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Annulus (botany)
An annulus in botany is for ferns an arc or a ring of specialized cells on the sporangium. These cells are arranged in a single row, and are associated with the release or dispersal of spores. In mosses it is a ring of cells around the tip of the sporangium. In flowers it is a ring of hairs within the flower tube. Ferns In leptosporangiate ferns, the annulus located on the outer rim of the sporangium and serves in spore dispersal. It consists typically of a ring or belt of dead water-filled cells with differentially thickened cell walls that stretches about two-thirds around each sporangium in leptosporangiate ferns. The thinner walls on the outside allow water to evaporate quickly under dry conditions. This Dehiscence (botany), dehiscence causes the cells to shrink and a contraction and straightening of the annulus ring, eventually rupturing the sporangial wall by ripping apart thin-walled lip cells on the opposite side of the sporangium. The annulus slowly straightens and conti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sporangium
A sporangium (from Late Latin, ; : sporangia) is an enclosure in which spores are formed. It can be composed of a unicellular organism, single cell or can be multicellular organism, multicellular. Virtually all plants, fungus, fungi, and many other groups form sporangia at some point in their biological life cycle, life cycle. Sporangia can produce spores by mitosis, but in land plants and many fungi, sporangia produce genetically distinct haploid spores by meiosis. It's outdated name, sporange, is one of the few perfect rhymes for Orange (colour), orange. Fungi In some phyla of fungi, the sporangium plays a role in asexual reproduction, and may play an indirect role in sexual reproduction. The sporangium forms on the sporangiophore and contains Ploidy, haploid Cell nucleus, nuclei and cytoplasm. Spores are formed in the sporangiophore by encasing each haploid nucleus and cytoplasm in a tough outer membrane. During asexual reproduction, these spores are dispersed via wind and g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ONF Fig 02 - Sporangium Of Polypodium Vulgare , in French, a public organization
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ONF may refer to: * ONF (band), a South Korean boy band * Official National Front, a defunct political party in the United Kingdom * Office national des forêts, the French national forest agency * Ocala National Forest, in Florida * Old Northern French, another name for the Old Norman dialect * Open Networking Foundation, a nonprofit trade organization * All-Russia People's Front (), a political organization * The National Film Board of Canada The National Film Board of Canada (NFB; ) is a Canadian public film and digital media producer and distributor. An agency of the Government of Canada, the NFB produces and distributes documentary films, animation, web documentaries, and altern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Funaria Hygrometrica (f, 144605-481033) 0964
''Funaria hygrometrica'', the bonfire moss or common cord-moss, is a type of water moss which grows on shady, moist soil. It can also be found on moist walls and the crevices of rocks and places where recent fires have taken place. It has been reported to grow in Niagara Cave, an artificially illuminated cave devoid of natural light. Under such conditions, its growth form changes so that the internodes lengthen and the leaves become longer and narrower. The plant body is green, soft and upright, about half an inch tall. The rhizoids present in this species are multi-cellular and branched. They have oblique septa. The main axis of the plant, which is upright, bears a set of spirally arranged, sessile leaves having a clearly distinguishable midrib. At the apex of the main plant axis, the antheridium is borne. This is the male part of the shoot. A lateral branch from the main plant axis bears the female shoot archegonium at its meristem. Experiments have shown that F. hygromet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leptosporangiate Fern
The Polypodiidae, commonly called leptosporangiate ferns, formerly Leptosporangiatae, are one of four subclasses of ferns, the largest of these being the largest group of living ferns, including some 11,000 species worldwide. The group has also been treated as the class Pteridopsida or Polypodiopsida, although other classifications assign them a different rank. Older names for the group include Filicidae and Filicales, although at least the "water ferns" (now the Salviniales) were then treated separately. The leptosporangiate ferns are one of the four major groups of ferns, with the other three being the eusporangiate ferns comprising the marattioid ferns (Marattiidae, Marattiaceae), the horsetails (Equisetiidae, Equisetaceae), and whisk ferns and moonworts. There are approximately 8465 species of living leptosporangiate ferns, compared with about 2070 for all other ferns, totalling 10535 species of ferns. Almost a third of leptosporangiate fern species are epiphytes. These ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spore Dispersal
In biology, a spore is a unit of sexual (in fungi) or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, fungi and protozoa. They were thought to have appeared as early as the mid-late Ordovician period as an adaptation of early land plants. Bacterial spores are not part of a sexual cycle, but are resistant structures used for survival under unfavourable conditions. Myxozoan spores release amoeboid infectious germs ("amoebulae") into their hosts for parasitic infection, but also reproduce within the hosts through the pairing of two nuclei within the plasmodium, which develops from the amoebula. In plants, spores are usually haploid and unicellular and are produced by meiosis in the sporangium of a diploid sporophyte. In some rare cases, a diploid spore is also produced in some algae, or fungi. Under favourable conditions, the spore ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leptosporangiate Ferns
The Polypodiidae, commonly called leptosporangiate ferns, formerly Leptosporangiatae, are one of four subclasses of ferns, the largest of these being the largest group of living ferns, including some 11,000 species worldwide. The group has also been treated as the class Pteridopsida or Polypodiopsida, although other classifications assign them a different rank. Older names for the group include Filicidae and Filicales, although at least the "water ferns" (now the Salviniales) were then treated separately. The leptosporangiate ferns are one of the four major groups of ferns, with the other three being the eusporangiate ferns comprising the marattioid ferns (Marattiidae, Marattiaceae), the horsetails (Equisetiidae, Equisetaceae), and whisk ferns and moonworts. There are approximately 8465 species of living leptosporangiate ferns, compared with about 2070 for all other ferns, totalling 10535 species of ferns. Almost a third of leptosporangiate fern species are epiphytes. These ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dehiscence (botany)
Dehiscence is the splitting of a mature plant structure along a built-in line of weakness to release its contents. This is common among fruits, anthers and sporangia. Sometimes this involves the complete detachment of a part. Structures that open in this way are said to be dehiscent. Structures that do not open in this way are called indehiscent, and rely on other mechanisms such as decay, digestion by herbivores, or predation to release the contents. A similar process to dehiscence occurs in some flower buds (e.g., '' Platycodon'', '' Fuchsia''), but this is rarely referred to as dehiscence unless circumscissile dehiscence is involved; anthesis is the usual term for the opening of flowers. Dehiscence may or may not involve the loss of a structure through the process of abscission. The lost structures are said to be caducous. Association with crop breeding Manipulation of dehiscence can improve crop yield since a trait that causes seed dispersal is a disadvantage for fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spore
In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the Biological life cycle, life cycles of many plants, algae, fungus, fungi and protozoa. They were thought to have appeared as early as the mid-late Ordovician period as an adaptation of early land plants. Bacterial spores are not part of a sexual cycle, but are resistant structures used for survival under unfavourable conditions. Myxozoan spores release amoeboid infectious germs ("amoebulae") into their hosts for parasitic infection, but also reproduce within the hosts through the pairing of two nuclei within the plasmodium, which develops from the amoebula. In plants, spores are usually haploid and unicellular and are produced by meiosis in the sporangium of a diploid sporophyte. In some rare cases, a diploid spore is also p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cavitation
Cavitation in fluid mechanics and engineering normally is the phenomenon in which the static pressure of a liquid reduces to below the liquid's vapor pressure, leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure, these cavities, called "bubbles" or "voids", collapse and can generate shock waves that may damage machinery. These shock waves are strong when they are very close to the imploded bubble, but rapidly weaken as they propagate away from the implosion. Cavitation is a significant cause of wear in some engineering contexts. Collapsing voids that implode near to a metal surface cause cyclic stress through repeated implosion. This results in surface fatigue of the metal, causing a type of wear also called "cavitation". The most common examples of this kind of wear are to pump impellers, and bends where a sudden change in the direction of liquid occurs. Cavitation is usually divided into two classes of behavior. ''In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moss
Mosses are small, non-vascular plant, non-vascular flowerless plants in the taxonomic phylum, division Bryophyta (, ) ''sensu stricto''. Bryophyta (''sensu lato'', Wilhelm Philippe Schimper, Schimp. 1879) may also refer to the parent group bryophytes, which comprise Marchantiophyta, liverworts, mosses, and hornworts. Mosses typically form dense green clumps or mats, often in damp or shady locations. The individual plants are usually composed of simple leaf, leaves that are generally only one cell thick, attached to a plant stem, stem that may be branched or unbranched and has only a limited role in conducting water and nutrients. Although some species have conducting tissues, these are generally poorly developed and structurally different from similar tissue found in vascular plants. Mosses do not have seeds and after fertilisation develop sporophytes with unbranched stalks topped with single capsules containing sporangium, spores. They are typically tall, though some species ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
