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52-643: 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 (PPG I). 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

104-436: A polysaccharide called callose . Other parenchyma cells within the phloem are generally undifferentiated and used for food storage. The metabolic functioning of sieve-tube members depends on a close association with the companion cells , a specialized form of parenchyma cell. All of the cellular functions of a sieve-tube element are carried out by the (much smaller) companion cell, a typical nucleate plant cell except

156-465: A basal sister clade to the rest of the family. This family has been determined by genetic analysis to be closely allied to the Blechnaceae , within the clade of families sometimes known as Blechnales (which includes the athyrioid ferns and asplenioid ferns as well) (this clade is often treated as part of the order Polypodiales however). Matteuccia struthiopteris was previously classified under

208-734: 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

260-634: 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

312-405: 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

364-461: A gutter-shape. The blades are pinnatifid or pinnate-pinnatifid. The veins are free or anastomosing, lacking included veinlets. The spores are reniform , brownish to green. The sori are enclosed (sometimes tightly) by reflexed laminar margins, also with membranous, often fugacious true indusia. Formerly, the two species in the genus Pentarhizidium were considered to be members of Matteuccia , but genetic analysis has determined that they compose

416-487: 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

468-1046: 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 Phloem Phloem tissue consists of conducting cells , generally called sieve elements, parenchyma cells, including both specialized companion cells or albuminous cells and unspecialized cells and supportive cells, such as fibres and sclereids . Sieve tube elements are

520-429: A process called phloem loading and unloading . Phloem sap is also thought to play a role in sending informational signals throughout vascular plants. "Loading and unloading patterns are largely determined by the conductivity and number of plasmodesmata and the position-dependent function of solute -specific, plasma membrane transport proteins . Recent evidence indicates that mobile proteins and RNA are part of

572-462: 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

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624-430: 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

676-568: 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

728-402: A total of five species, are accepted. A molecular phylogenetic analysis in 2011 suggested that the four Onocleacae genera are so closely related that they could be included under the single genus Onoclea . A possible phylogenic relationship between Onocleaceae species (line lengths are not significant) is shown below. The Pteridophyte Phylogeny Group classification of 2016 (PPG I) maintained

780-500: 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,

832-416: Is composed primarily of dead cells), the phloem is composed of still-living cells that transport sap . The sap is a water-based solution, but rich in sugars made by photosynthesis. These sugars are transported to non-photosynthetic parts of the plant, such as the roots, or into storage structures, such as tubers or bulbs. During the plant's growth period, usually during the spring, storage organs such as

884-578: 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

936-419: Is laid down by the vascular cambium to the inside of the established layer(s) of phloem. The molecular control of phloem development from stem cell to mature sieve element is best understood for the primary root of the model plant Arabidopsis thaliana . In some eudicot families ( Apocynaceae , Convolvulaceae , Cucurbitaceae , Solanaceae , Myrtaceae , Asteraceae , Thymelaeaceae ), phloem also develops on

988-435: Is little to impede the movement of fluids. One of the few organelles they do contain at maturity is the rough endoplasmic reticulum , which can be found at the plasma membrane, often nearby the plasmodesmata that connect them to their companion or albuminous cells. All sieve cells have groups of pores at their ends that grow from modified and enlarged plasmodesmata, called sieve areas . The pores are reinforced by platelets of

1040-613: 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

1092-527: Is transport of sugars, phloem may also contain cells that have a mechanical support function. These are sclerenchyma cells which generally fall into two categories: fibres and sclereids. Both cell types have a secondary cell wall and are dead at maturity. The secondary cell wall increases their rigidity and tensile strength, especially because they contain lignin . Bast fibres are the long, narrow supportive cells that provide tension strength without limiting flexibility. They are also found in xylem , and are

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1144-670: The Dryopteridaceae , and still is by the USDA . The following cladogram for the suborder Aspleniineae (as eupolypods II), based on Lehtonen (2011), and Rothfels & al. (2012), shows a likely phylogenetic relationship between the Onocleaceae and the other families of the clade. Cystopteridaceae Rhachidosoraceae Diplaziopsidaceae Aspleniaceae Hemidictyaceae Thelypteridaceae Woodsiaceae Onocleaceae Blechnaceae Athyriaceae Four genera, with

1196-479: 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

1248-566: 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

1300-423: The roots are sugar sources, and the plant's many growing areas are sugar sinks. The movement in phloem is multidirectional, whereas, in xylem cells, it is unidirectional (upward). After the growth period, when the meristems are dormant, the leaves are sources, and storage organs are sinks. Developing seed -bearing organs (such as fruit ) are always sinks. Because of this multi-directional flow, coupled with

1352-436: The bark at a fairly precise height. This process is known as girdling, or ring-barking, and can be used for agricultural purposes. For example, enormous fruits and vegetables seen at fairs and carnivals are produced via girdling. A farmer would place a girdle at the base of a large branch, and remove all but one fruit/vegetable from that branch. Thus, all the sugars manufactured by leaves on that branch have no sinks to go to but

1404-534: The companion cell usually has a larger number of ribosomes and mitochondria . The dense cytoplasm of a companion cell is connected to the sieve-tube element by plasmodesmata. The common sidewall shared by a sieve tube element and a companion cell has large numbers of plasmodesmata. There are three types of companion cells. Albuminous cells have a similar role to companion cells, but are associated with sieve cells only and are hence found only in seedless vascular plants and gymnosperms . Although its primary function

1456-413: The fact that sap cannot move with ease between adjacent sieve-tubes, it is not unusual for sap in adjacent sieve-tubes to be flowing in opposite directions. While movement of water and minerals through the xylem is driven by negative pressures (tension) most of the time, movement through the phloem is driven by positive hydrostatic pressures . This process is termed translocation , and is accomplished by

1508-401: The four genera. Matteuccia struthiopteris (or Onoclea struthiopteris ) Onocleopsis hintonii (or Onoclea hintonii ) Onoclea sensibilis var interrupta Onoclea sensibilis var sensibilis Pentarhizidium orientale (or Onoclea orientalis ) Pentarhizidium intermedium (or Onoclea intermedia ) Fern The ferns ( Polypodiopsida or Polypodiophyta ) are

1560-431: 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

1612-494: 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

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1664-440: The inner side of the vascular cambium; in this case, a distinction between external and internal or intraxylary phloem is made. Internal phloem is mostly primary, and begins differentiation later than the external phloem and protoxylem, though it is not without exceptions. In some other families ( Amaranthaceae , Nyctaginaceae , Salvadoraceae ), the cambium also periodically forms inward strands or layers of phloem, embedded in

1716-474: 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

1768-585: 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

1820-432: The main component of many textiles such as paper, linen, and cotton. Sclereids are irregularly shaped cells that add compression strength but may reduce flexibility to some extent. They also serve as anti-herbivory structures, as their irregular shape and hardness will increase wear on teeth as the herbivores chew. For example, they are responsible for the gritty texture in pears, and in winter pears. Unlike xylem (which

1872-555: 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

1924-408: The one fruit/vegetable, which thus expands to many times its normal size. When the plant is an embryo, vascular tissue emerges from procambium tissue, which is at the center of the embryo. Protophloem itself appears in the mid-vein extending into the cotyledonary node, which constitutes the first appearance of a leaf in angiosperms, where it forms continuous strands. The hormone auxin , transported by

1976-411: The order Diptera, including the fruit fly Drosophila montana . Because phloem tubes are located outside the xylem in most plants, a tree or other plant can be killed by stripping away the bark in a ring on the trunk or stem. With the phloem destroyed, nutrients cannot reach the roots, and the tree/plant will die. Trees located in areas with animals such as beavers are vulnerable since beavers chew off

2028-432: The plant's long-distance communication signaling system. Evidence also exists for the directed transport and sorting of macromolecules as they pass through plasmodesmata." Organic molecules such as sugars, amino acids , certain phytohormones , and even messenger RNAs are transported in the phloem through sieve tube elements. Phloem is also used as a popular site for oviposition and breeding of insects belonging to

2080-426: The plants to produce the sieve elements. In the embryo, root phloem develops independently in the upper hypocotyl, which lies between the embryonic root, and the cotyledon. In an adult, the phloem originates, and grows outwards from, meristematic cells in the vascular cambium . Phloem is produced in phases. Primary phloem is laid down by the apical meristem and develops from the procambium . Secondary phloem

2132-459: The protein PIN1 is responsible for the growth of those protophloem strands, signaling the final identity of those tissues. SHORTROOT (SHR), and microRNA165 / 166 also participate in that process, while Callose Synthase 3 inhibits the locations where SHR, and microRNA165 can go. Additionally, the expression of NAC45/86 genes during phloem differentiation functions to enucleate specific cells in

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2184-430: 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

2236-425: The single genus Onoclea . Members of the family have the following characteristics, being distinguished by having strongly dimorphic fronds , with the fertile fronds different from the sterile fronds. The rhizomes are long- to short-creeping to ascending, and sometimes stoloniferous ( Matteuccia and Onocleopsis ). The leaves are strongly dimorphic and the petioles have two vascular bundles uniting distally into

2288-476: 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

2340-417: 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

2392-437: 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

2444-463: 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

2496-498: 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

2548-429: The type of cell that are responsible for transporting sugars throughout the plant. At maturity they lack a nucleus and have very few organelles , so they rely on companion cells or albuminous cells for most of their metabolic needs. Sieve tube cells do contain vacuoles and other organelles, such as ribosomes , before they mature, but these generally migrate to the cell wall and dissolve at maturity; this ensures there

2600-477: 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

2652-566: The xylem: Such phloem strands are called included or interxylary phloem. Phloem of pine trees has been used in Finland and Scandinavia as a substitute food in times of famine and even in good years in the northeast. Supplies of phloem from previous years helped stave off starvation in the great famine of the 1860s which hit both Finland and Sweden . Phloem is dried and milled to flour ( pettu in Finnish ) and mixed with rye to form

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2704-844: 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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