horsetails , whisk ferns , marattioid ferns , and ophioglossoid ferns . The fern crown group , consisting of

880-458: The molecular phylogenetic era, creating four classes of ferns (Polypodiopsida). At that time they used the term Polypodiopsida sensu stricto to apply to the largest of these. Later the term Polypodiopsida sensu lato was used to refer to all four subclasses, and the large subclass renamed Polypodiidae . This is also referred to informally as the leptosporangiate ferns . The Polypodiidae contain seven orders whose phylogenic relationship

924-606: The Osmundaceae root used above may be wrong and a tree-branching artefact (all other ferns are genetically very distant from the Osmundaceae), and allowing the following classification: Todea Leptopteris subgenus Osmundastrum subgenus Claytosmunda subgenus Plenasium subgenus Osmunda A molecular dating study using Metzgar et al.'s data and a comprehensive set of rhizome and leaf fossils estimated that (sub)generic differentiation within Osmundaceae started by

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968-461: The family, which flourished during the Mesozoic , could reach the stature of trees and be termed tree ferns . The leaves are either holodimorphic, with separate fertile and sterile fronds assuming an entirely different structure, or have fertile and sterile portions of the frond very distinct in structure. Sporangia in the Osmundaceae are large, and open at a slit on the top; the annulus that drives

1012-431: The fronds are branched more than once, it can also be a combination of the pinnatifid are pinnate shapes. If the leaf blades are divided twice, the plant has bipinnate fronds, and tripinnate fronds if they branch three times, and all the way to tetra- and pentapinnate fronds. In tree ferns, the main stalk that connects the leaf to the stem (known as the stipe), often has multiple leaflets. The leafy structures that grow from

1056-434: The inclusion of Equisetaceae in the ferns, notably relating to the construction of their sperm and peculiarities of their roots. The leptosporangiate ferns are sometimes called "true ferns". This group includes most plants familiarly known as ferns. Modern research supports older ideas based on morphology that the Osmundaceae diverged early in the evolutionary history of the leptosporangiate ferns; in certain ways this family

1100-435: The largest genus, Osmunda , had traditionally been treated as three subgenera, Osmunda (3 species), Osmundastrum (2 species), and Plenasium (3–4 species). However, there was suspicion that the genus was not monophyletic . The first molecular phylogeny showed that Osmunda as traditionally circumscribed was paraphyletic and that Osmunda cinnamomea , despite its morphological similarity to Osmunda claytoniana ,

1144-467: The leptosporangiate ferns. The Marattiaceae are a primitive group of tropical ferns with large, fleshy rhizomes and are now thought to be a sibling taxon to the leptosporangiate ferns. Several other groups of species were considered fern allies: the clubmosses , spikemosses , and quillworts in Lycopodiophyta ; the whisk ferns of Psilotaceae ; and the horsetails of Equisetaceae . Since this grouping

1188-579: The leptosporangiates and eusporangiates, is estimated to have originated in the late Silurian period 423.2 million years ago, but Polypodiales , the group that makes up 80% of living fern diversity, did not appear and diversify until the Cretaceous , contemporaneous with the rise of flowering plants that came to dominate the world's flora. Ferns are not of major economic importance, but some are used for food, medicine, as biofertilizer , as ornamental plants, and for remediating contaminated soil. They have been

1232-555: The maternal gametophyte . The green , photosynthetic part of the plant is technically a megaphyll and in ferns, it is often called a frond . New leaves typically expand by the unrolling of a tight spiral called a crozier or fiddlehead into fronds . This uncurling of the leaf is termed circinate vernation . Leaves are divided into two types: sporophylls and tropophylls. Sporophylls produce spores; tropophylls do not. Fern spores are borne in sporangia which are usually clustered to form sori . The sporangia may be covered with

1276-412: The order and its families was not changed, and its placement remained the same in subsequent classifications including Chase and Reveal (2009), Christenhusz et al. (2011), and Christenhusz and Chase (2014). The find of an exceptionally well preserved Jurassic fossil intermediate between genus Osmunda (as shown above) and Osmundastrum lead to a re-analysis of Metzgar et al.'s data, which revealed that

1320-430: The rank of a fifth class, separating the whisk ferns and ophioglossoid ferns. The ferns are related to other groups as shown in the following cladogram: Lycophytes [REDACTED] Ferns [REDACTED] Gymnosperms [REDACTED] Angiosperms [REDACTED] The classification of Smith et al. in 2006 treated ferns as four classes: In addition they defined 11 orders and 37 families. That system

1364-500: The recently described Claytosmunda with the single species, Osmunda claytoniana . The following phylogram shows the relationship between the Osmundaceae genera and subtaxa, according to Metzgar et al.: Osmundastrum (= Osmunda cinnamomea ) 1 extant species Todea 2 extant species Leptopteris 6 extant species subgenus Claytosmunda (= Osmunda claytoniana ) 1 species subgenus Plenasium 4 extant species subgenus Osmunda 4 extant species The circumscription of

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1408-410: The relationship between birds and crocodiles appears distant. Although the bird family tree is rooted in the dinosaurs , there were a number of other, earlier groups, such as the pterosaurs , that branched off of the line leading to the dinosaurs after the last common ancestor of birds and crocodiles . The term sister group must thus be seen as a relative term, with the caveat that the sister group

1452-428: The same taxonomic level, terminology such as sister species or sister genera can be used. The term sister group is used in phylogenetic analysis , however, only groups identified in the analysis are labeled as "sister groups". An example is birds , whose commonly cited living sister group is the crocodiles , but that is true only when discussing extant organisms ; when other, extinct groups are considered,

1496-420: The sporangium opening is on the side. 128 to 512 spores are typically present. The spores are green, nearly round, and trilete. The spores germinate into gametophytes , which are green (photosynthetic) and grow at the surface. They are large and heart-shaped. The base chromosome number for members of the order is 22. Smith et al. (2006) carried out the first higher-level pteridophyte classification published in

1540-476: The spore producing vascular plants were informally denominated the pteridophytes , rendering the term synonymous with ferns and fern allies . This can be confusing because members of the division Pteridophyta were also denominated pteridophytes ( sensu stricto ). Traditionally, three discrete groups have been denominated ferns: two groups of eusporangiate ferns, the families Ophioglossaceae ( adder's tongues , moonworts , and grape ferns) and Marattiaceae ; and

1584-417: The spore wall and are dependent on the parent sporophyte for their nutrition. A fern gametophyte typically consists of: The lifecycle of a fern involves two stages, as in club mosses and horsetails . In stage one, the spores are produced by sporophytes in sporangia , which are clustered together in sori ( s.g. sorus ), developing on the underside of fertile fronds. In stage two, the spores germinate into

1628-490: The sterile leaves, and may have no green tissue at all, as in the Blechnaceae and Lomariopsidaceae . The anatomy of fern leaves can be anywhere from simple to highly divided, or even indeterminate (e.g. Gleicheniaceae , Lygodiaceae ). The divided forms are pinnate , where the leaf segments are completely separated from one other, or pinnatifid (partially pinnate), where the leaf segments are still partially connected. When

1672-463: The stipe are known as pinnae and are often again divided into smaller pinnules. Fern stems are often loosely called rhizomes , even though they grow underground only in some of the species. Epiphytic species and many of the terrestrial ones have above-ground creeping stolons (e.g., Polypodiaceae ), and many groups have above-ground erect semi-woody trunks (e.g., Cyatheaceae , the scaly tree ferns). These can reach up to 20 meters (66 ft) tall in

1716-504: The striking aspect of the ripe sporangia in Claytosmunda , Osmunda , Osmundastrum , and Plensium (subtribe Osmundinae). In these genera the sporangia are borne naked on non-laminar pinnules, while Todea and Leptopteris (subtribe Todinae) bear sporangia naked on laminar pinnules. Ferns in this family are larger than most other ferns. The stems of Osmundaceae contain vascular tissue arranged as an ectophloic siphonostele ; that is,

1760-498: The subject of research for their ability to remove some chemical pollutants from the atmosphere. Some fern species, such as bracken ( Pteridium aquilinum ) and water fern ( Azolla filiculoides ), are significant weeds worldwide. Some fern genera, such as Azolla , can fix nitrogen and make a significant input to the nitrogen nutrition of rice paddies . They also play certain roles in folklore. Extant ferns are herbaceous perennials and most lack woody growth. When woody growth

1804-477: The whisk ferns and ophioglossoid ferns are demonstrably a clade , and the horsetails and Marattiaceae are arguably another clade. Smith et al. (2006) carried out the first higher-level pteridophyte classification published in the molecular phylogenetic era, and considered the ferns as monilophytes, as follows: Molecular data, which remain poorly constrained for many parts of the plants' phylogeny, have been supplemented by morphological observations supporting

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1848-492: Was sister to the rest of the family. This was later confirmed by a detailed species-level phylogeny of the family by Metzgar et al. (2008) leading to the resurrection of the segregate genus Osmundastrum , by elevating it from subgenus, to contain it and render Osmunda monophyletic . Todea and Leptopteris are consistently resolved as sister groups, and Osmunda was found to contain three separate subclades corresponding to subgenera (now genera) Osmunda , Plenasium , and

1892-844: Was a consensus of a number of studies, and was further refined. The phylogenetic relationships are shown in the following cladogram (to the level of orders). This division into four major clades was then confirmed using morphology alone. Lycopodiophytes (club mosses, spike mosses, quillworts) Spermatophytes (seed plants) Equisetales (horsetails) [REDACTED] Ophioglossales (grapeferns etc.) Psilotales (whisk ferns) [REDACTED] Marattiales [REDACTED] Osmundales [REDACTED] Hymenophyllales (filmy ferns) [REDACTED] Gleicheniales [REDACTED] Schizaeales Salviniales (heterosporous) Cyatheales (tree ferns) [REDACTED] Polypodiales [REDACTED] Subsequently, Chase and Reveal considered both lycopods and ferns as subclasses of

1936-1260: Was used in a comprehensive taxonomic evaluation of Osmundales rhizome fossils, who provide a polytomous key using anatomical features of Osmundaceae rhizomes and an updated ‘evolutionary’ (non-cladistic) classification of fossil and extant Osmundales (see classification concepts for groups including extinct members ), which can be tentatively transferred into the following cladogram (monophyla in bold, polytomies reflect unresolved relationships) Bathypteris † monotypic, Late Permian Guirea † mono- or paraphyletic with 2 species, Late Permian to Middle Triassic Zhongmingella † monotypic, late Permian Changhsingian Lunea † monotypic, Early Jurassic Donwelliacaulis † monotypic, Middle Triassic Itopsidema (incl. Tiania ) † 1–2 species, ?Late Permian to Middle Triassic Anomorrhea † nomen dubium , Late Permian Thamnopteris † mono- or paraphyletic with 9 species, Late Permian Chasmatopteris † monotypic, Late Permian Palaeosmunda † 2–3 species, Late Permian to ?Late Triassic Millerocaulis p.p. † In total 29 species, Triassic to mid- Cretaceous Todea 3 species, Early Cretaceous to present Fern The ferns ( Polypodiopsida or Polypodiophyta ) are

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