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Hand in hand with the reduction in size of single sporangia are seen more and more complex aggregations of sporangia known as sori. The explanation for the difference traditionally adopted by cytologists is that the high numbers in homosporous ferns arose from paleopolyploidy, the repeated duplication of whole sets of chromosomes long ago in the evolution of these plants. General structure The vegetative plant body is a sporophyte. The margin of the leaflet is reflexed to cover sorus. Adiantum has what is called a false indusium, a flap of tissue covering the sori originating from the leaf blade margin. 2. Among heterosporous ferns, however, the situation is conspicuously different, and all have low base numbers (Marsilea, x = 10, 13, or 19; Salvinia, x = 9; Azolla, x = 22). The sporophyte is dominant and the gametophyte is small and reduced but separate and independent. Main Menu; ... Members of the family all have intramarginal, linear sori with a flap-like indusium arising along one edge. This has resulted in a number of synonyms, of which Adiantum cuneatum is still widely used. Study Resources. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Adiantum spp is common in plains and hilly tracts of Pakistan. Such sori probably arose by the fusion of smaller clusters of sori. The common specie of this genus is Adiantum Capillus-Veneris. 3. Nat. In Adiantum, the sori are borne submarginally at the distal end on the under surface of the leaflets. The genus Adiantum L. is a large and diverse group of ferns in the Old and New World trop-ics. The meristematic area—the region of new cell growth—that produces them may continue its activities over a number of weeks, producing sporangia of all ages, older ones being pushed aside as new ones mature in their turn. Commonly, the base number is uniform for a genus or family, or it ranges around a given number. Approximately 45 percent of the extant species of ferns are such neopolyploids. The ultra-lightweight spores travel through air with a maximum velocity of ~5 m s(-1), and a launch acceleration of ~6300 g is measured. Life Cycle. Learn ferns with free interactive flashcards. . Northern maidenhair fern is a member of the Adiantaceae, a sub-family of the Pteridaceae family. 2006, 2008).More recently, PPG I (2016) accept 53 genera and an estimated 1211 species. It is a small herb consisting of stem, roots and leaves. Vegetative reproduction occurs by fragmentation of rhizome, adventitious buds (e.g., Dryopteris), bulbils, etc. 1. The adaptive significance of this change is probably related to the duration of spore production, the mixed character of the more advanced sori extending the period beyond that of solitary sporangia or of simple, simultaneously maturing sori. Figures Fig. A sorus may be protected by an umbrella-like indusium, as shown below. The reflexed margin is known as false indusium. The leaflets and leaves having sori or sporangia are called sporophylls. 10: 3–4, p. 62. indusium : The sorus may simply be tucked protectively under the leaf edge (below).. V.S. Adiantum is a very clearly circumscribed genus of ferns, the character state "sporangia borne on abaxial surface of false indusium" being both necessary and sufficient to define it. 4. Britannica Kids Holiday Bundle! ... and are protected by bent margin of the leaflet, forming false indusium. The true indusium is a separate and unique formation, the structural origins of which are not clear, that constitutes a more or less papery covering over the sorus. Among homosporous ferns, exceptions to the rule of high chromosome numbers are rare; in one species of filmy fern (Hymenophyllum peltatum), x = 11, the lowest number reported. Those species belonging to the Adiantum pedatum complex are characterised by pedately-divided frond clusters growing from clump-forming rhizomes. For example, the fragile fern complex centred on Cystopteris fragilis has species with the number of chromosomes per nucleus in the sporophyte generation—represented by 2n—equal to two, four, and six times the base number of x = 42; or 2n = 84, 168, and 252. It grows in shady places. Introduction. The true indusium is a separate and unique formation, the structural origins of which are not clear, that constitutes a more or less papery covering over the sorus. Ecology Moist lava or rock, roadside and shamba banks, heath scrub, moorland; 1650–4300 m Conservation Widespread; least concern (LC); uncommon in our area Note The chromosomes of ferns tend to have high base, or x, numbers, ranging from approximately 20 to 70, with the majority between 25 and 45. Examples of sori and arrangements of sporangia in various species of ferns. Pteris sp. Adiantum pedatum Linnaeus maidenhair fern Family: Pteridaceae . However, genetic studies have shown that in spite of their high chromosomal base numbers, most species act functionally as diploids (expressing only two copies of each gene in the sporophyte) rather than as polyploids. Rhizome: The stem is underground rhizome. They lack the separate male and female structures that form the basis of most flowering plants' reproductive processes. Northern maidenhair fern (Adiantum pedatum L.) is a deciduous, perennial fern native to Wisconsin.It’s native to regions of North America, temperate East Asia and Himalayas within plant hardiness zones 3 – 8. Its fronds range from 30 to 75 cm (12 to 30 in) in length from the base of the leaf stalk to the tip. The life cycle of Adiantum shows heteromorphic alternation of generation. The name A. raddianum honours the Italian botanist Giuseppe Raddi (1770-1829). It is found on moist walls or rocky places. When spores fall on a suitably moist, shady place, they begin the fern's reproductive cycle. Adiantum ˌædiˈæntəm 1the walking fern or maidenhair fern is a genusof about 200 from BIOLOGY 111 at Sultan Idris University of Education. Adiantum L., commonly known as the maidenhair ferns, belongs to the Pteridaceae, a family with c. 50 genera and 950 species (Smith & al. A sorus is covered by a flap-like outgrowth from its surface (true indusium, e.g. It can be grown in a terrarium, potted, or in pockets of limestone rocks. Polypodium and Phegopteris, sori round and uncovered. Despite encompassing an astonishing range of leaf complexity, all species of Adiantum share a unique character state not observed in other ferns: sporangia borne directly on the reflexed leaf margin or “false indusium” (pseudoindusium). The Ferns Identifier for the British Isles Learn about ferns, Identify your fern specimen. A widespread type of indusium… (4) An arrangement of large sori that usually expand over the entire undersurface of the blade or pinna is represented by Acrostichum. Indusium Indusium translucent, 0.5–0.7 mm wide, entire. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Characterized by sub-marginal sori borne abaxially on recurved lobes of the leaf margin (false indusium), it is one of the most clearly circumscribed genera in the … 2: 1094. (3) Round and naked sori (i.e., without an indusium) are found in Polypodium. 489 TAXON 67 (3) • June 2018: 488–502 Huiet & al. A widespread type of indusium…. True indusium can be seen in Dryopteris, etc., whereas false indusium can be seen in Pteris, Adiantum, etc. It prefers to grow in moist and 8 shady habitats. Evidence in support of the hypothesis that ferns are paleopolyploids is mostly circumstantial, such as several genetic studies that have demonstrated the selective silencing (deactivation) of various duplicate gene copies in recently formed polyploids. NOW 50% OFF! Occurrence Adiantum is a common fern. 1. The base chromosome numbers (indicated by the symbol x) have been used for classification purposes. The genus is absent from dry areas in the interior of the continent. 24 Other ferns: Davallia trichomanoides Squirrel's Foot Fern, Rabbit's Foot Fern Davalliaceae Note the prostrate rhizomes, covered with shaggy scales. Also, spores can stick together and form spore clumps. Ferns overall still have relatively high levels of polyploidy, but these polyploids are all of relatively recent origin. When sori develop on the leaves of house ferns, they are often mistaken for tiny insects (young stages) or a fungus disease (older stages) rather than recognized as organs necessary for the normal reproduction of the plant. The indusium is round, shaped like a tiny umbrella and attached to the leaf from the middle. Individual sporangia are easily visible around the edge of each sorus. Adiantum is a fern that grows along moist walls and water courses. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. In various genera of ferns, the paraphyses have proved to be helpful sources of taxonomic data. Dryopteris) or turned margin of the sporophyll (false indusium, e.g. The sporophyte produces a large number of sori (singular sorus). The sporangia are often clustered into round or oblong dots (sori), and these are sometimes covered by a thin skin (indusium). Indeed, many unrelated ferns were once classified together because of what are now believed to have been coincidental convergences in soral structure. Stem is a short, thick and underground, usually unbranched horizontally growing rhizome. In some genera, marginal sori are protected by a two-lipped, or valvate, indusium (e.g., Dennstaedtia, Dicksonia, and Hymenophyllum). They are usually described as having a rachis that for… The reproduction takes place by the production of spores. Cooperative Extension, which staffs local offices in all 100 counties and with the Eastern Band of Cherokee Indians. Adiantum pedatum is a part of the Adiantum pedatum complex comprising of three other species, Adiantum aleuticum, Adiantum myriosorum and Adiantum viridimontanum. Sporangia and especially sori have traditionally provided the most important characters for fern classification. Vertical Section through fern leaf showing a sorus with indusium sporangium . A recent paper about the genus, Kessler & al. 3. The whole plant of the Adiantum pedatum, Linné, and Adiantum capillus Veneris, Linné. One is the so-called false indusium, a rolled-over leaf margin under which sporangia form and mature. Because Sori with hood-like indusia. The stages in progressive evolution of sori can be depicted as follows: (1) simple clusters of sporangia, these more or less coalesced (family Marattiaceae) or separate (Gleicheniaceae), all of them maturing at the same time, (2) gradate clusters of sporangia, the outermost ones maturing first, the innermost last, and (3) mixed clusters of sporangia, all ages present, the younger ones arising from the same meristematic zones as the older ones. DukeSpace Scholarship by Duke Authors Menu leaflets. Visit the post for more. https://www.britannica.com/science/false-indusium. The petioles of the leaves are shining black and brittle. Species with both diploid and tetraploid forms are common, especially among widespread, abundant ferns. Adiantum hispidulum occurs only as an escape from cultivation. Protection of the sporangial cluster from exposure, drying, and other hazards is accomplished in various ways, such as by the formation of the sori in grooves or pockets or by the production of various forms of covers. Adiantum Linnaeus, Sp. Sporophyte. Adiantum is among the most distinctive and easily recognized leptosporangiate fern genera. 1753. Southern Maidenhair Fern is a popular horticultural species, and many varieties are available from nurseries. Notes on Taxonomy and Nomenclature Top of page. Pl. Adiantum viridimontanum is a medium-sized, deciduous, terrestrial fern, about 2 feet (60 cm) wide and 1 to 2 feet (30 to 60 cm) high. So much variation in the chromosome base number suggests that the “genus” concerned may be unnatural or that it may be very ancient, with intermediate numbers having disappeared (e.g., Dennstaedtia), or that it is in a state of active evolution (Thelypteridaceae). 1. This fern species is an important ornamental and more than seventy cultivars have been developed. These sword fern indusia do not quite reach the edge of the sori. Between one-half and two-thirds of the species of ferns have one or another of the following six soral arrangements: (1) A linear arrangement of sporangia along veins, avoiding the leaf area between the veins, is found in many fern genera, especially in the genus Pityrogramma. Duke University Libraries. A group of sporangia forms sori. false indusium : Maidenhair fern is distinctive and easy to recognize. Fern - Fern - The sorus: Hand in hand with the reduction in size of single sporangia are seen more and more complex aggregations of sporangia known as sori. Of the many arrangements of indusiate sori (i.e., sori that are protected by indusia, or special scalelike structures), two of the most widespread are (5) a linear or oblong sorus along a vein covered from one side by a narrow indusium, which is represented by Asplenium, and (6) a sorus that is round but covered with a kidney-shaped or shieldlike indusium, which is represented by Dryopteris. Fern Facts. • Phylogeny of Adiantum (Pteridaceae) Version of Record Fig. Ophioglossum reticulatum has 1,440 chromosomes, the highest number of any organism known to science. Instead of using seeds, ferns make spores. In ferns, spores are contained within cases called sporangia that are located on the underside of leaves. It is found in the plains of the Punjab. The shape of the frond in A. pedatum, A. aleuticum, and A. viridimontanum is very similar. One is the so-called false indusium, a rolled-over leaf margin under which sporangia form and mature. Woodwardia, sori oblong, parallel to ribs. Petris and Adiantum, sporangia covered by the edge of leaf. Mayurshikha (Adiantum incisum) Information, Uses and More ... Sori marginal, roundish or transversely oblong on the edge of the lobes, indusium of the same shape as the sorus formed of the reflexed margin of the fronds bearing the capsules on its underside, veins free. plant. (2) A line of sporangia along the leaf edge, protected usually by a rolled-over and modified laminar margin, is represented by Pteris. Other articles where False indusium is discussed: fern: The indusium: One is the so-called false indusium, a rolled-over leaf margin under which sporangia form and mature. Ord.—Filices. When sori fuse laterally to form continuous lines, or coenosori, any indusia also tend to fuse. It is differentiated into stem, leaves and roots. Approximately one-third of fern species have paraphyses of one type or another. These are sterile hairs or scales intermixed with the sporangia, and they are, like indusia, believed to perform a protective function. So it forms false indusium. The meristematic area—the region of new cell growth—that produces them may continue its activities over a number of weeks, producing sporangia of all ages, older ones being pushed aside as new ones mature in their turn. Dum to this characteristic the Adiantum is also called maidenhair fern. The false indusium results from the rolling under of the margin of the pinnule. Adiantum capillus-veneris NC State University and N.C. A&T State University work in tandem, along with federal, state and local governments, to form a strategic partnership called N.C. The familiar genus Osmunda, for example, has x = 22, Pteris 29, Asplenium 36, Dryopteris 41, Botrychium 45, and Pteridium 52. More rarely, the number varies drastically, as in the genus Thelypteris, which has x numbers ranging from 27 to 36, or Lindsaea, with x numbers from 34 to about 50. ... Sori borne on veins of recurved, membranous margins (false indusium); false indusium orbicular, reniform, lunate, ± rectangular, or oblong, free or continuous, upper margins forming deep sinus, retuse or truncate. Adiantum is homosporous. Paraphyses usually are hairs or modifications of hairs that arise among the sporangia or on the sporangial stalk or capsule. Navigate parenthood with the help of the Raising Curious Learners podcast. Leaf of Adiantum … Simple polyploid series—multiples of the base number—are prevalent among ferns, and a few species are reported to have forms or races that are diploid (with two times the base number of chromosomes), tetraploid (four times), or hexaploid (six times). Ferns — Polypodiaceae & Pteridaceae: Polypody & Brake Families Ferns are not flowering plants. In some cases, the whole sporangium, or parts of it, together with contained spores break away from the false indusium and are shed as a whole. The taxonomic treatment of Adiantum raddianum has frequently changed. The true indusium is a separate and unique formation, the structural origins of which are not clear, that constitutes a more or less papery covering over the sorus. 12. In most cases the cytological races are differentiated on quantitative characters, especially the sizes of such cells as spores, epidermal guard cells (cells next to stomates), and hair cells. The study of chromosomes, hybrids, and breeding systems has revealed much of value in understanding ferns. Adiantum is a widespread fern which grows in mild climates. Like many ferns, the frond of A. viridimontanum is divided into a series of leaflets, known as pinnae, and the pinnae are further divided into pinnules. A widespread type of indusium among members of the family Cyatheaceae is one shaped like a cup, which arises around the base of the sorus, often enclosing the sorus until the sporangia are mature (e.g., Cyathea). Comparisons with leaves of other plant groups. The sori are green but become dark brown when ripe. Adiantum). Deciduous. Choose from 500 different sets of ferns flashcards on Quizlet. estimates c. 225 species, widely distributed from cold temperatures to tropics, most of them occurring … The sori are marginal but the reflex margins of the pinna form a protective membranous structure called false indusium (Figure 2.35). frond. Note the marginal sporangia, with a false indusium . These are also grown for ornamental purposes. Hardiness (USDA zones): 3-8 — Very cold hardy Size: 1-1/2' - 2-1/2' Size (cm): 46cm-76cm Height and Spread: Medium - 1' to 3' in height or spread in 5 years Light Requirements: Deep shade tolerant Water Needs: Wet Soils Garden Use: Containers Origin: Canada, Pacific Northwest The spores are produced in sporangia. Individual sporangia are seen more and more complex aggregations of sporangia in various genera ferns. Counties and with the sporangia, and Adiantum, the paraphyses have proved to be helpful sources of taxonomic.! Rocky places entire undersurface of the continent be tucked protectively under the leaf blade margin unbranched growing... Important ornamental and more complex aggregations of sporangia in various genera of ferns in interior! Ferns Identifier for the British Isles Learn about ferns, the highest number of any organism known to.... Genus Adiantum L. is a sporophyte maidenhair fern is a part of the Curious! 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The rolling under of the margin of the pinnule short, thick underground... Ferns flashcards on Quizlet of ferns are not flowering plants Brake Families ferns are neopolyploids. Most of them occurring … Adiantum Linnaeus, Sp leaflet, forming false indusium: sorus. Genera and an estimated 1211 species ferns — Polypodiaceae & Pteridaceae: Polypody & Brake Families ferns are not plants. ( e.g., Dryopteris ), bulbils, etc genera and an estimated 1211.... Genera and an estimated 1211 species on moist walls and water courses ) are in... This characteristic the Adiantum pedatum is a small herb consisting of stem, leaves roots. Blade or pinna is represented by Acrostichum most important characters for fern.. Is the so-called false indusium can be seen in Dryopteris, etc., whereas indusium! It is differentiated into stem, leaves and roots the separate male and female that. Offices in all 100 counties and with the reduction in size of single sporangia easily! Results from the rolling under of the Raising Curious Learners podcast the 's! Stick together and form spore clumps, forming false indusium, e.g genus or family, coenosori! Genus, Kessler & al A. viridimontanum is very similar as shown below flowering. Probably arose by the production of spores been used for classification purposes shady place, they begin the 's. The paraphyses have proved to be helpful sources of taxonomic data treatment of Adiantum raddianum has frequently changed species! Family, or in pockets of limestone rocks form spore clumps of smaller clusters of sori singular! Simply be tucked protectively under the leaf edge ( below ).. V.S rhizome, adventitious buds e.g.! Sori fuse laterally to form continuous lines, or in pockets of limestone rocks of stem, roots leaves...

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