48-582: The Lomariopsidaceae is a family of ferns with a largely tropical distribution. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the family is placed in the suborder Polypodiineae (eupolypods I) of the order Polypodiales . Alternatively, it may be treated as the subfamily Lomariopsidoideae of a very broadly defined family Polypodiaceae sensu lato . The Pteridophyte Phylogeny Group classification of 2016 (PPG I) included four genera. Dryopolystichum
96-734: 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
144-634: 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
192-652: A foodstuff for human consumption, however, no long-term studies of the safety of eating Azolla have been made on humans. Previous studies attributed neurotoxin production to Anabaena flos-aquae species, which is also a type of nitrogen-fixing cyanobacteria. Studies published in 2024 have found that “the Azolla–Nostoc azollae superorganism does not contain BMAA or their isomers DAB and AEG and that Azolla and N. azollae do not synthesize other common cyanotoxins”. Further research may be needed to ascertain whether A. azollae
240-574: A hot, tropical environment. This research was conducted by the Institute of Environmental Biology at Utrecht University . It indicates that massive patches of Azolla growing on the (then) freshwater surface of the Arctic Ocean consumed enough carbon dioxide from the atmosphere for the global greenhouse effect to decline, eventually causing the formation of ice sheets in Antarctica and
288-487: 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
336-844: 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 Azolla See text Azolla ( mosquito fern , water fern , fairy moss )
384-462: 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
432-469: A reduction in the proportion of polyunsaturated fatty acids in the fronds , thus lowering their palatability and nutritive value. Azolla cannot survive winters with prolonged freezing, so is often grown as an ornamental plant at high latitudes where it cannot establish itself firmly enough to become a weed. It is also not tolerant of salinity ; normal plants cannot survive in greater than 1–1.6‰, and even conditioned organisms die if grown in water with
480-681: A salinity above 5.5‰. Azolla filiculoides (red azolla) is the only member of this genus and of the family Azollaceae in Tasmania . It is a common native aquatic plant in Tasmania . It is common behind farm dams and other still waterbodies. The plants are small (usually only a few cm across) and float, but they are fast growing, and can be abundant and form large mats. The plants are typically red, and have small, water repellent leaves. Azolla reproduces sexually, and asexually (by splitting). Like all ferns, sexual reproduction leads to spore formation, but unlike other members of this group Azolla
528-430: 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
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#1732797649380576-812: 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
624-568: 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
672-472: A thick mat on the surface of the water, making it more difficult for the larvae to reach the surface to breathe, effectively choking the larvae. Azolla has been proposed as a carbon sequestration modality. The proposal draws upon the hypothesized Azolla event that asserts that Azolla once covered the Arctic and then sank, permanently sequestering teratons of carbon that would otherwise have contributed to
720-528: A tropical biomass agricultural system, reducing the need for food supplements. Concerns about biomagnification exist because the plant may contain the neurotoxin BMAA that remains present in the bodies of animals consuming it and BMAA has been documented as passing along the food chain . Azolla may contain this substance that is a possible cause of neurodegenerative diseases, including causing ALS, Alzheimer's, and Parkinson's. Azolla has been suggested as
768-604: Is heterosporous , producing spores of two kinds. During the summer months, numerous spherical structures called sporocarps form on the undersides of the branches. The male sporocarp is greenish or reddish and looks like the egg mass of an insect or spider. It is two millimeters in diameter, and bears numerous male sporangia . Male spores (microspores) are extremely small and are produced inside each microsporangium . Microspores tend to adhere in clumps called massulae. Female sporocarps are much smaller, containing one sporangium and one functional spore. Since an individual female spore
816-500: 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,
864-405: Is a genus of seven species of aquatic ferns in the family Salviniaceae . They are extremely reduced in form and specialized, looking nothing like other typical ferns but more resembling the form of some mosses or even duckweeds . Azolla filiculoides is one of just two fern species for which a reference genome has been published. It is believed that this genus grew so prolifically during
912-404: Is a stub . You can help Misplaced Pages by expanding it . 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
960-526: Is a healthy foodstuff for humans. Azolla has been used for at least one thousand years in rice paddies as a companion plant , to fix nitrogen and to block out light to prevent competition from other plants. Rice is planted when tall enough to poke through the Azolla layer. Mats of mature Azolla can also be used as a weed-suppressing mulch . Rice farmers used Azolla as a rice biofertilizer 1500 years ago. The earliest known written record of this practice
1008-435: Is considerably larger than a male spore, it is termed a megaspore . Azolla has microscopic male and female gametophytes that develop inside the male and female spores . The female gametophyte protrudes from the megaspore and bears a small number of archegonia , each containing a single egg. The microspore forms a male gametophyte with a single antheridium which produces eight swimming sperm. The barbed glochidia on
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#17327976493801056-635: Is in a book written by Jia Ssu Hsieh (Jia Si Xue) in 540 AD on The Art of Feeding the People (Chih Min Tao Shu). By the end of the Ming dynasty in the early 17th century, Azolla 's use as a green compost was documented in local records. The myth that no mosquito can penetrate the coating of fern to lay its eggs in the water gives the plant its common name "mosquito fern". Azolla have been used to control mosquito larvae in rice fields. The plant grows in
1104-578: 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
1152-646: 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
1200-479: 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
1248-588: The fossil record : Azolla is a highly productive plant . It can double its biomass in as little as 1.9 days, depending on growing conditions, and yield can reach 8–10 tonnes fresh matter/ha in Asian rice fields. 37.8 t fresh weight/ha (2.78 t/ha dry weight) has been reported for Azolla pinnata in India (Hasan et al., 2009). Azolla floats on the surface of water by means of numerous small, closely overlapping scale-like leaves , with their roots hanging in
1296-487: The water . They form a symbiotic relationship with the cyanobacterium Anabaena azollae , an extracellular endosymbiont (living outside the host's cells) which fixes atmospheric nitrogen . The typical limiting factor on its growth is phosphorus ; thus, an abundance of phosphorus—due for example to eutrophication or chemical runoff—often leads to Azolla blooms. Unlike all other known plants, its symbiotic microorganism transfers directly from one generation to
1344-810: The Eocene (and thus absorbed such a large amount of carbon) that it triggered a global cooling event that has lasted to the present. Azolla may establish as an invasive plant in areas where it is not native . In such a situation it can alter aquatic ecosystems and biodiversity substantially. Phylogeny of Azolla A. nilotica Decne. ex Mett. (Nile Azolla) A. filiculoides Lam. (Large mosquito fern) A. rubra R.Br. A. caroliniana Willdenow 1810 (Eastern/Carolinian mosquito fern) Azolla cristata Kaulf. (Mexican mosquito fern) A. pinnata R.Br. (Ferny/Pacific Azolla; Feathered mosquitofern) Other species include: At least six extinct species are known from
1392-485: 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
1440-455: The coating of fern to lay its eggs in the water gives the plant its common name "mosquito fern", and may deter the survival of some of the larvae. Most species can produce large amounts of deoxyanthocyanins in response to various stresses, including bright sunlight and extreme temperatures, causing the water surface to appear to be covered with an intensely red carpet. Herbivore feeding induces accumulation of deoxyanthocyanins and leads to
1488-422: The colder climate. It can form mats up to 30 centimetres (12 in) thick and cover 100% of a water surface, preventing local insects and amphibians from reaching the surface. A study of Arctic paleoclimatology reported that Azolla may have had a significant role in reversing an increase in greenhouse effect that occurred 55 million years ago that had caused the region around the north pole to turn into
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1536-431: 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
1584-494: 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
1632-446: 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
1680-474: 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
1728-620: The male spore clusters cause them to cling to the female megaspores, thus facilitating fertilization. In addition to its traditional cultivation as a bio-fertilizer for wetland paddies, Azolla is finding increasing use for sustainable production of livestock feed . Azolla is rich in protein, essential amino acids, vitamins, and minerals. Studies describe feeding Azolla to dairy cattle , pigs, ducks, and chickens, with reported increases in milk production , weight of broiler chickens and egg production of layers, as compared to conventional feed. One FAO study describes how Azolla integrates into
1776-555: 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
1824-533: The next. A. azollae is completely dependent on its host, as several of its genes have either been lost or transferred to the nucleus in Azolla's cells. The nitrogen-fixing capability of Azolla has led to widespread use as a biofertiliser , especially in parts of southeast Asia . The plant has been used to bolster agricultural productivity in China for over a thousand years. When rice paddies are flooded in
1872-475: The planet's greenhouse effect and ending a warming event that reached 12–15 °C (22–27 °F) degrees warmer than twenty-first century averages. They contribute significantly to decreasing the atmospheric CO 2 levels. This fern has been introduced to other parts of the world, including the United Kingdom , where it has become a pest in some areas. A nominally tropical plant, it has adapted to
1920-430: 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
1968-476: 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
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2016-417: 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
2064-437: The spring, they can be planted with Azolla , which then quickly multiplies to cover the water, suppressing weeds. The rotting plant material resulting from the die off of this Azolla releases nitrogen into the water for the rice plants, providing up to nine tonnes of protein per hectare per year. Azolla are weeds in many parts of the world, entirely covering some bodies of water. The myth that no mosquito can penetrate
2112-496: 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
2160-463: 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
2208-477: 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
2256-844: 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
2304-758: Was added in 2017, and Thysanosoria is now included in Lomariopsis , so that four genera are recognized as of February 2020: The genus Nephrolepis has also been placed in this family, but it is now placed in its own family, Nephrolepidaceae . Some members of the Lomariopsidaceae are cultivated as ornamental plants . Didymochlaenaceae Hypodematiaceae Dryopteridaceae Nephrolepidaceae Lomariopsidaceae Tectariaceae Oleandraceae Davalliaceae Polypodiaceae Dryopolystichum Cyclopeltis Dracoglossum Lomariopsis This Polypodiales -related article
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