The margin of the leaflet is reflexed to cover sorus. Pteris sp. ... 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 ˌædiˈæntəm 1the walking fern or maidenhair fern is a genusof about 200 from BIOLOGY 111 at Sultan Idris University of Education. Figures Fig. 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. https://www.britannica.com/science/false-indusium. Note the marginal sporangia, with a false indusium . (4) An arrangement of large sori that usually expand over the entire undersurface of the blade or pinna is represented by Acrostichum. The Ferns Identifier for the British Isles Learn about ferns, Identify your fern specimen. Cooperative Extension, which staffs local offices in all 100 counties and with the Eastern Band of Cherokee Indians. 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. Approximately one-third of fern species have paraphyses of one type or another. 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). These sword fern indusia do not quite reach the edge of the sori. 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 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. 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. Instead of using seeds, ferns make spores. The reproduction takes place by the production of spores. 2. The indusium is round, shaped like a tiny umbrella and attached to the leaf from the middle. Adiantum is a fern that grows along moist walls and water courses. Navigate parenthood with the help of the Raising Curious Learners podcast. Nat. Northern maidenhair fern is a member of the Adiantaceae, a sub-family of the Pteridaceae family. A recent paper about the genus, Kessler & al. Ferns — Polypodiaceae & Pteridaceae: Polypody & Brake Families Ferns are not flowering plants. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Occurrence Adiantum is a common fern. 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. 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. It grows in shady places. NOW 50% OFF! Examples of sori and arrangements of sporangia in various species of ferns. It is a small herb consisting of stem, roots and leaves. 1. 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. Learn ferns with free interactive flashcards. Britannica Kids Holiday Bundle! A widespread type of indusium…. Woodwardia, sori oblong, parallel to ribs. 3. The life cycle of Adiantum shows heteromorphic alternation of generation. The base chromosome numbers (indicated by the symbol x) have been used for classification purposes. 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. They are usually described as having a rachis that for… One is the so-called false indusium, a rolled-over leaf margin under which sporangia form and mature. These are also grown for ornamental purposes. Commonly, the base number is uniform for a genus or family, or it ranges around a given number. Petris and Adiantum, sporangia covered by the edge of leaf. indusium : The sorus may simply be tucked protectively under the leaf edge (below).. V.S. 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. 4. Sporophyte. A widespread type of indusium… It can be grown in a terrarium, potted, or in pockets of limestone rocks. ... and are protected by bent margin of the leaflet, forming false indusium. 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. 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. Fern Facts. Vertical Section through fern leaf showing a sorus with indusium sporangium . 2006, 2008).More recently, PPG I (2016) accept 53 genera and an estimated 1211 species. Approximately 45 percent of the extant species of ferns are such neopolyploids. Adiantum is homosporous. Stem is a short, thick and underground, usually unbranched horizontally growing rhizome. Choose from 500 different sets of ferns flashcards on Quizlet. (2) A line of sporangia along the leaf edge, protected usually by a rolled-over and modified laminar margin, is represented by Pteris. 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. The taxonomic treatment of Adiantum raddianum has frequently changed. 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). Study Resources. Ord.—Filices. Adiantum pedatum is a part of the Adiantum pedatum complex comprising of three other species, Adiantum aleuticum, Adiantum myriosorum and Adiantum viridimontanum. 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. It prefers to grow in moist and 8 shady habitats. In Adiantum, the sori are borne submarginally at the distal end on the under surface of the leaflets. Such sori probably arose by the fusion of smaller clusters of sori. Those species belonging to the Adiantum pedatum complex are characterised by pedately-divided frond clusters growing from clump-forming rhizomes. The sporophyte is dominant and the gametophyte is small and reduced but separate and independent. Leaf of Adiantum … 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 sori are green but become dark brown when ripe. estimates c. 225 species, widely distributed from cold temperatures to tropics, most of them occurring … 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. The whole plant of the Adiantum pedatum, Linné, and Adiantum capillus Veneris, Linné. 1753. The reflexed margin is known as false indusium. The sporangia are often clustered into round or oblong dots (sori), and these are sometimes covered by a thin skin (indusium). The shape of the frond in A. pedatum, A. aleuticum, and A. viridimontanum is very similar. The sporophyte produces a large number of sori (singular sorus). 12. The genus Adiantum L. is a large and diverse group of ferns in the Old and New World trop-ics. Southern Maidenhair Fern is a popular horticultural species, and many varieties are available from nurseries. Visit the post for more. 1. Life Cycle. 489 TAXON 67 (3) • June 2018: 488–502 Huiet & al. Pl. The familiar genus Osmunda, for example, has x = 22, Pteris 29, Asplenium 36, Dryopteris 41, Botrychium 45, and Pteridium 52. leaflets. 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 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 common specie of this genus is Adiantum Capillus-Veneris. Species with both diploid and tetraploid forms are common, especially among widespread, abundant ferns. So it forms false indusium. • Phylogeny of Adiantum (Pteridaceae) Version of Record Fig. One is the so-called false indusium, a rolled-over leaf margin under which sporangia form and mature. 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. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Individual sporangia are easily visible around the edge of each sorus. Main Menu; ... Members of the family all have intramarginal, linear sori with a flap-like indusium arising along one edge. Sporangia and especially sori have traditionally provided the most important characters for fern classification. The genus is absent from dry areas in the interior of the continent. Vegetative reproduction occurs by fragmentation of rhizome, adventitious buds (e.g., Dryopteris), bulbils, etc. It is differentiated into stem, leaves and roots. Adiantum is a widespread fern which grows in mild climates. The sori are marginal but the reflex margins of the pinna form a protective membranous structure called false indusium (Figure 2.35). The name A. raddianum honours the Italian botanist Giuseppe Raddi (1770-1829). This has resulted in a number of synonyms, of which Adiantum cuneatum is still widely used. Indeed, many unrelated ferns were once classified together because of what are now believed to have been coincidental convergences in soral structure. Adiantum Linnaeus, Sp. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. Adiantum hispidulum occurs only as an escape from cultivation. 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). Polypodium and Phegopteris, sori round and uncovered. 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 2: 1094. 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. 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. Hand in hand with the reduction in size of single sporangia are seen more and more complex aggregations of sporangia known as sori. Adiantum L., commonly known as the maidenhair ferns, belongs to the Pteridaceae, a family with c. 50 genera and 950 species (Smith & al. Adiantum pedatum Linnaeus maidenhair fern Family: Pteridaceae . The study of chromosomes, hybrids, and breeding systems has revealed much of value in understanding ferns. Dryopteris) or turned margin of the sporophyll (false indusium, e.g. 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. This fern species is an important ornamental and more than seventy cultivars have been developed. The spores are produced in sporangia. Because 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. The leaflets and leaves having sori or sporangia are called sporophylls. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. 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. Adiantum has what is called a false indusium, a flap of tissue covering the sori originating from the leaf blade margin. Ferns overall still have relatively high levels of polyploidy, but these polyploids are all of relatively recent origin. Paraphyses usually are hairs or modifications of hairs that arise among the sporangia or on the sporangial stalk or capsule. They lack the separate male and female structures that form the basis of most flowering plants' reproductive processes. It is found in the plains of the Punjab. General structure The vegetative plant body is a sporophyte. frond. Duke University Libraries. When spores fall on a suitably moist, shady place, they begin the fern's reproductive cycle. Adiantum is among the most distinctive and easily recognized leptosporangiate fern genera. A group of sporangia forms sori. Introduction. 3. In ferns, spores are contained within cases called sporangia that are located on the underside of leaves. Notes on Taxonomy and Nomenclature Top of page. Sori with hood-like indusia. The petioles of the leaves are shining black and brittle. A sorus may be protected by an umbrella-like indusium, as shown below. . 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). It is found on moist walls or rocky places. The petioles of the frond in A. pedatum, A. aleuticum, Adiantum, etc an indusium are. 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