Psilophytopsida is a now obsolete class containing one order , Psilophytales , which was previously used to classify a number of extinct plants which are now placed elsewhere. The class was established in 1917, under the name Psilophyta , with only three genera ( Rhynia , Horneophyton and Psilophyton ) for a group of fossil plants from the Upper Silurian and Devonian periods which lack true roots and leaves , but have a vascular system within a branching cylindrical stem. The living Psilotaceae , the whisk-ferns, were sometimes added to the class, which was then usually called Psilopsida. This classification is no longer in use.
16-761: The class should not be confused with the current use of the name Psilotopsida , which refers to a class of living ferns, containing only Psilotaceae (whisk-ferns) and Ophioglossaceae (moon-worts and adder's-tongue ferns). The class was created in 1917 by Kidston and Lang for fossils found in the Rhynie Chert Bed . Three genera were initially included, Rhynia , Horneophyton and Psilophyton . All lacked leaves and true roots, consisting only of branched stems; however they were considered to contain vascular tissue . Additional fossil genera were added later. As described by Sporne in 1966, Psilophytopsida consisted of four families: By 1975, it had become clear that
32-693: A whole genome duplication . Later classifications renamed the group Polypodiidae, initially as a subclass of Equisetopsida sensu lato . This subclass comprises leptosporangiate ferns as opposed to the remaining three subclasses which are informally referred to as eusporangiate ferns . The following diagram shows a likely phylogenic relationship between subclass Polypodiidae and the other Equisetopsida subclasses in that system Marchantiidae Bryidae Anthocerotidae Lycopodiidae Equisetidae Marattiidae Ophioglossidae Polypodiidae Cycadidae Ginkgoidae Gnetidae Pinidae Magnoliidae In 2014, Christenhusz and Chase grouped all
48-663: A different rank. Older names for the group include Filicidae and Filicales , although at least the "water ferns" (now the Salviniales ) were then treated separately. The leptosporangiate ferns are one of the four major groups of ferns, with the other three being the eusporangiate ferns comprising the marattioid ferns (Marattiidae, Marattiaceae ), the horsetails (Equisetiidae, Equisetaceae ), and whisk ferns and moonworts . There are approximately 8465 species of living leptosporangiate ferns, compared with about 2070 for all other ferns, totalling 10535 species of ferns. Almost
64-697: A much broader grouping, the class Equisetopsida sensu lato . Christenhusz et al. , 2011, included both the Ophioglossales and Psilotales orders in the Ophioglossidae subclass. This was continued by both Christenhusz and Chase (2014) and by the Pteridophyte Phylogeny Group (2016). Under the latter the subclass is one of four subclasses of Polypodiopsida (ferns) and contains two orders, two families, 12 genera, and an estimated 129 species. The relationships between
80-453: A ring or cup around the sorus, or can also be strongly reduced to completely absent. Many leptosporangiate ferns have an annulus around the sporangium, which ejects the spores. The leptosporangiate ferns were first recognized as a group, the "Leptosporangiateen", by Karl Ritter von Goebel in 1881, who placed the eusporangiate ferns with seed plants and vascular plants into a coeval "Eusporangiateen". As this classification artificially split
96-418: A third of leptosporangiate fern species are epiphytes . These ferns are called leptosporangiate because their sporangia arise from a single epidermal cell and not from a group of cells as in eusporangiate ferns (a polyphyletic lineage). The mature sporangia have a wall that is just a single cell thick, and are typically covered with a scale called the indusium , which can cover the whole sorus , forming
112-450: Is a stub . You can help Misplaced Pages by expanding it . Polypodiidae (plant) 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
128-757: Is shown as a sister group of Marattiidae. Equisetidae Ophioglossidae Marattiidae Polypodiidae In both the Christenhusz and Chase, and the PPG classification, the extant Polypodiidae are divided into seven orders, 44 families, 300 genera, and an estimated 10,323 species. Osmundales 1 family Hymenophyllales 1 family Gleicheniales 3 families Schizaeales 3 families Salviniales 2 families Cyatheales 8 families Polypodiales 6 suborders, 26 families Osmundales Hymenophyllales Gleicheniales Schizaeales Salviniales Cyatheales Polypodiales The following phylogram shows
144-524: The sporophyte . The following cladogram shows a likely phylogenic relationship between subclass Ophioglossidae and the other Polypodiopsida subclasses. The first three small subclasses are sometimes informally referred to as eusporangiate ferns , in contrast to the largest subclass, Polypodiidae or leptosporangiate ferns . Equisetidae Ophioglossidae Marattiidae Polypodiidae The two orders, Ophioglossales and Psilotales are sister groups to each other. This fern -related article
160-593: The class had become increasingly unnatural, containing unrelated early vascular plants. It was split up by Banks into three subdivisions: Rhyniophytina, Zosterophyllophytina, and Trimerophytina. Later cladistic analyses of early land plants suggested that at least the rhyniophytes and the trimerophytes were not monophyletic . Separating out 'basal groups', such as the earliest land plants, is intrinsically difficult, since at this stage they contain many shared characters ( plesiomorphies ) which are not sufficient to distinguish them. The current classification of former members of
176-462: The class is largely due to Kenrick and Crane in 1997. Psilotopsida 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
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#1732800880892192-497: The fern subclasses together as Polypodiophyta and in 2016 the Pteridophyte Phylogeny Group (PPG) adopted the class Polypodiopsida sensu lato for the four fern subclasses. The following cladogram shows the phylogenic relationship between the subclasses according to the PPG. The first three small subclasses being informally grouped as eusporangiate ferns , in contrast to the Polypodiidae or leptosporangiate ferns. Polypodiidae
208-439: The ferns, Christian Luerssen subdivided the homosporous ferns only into Eusporangiatae and Leptosporangiatae in 1884–9. The latter group was treated at a variety of ranks in subsequent systems of classification. The subclass "Polypodiidae" was first published and used for the homosporous leptosporangiate ferns by Cronquist, Takhtajan and Zimmermann in 1966, typified on Polypodium L. . Other contemporary classifications used
224-604: The name "Filicidae" for this subclass. Smith et al. (2006) carried out the first higher-level classification of ferns based on molecular phylogenetics . They included heterosporous water ferns ( Salviniales ) (placed in a separate subclass by Cronquist et al. due to their highly modified morphology) within the leptosporangiate ferns, which they elevated to the rank of class as the Polypodiopsida (published by Cronquist et al. to include all ferns). The common ancestor of Salviniales, Cyatheales and Polypodiales went through
240-418: The two orders, Psilotales and Ophioglossales, has long been unclear and was only confirmed by molecular systematic studies. Psilotales have rhizomes instead of real roots, and the roots of Ophioglossales lack both branching and root hairs . The gametophytes of both orders are heterotrophic and often subterranean, obtaining nutrients from mycorrhiza instead of light. Photosynthesis happens exclusively in
256-500: Was only confirmed by molecular phylogenetic studies. Smith et al. (2006) carried out the first higher-level pteridophyte classification published in the molecular phylogenetic era, and considered the ferns (monilophytes), with four classes . They placed the whisk ferns and related taxa in the class Psilotopsida, with two orders . Mark W. Chase and James L. Reveal (2009) classified them as two separate subclasses, Psilotidae and Ophioglossidae, corresponding to those orders within
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