Such sori probably arose by the fusion of smaller clusters of sori. (4) An arrangement of large sori that usually expand over the entire undersurface of the blade or pinna is represented by Acrostichum. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Choose from 500 different sets of ferns flashcards on Quizlet. 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 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. 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. It is found in the plains of the Punjab. Adiantum ËædiËæntÉm 1the walking fern or maidenhair fern is a genusof about 200 from BIOLOGY 111 at Sultan Idris University of Education. True indusium can be seen in Dryopteris, etc., whereas false indusium can be seen in Pteris, Adiantum, etc. 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. A widespread type of indusiumâ¦. The meristematic areaâthe region of new cell growthâthat 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. Polypodium and Phegopteris, sori round and uncovered. 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. Ferns â Polypodiaceae & Pteridaceae: Polypody & Brake Families Ferns are not flowering plants. 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. Adiantum). Adiantum is a fern that grows along moist walls and water courses. 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. ⢠Phylogeny of Adiantum (Pteridaceae) Version of Record Fig. 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. General structure The vegetative plant body is a sporophyte. Commonly, the base number is uniform for a genus or family, or it ranges around a given number. Northern maidenhair fern is a member of the Adiantaceae, a sub-family of the Pteridaceae family. Rhizome: The stem is underground rhizome. The familiar genus Osmunda, for example, has x = 22, Pteris 29, Asplenium 36, Dryopteris 41, Botrychium 45, and Pteridium 52. 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. They lack the separate male and female structures that form the basis of most flowering plants' reproductive processes. The indusium is round, shaped like a tiny umbrella and attached to the leaf from the middle. The taxonomic treatment of Adiantum raddianum has frequently changed. 1. Its fronds range from 30 to 75 cm (12 to 30 in) in length from the base of the leaf stalk to the tip. Northern maidenhair fern (Adiantum pedatum L.) is a deciduous, perennial fern native to Wisconsin.Itâs native to regions of North America, temperate East Asia and Himalayas within plant hardiness zones 3 â 8. It can be grown in a terrarium, potted, or in pockets of limestone rocks. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. This fern species is an important ornamental and more than seventy cultivars have been developed. In Adiantum, the sori are borne submarginally at the distal end on the under surface of the leaflets. 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. 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). Examples of sori and arrangements of sporangia in various species of ferns. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. The common specie of this genus is Adiantum Capillus-Veneris. When spores fall on a suitably moist, shady place, they begin the fern's reproductive cycle. The reflexed margin is known as false indusium. The Ferns Identifier for the British Isles Learn about ferns, Identify your fern specimen. 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. 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. Species with both diploid and tetraploid forms are common, especially among widespread, abundant ferns. Occurrence Adiantum is a common fern. It is a small herb consisting of stem, roots and leaves. ... 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. NOW 50% OFF! Ord.âFilices. Learn ferns with free interactive flashcards. 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. Ecology Moist lava or rock, roadside and shamba banks, heath scrub, moorland; 1650â4300 m Conservation Widespread; least concern (LC); uncommon in our area Note 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. A recent paper about the genus, Kessler & al. DukeSpace Scholarship by Duke Authors Menu Adiantum pedatum Linnaeus maidenhair fern Family: Pteridaceae . 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. When sori fuse laterally to form continuous lines, or coenosori, any indusia also tend to fuse. 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 ⦠Sori with hood-like indusia. 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). Woodwardia, sori oblong, parallel to ribs. Instead of using seeds, ferns make spores. 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. Indeed, many unrelated ferns were once classified together because of what are now believed to have been coincidental convergences in soral structure. 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. 1753. Duke University Libraries. 2. 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). Cooperative Extension, which staffs local offices in all 100 counties and with the Eastern Band of Cherokee Indians. Comparisons with leaves of other plant groups. Sporophyte. 2006, 2008).More recently, PPG I (2016) accept 53 genera and an estimated 1211 species. The false indusium results from the rolling under of the margin of the pinnule. https://www.britannica.com/science/false-indusium. 12. Indusium Indusium translucent, 0.5â0.7 mm wide, entire. indusium : The sorus may simply be tucked protectively under the leaf edge (below).. V.S. Visit the post for more. 10: 3â4, p. 62. Adiantum L., commonly known as the maidenhair ferns, belongs to the Pteridaceae, a family with c. 50 genera and 950 species (Smith & al. These are also grown for ornamental purposes. Stem is a short, thick and underground, usually unbranched horizontally growing rhizome. These are sterile hairs or scales intermixed with the sporangia, and they are, like indusia, believed to perform a protective function. false indusium : Maidenhair fern is distinctive and easy to recognize. The spores are produced in sporangia. It grows in shady places. The sporangia are often clustered into round or oblong dots (sori), and these are sometimes covered by a thin skin (indusium). Adiantum is homosporous. Study Resources. In various genera of ferns, the paraphyses have proved to be helpful sources of taxonomic data. 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. Fern Facts. Adiantum pedatum is a part of the Adiantum pedatum complex comprising of three other species, Adiantum aleuticum, Adiantum myriosorum and Adiantum viridimontanum. The genus Adiantum L. is a large and diverse group of ferns in the Old and New World trop-ics. plant. The whole plant of the Adiantum pedatum, Linné, and Adiantum capillus Veneris, Linné. It prefers to grow in moist and 8 shady habitats. Because 24 Other ferns: Davallia trichomanoides Squirrel's Foot Fern, Rabbit's Foot Fern Davalliaceae Note the prostrate rhizomes, covered with shaggy scales. 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. 1. 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. 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. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Dum to this characteristic the Adiantum is also called maidenhair fern. Navigate parenthood with the help of the Raising Curious Learners podcast. A sorus is covered by a flap-like outgrowth from its surface (true indusium, e.g. 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. Southern Maidenhair Fern is a popular horticultural species, and many varieties are available from nurseries. Paraphyses usually are hairs or modifications of hairs that arise among the sporangia or on the sporangial stalk or capsule. The base chromosome numbers (indicated by the symbol x) have been used for classification purposes. estimates c. 225 species, widely distributed from cold temperatures to tropics, most of them occurring ⦠The sori are green but become dark brown when ripe. Life Cycle. It is differentiated into stem, leaves and roots. Adiantum spp is common in plains and hilly tracts of Pakistan. 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. Notes on Taxonomy and Nomenclature Top of page. Adiantum is among the most distinctive and easily recognized leptosporangiate fern genera. 2: 1094. A widespread type of indusium⦠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. 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. 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. Note the marginal sporangia, with a false indusium . Dryopteris) or turned margin of the sporophyll (false indusium, e.g. ... and are protected by bent margin of the leaflet, forming false indusium. 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). 1. 4. The life cycle of Adiantum shows heteromorphic alternation of generation. The sporophyte is dominant and the gametophyte is small and reduced but separate and independent. Ophioglossum reticulatum has 1,440 chromosomes, the highest number of any organism known to science. These sword fern indusia do not quite reach the edge of the sori. A group of sporangia forms sori. Sporangia and especially sori have traditionally provided the most important characters for fern classification. The study of chromosomes, hybrids, and breeding systems has revealed much of value in understanding ferns. The name A. raddianum honours the Italian botanist Giuseppe Raddi (1770-1829). . 3. Leaf of Adiantum ⦠The reproduction takes place by the production of spores. Also, spores can stick together and form spore clumps. Figures Fig. Individual sporangia are easily visible around the edge of each sorus. leaflets. They are usually described as having a rachis that for⦠Vegetative reproduction occurs by fragmentation of rhizome, adventitious buds (e.g., Dryopteris), bulbils, etc. Adiantum hispidulum occurs only as an escape from cultivation. A sorus may be protected by an umbrella-like indusium, as shown below. So it forms false indusium. Hand in hand with the reduction in size of single sporangia are seen more and more complex aggregations of sporangia known as sori. 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. Adiantum is a widespread fern which grows in mild climates. Ferns overall still have relatively high levels of polyploidy, but these polyploids are all of relatively recent origin. The sporophyte produces a large number of sori (singular sorus). Deciduous. Pteris sp. Pl. 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. Britannica Kids Holiday Bundle! 3. Nat. The leaflets and leaves having sori or sporangia are called sporophylls. (3) Round and naked sori (i.e., without an indusium) are found in Polypodium. Main Menu; ... Members of the family all have intramarginal, linear sori with a flap-like indusium arising along one edge. Adiantum Linnaeus, Sp. The petioles of the leaves are shining black and brittle. One is the so-called false indusium, a rolled-over leaf margin under which sporangia form and mature. This has resulted in a number of synonyms, of which Adiantum cuneatum is still widely used. It is found on moist walls or rocky places. In some genera, marginal sori are protected by a two-lipped, or valvate, indusium (e.g., Dennstaedtia, Dicksonia, and Hymenophyllum). (2) A line of sporangia along the leaf edge, protected usually by a rolled-over and modified laminar margin, is represented by Pteris. Approximately 45 percent of the extant species of ferns are such neopolyploids. 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 âfalse indusiumâ (pseudoindusium). The sori are marginal but the reflex margins of the pinna form a protective membranous structure called false indusium (Figure 2.35). frond. 489 TAXON 67 (3) ⢠June 2018: 488â502 Huiet & al. Petris and Adiantum, sporangia covered by the edge of leaf. The shape of the frond in A. pedatum, A. aleuticum, and A. viridimontanum is very similar. Introduction. In ferns, spores are contained within cases called sporangia that are located on the underside of leaves. One is the so-called false indusium, a rolled-over leaf margin under which sporangia form and mature. Hardiness (USDA zones): 3-8 â 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 Approximately one-third of fern species have paraphyses of one type or another. 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Indusia also tend to fuse to cover sorus the Raising Curious Learners podcast, leaves and.! Shows heteromorphic alternation of generation one type or another a member of the leaflet, forming false indusium Giuseppe! The family all have intramarginal, linear sori with a flap-like indusium arising along one edge as.! In the interior of the pinnule usually expand over the entire undersurface of the Punjab,. The false indusium hand in hand with the reduction in size of single are! A member of the leaflets and leaves having sori or sporangia are easily visible around the edge each... Sporangia, and information from Encyclopaedia Britannica is covered by the fusion of smaller clusters of sori....
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