37-552: See text . Ophioglossaceae , the adder's-tongue family, is a small family of ferns . In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), it is the only family in the order Ophioglossales , which together with the Psilotales is placed in the subclass Ophioglossidae . The Ophioglossidae are one of the groups traditionally known as eusporangiate ferns . Members of the family differ from other ferns in
74-734: 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
111-478: A few members of Botrychium that are unique among ferns in having the sporophytes also mycoheterotrophic, producing only small, ephemeral sporophylls that do not photosynthesize. The plants have short-lived spores formed in sporangia lacking an annulus , and borne on a stalk that splits from the leaf blade; and fleshy roots . A few species send up fertile spikes only, without any conventional leaf-blade. The spores will not germinate if exposed to sunlight, and
148-628: 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
185-480: A member of subclass Ophioglossidae, equivalent to Smith's Psilotopsida. This approach has subsequently been followed in the classifications of Christenhusz and Chase (2014) and PPG I (2016). Older treatments recognized segregate families within the Ophioglossales, such as Botrychiaceae for the moonworts and grape ferns and Helminthostachyaceae for Helminthostachys , but modern treatments combine all members of
222-483: 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
259-788: 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 Ophioglossum See text Ophioglossum ,
296-418: A number of ways. Many have only a single fleshy leaf at a time. Their gametophytes are subterranean and rely on fungi for energy. Members of Ophioglossaceae are usually terrestrial (excepting a few epiphytic species of Ophioglossum ) and occur in both temperate and tropical areas. They differ from the other ferns in several respects: In addition to having mycoheterotrophic gametophytes, there are
333-462: 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
370-430: 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
407-812: 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 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
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#1733085608418444-568: 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
481-493: 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,
518-578: 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
555-617: Is not always a spore stalk present, and the plants do not always send up a leaf, sometimes going for a year to a period of years living only under the soil, nourished by association with soil fungi . The plant grows from a central, budding, fleshy structure with fleshy, radiating roots. Ophioglossum malviae is known as the world's smallest terrestrial fern. Ophioglossum has a high chromosome count in comparison to other species , with 120 or up to 720 chromosomes possible in intervals of 120 due to polyploidy (multiple possible copies of chromosomes). It has almost 1260 number of chromosomes in
592-640: 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 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
629-500: The Psilotales , and both are placed in the class Ophioglossidae . In the molecular phylogenetic classification of Smith et al. in 2006, Ophioglossales, in its present circumscription, was placed in the class Psilotopsida, along with the order Psilotales. The linear sequence of Christenhusz et al. (2011), intended for compatibility with the classification of Chase and Reveal (2009), which placed all land plants in Equisetopsida, made it
666-512: The adder's-tongue ferns , is a genus of about 50 species of ferns in the family Ophioglossaceae . The name Ophioglossum comes from the Greek meaning "snake-tongue". Their cosmopolitan distribution is mainly in tropical and subtropical habitats . The genus has the largest number of chromosomes in the known plant kingdom, but contrary to popular belief does not have the largest number of chromosomes out of all known organisms, falling short to
703-472: 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
740-531: The Western Ghats in India has been characterized as the world's smallest terrestrial pteridophyte with plants typically 1–1.2 cm in size. The ferns in this group were originally treated as a family and later as the separate order Ophioglossales. In some classifications, they were placed in a separate division, Ophioglossophyta, but molecular phylogenetic studies have shown the Ophioglossales to be closely related to
777-478: The branched sporophyte is the dominant phase. Ferns have complex leaves called megaphylls that are more complex than 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
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#1733085608418814-629: The family is divided has varied. The Smith system of 2006 used four genera, treating Botrychium and Ophioglossum broadly. Cheiroglossa has been segregated from Ophioglossum , or included within it. The PPG I system of 2016 divides the family into four subfamilies: Fern The ferns ( Polypodiopsida or Polypodiophyta ) are 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
851-431: 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
888-457: The gametophyte can live some two decades without forming a sporophyte . The genus Ophioglossum has the highest chromosome counts of any known plant. The record holder is Ophioglossum reticulatum , with about 630 pairs of chromosomes (1260 chromosomes per cell). Other measurements have indicated a chromosome number up to 1440 (n = 720). For comparison, humans have 46 chromosomes, consisting of n = 23 pairs . Ophioglossum malviae from
925-488: 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
962-446: The leptosporangiate ( Polypodiidae ) and eusporangiate ferns , the latter group including horsetails , whisk ferns , marattioid ferns , and ophioglossoid ferns . The fern crown group , consisting of 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
999-467: 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
1036-555: 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
1073-516: The order into the single family Ophioglossaceae. Mankyua Cheiroglossa Ophioderma Ophioglossum Helminthostachys Sahashia Botrypus Japanobotrychum Sceptridium Botrychium Mankyua Cheiroglossa Ophioderma Whittieria Goswamia Haukia Ophioglossum s.s. Helminthostachys Sahashia Botrypus Sceptridium rugulosum Japanobotrychum Sceptridium Botrychium The number of genera into which
1110-412: The protist Sterkiella histriomuscorum . Adders-tongues are so-called because the spore -bearing stalk is thought to resemble a snake's tongue. Each plant typically sends up a small, undivided leaf blade with netted venation, and the spore stalk forks from the leaf stalk, terminating in sporangia which are partially concealed within a structure with slit sides. When the leaf blade is present, there
1147-430: 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
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1184-476: 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
1221-417: 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
1258-490: 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
1295-463: 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
1332-477: 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
1369-844: 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
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