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Lichenology
Lichenology is the branch of mycology that studies the lichens, symbiotic organisms made up of an intimate symbiotic association of a microscopic alga (or a cyanobacterium) with a Hypha, filamentous fungus. Lichens are chiefly characterized by this symbiosis. Study of lichens draws knowledge from several disciplines: mycology, phycology, microbiology and botany. Scholars of lichenology are known as lichenologists. Study of lichens is conducted by both professional and amateur lichenologists. Methods for species identification include reference to single-access keys on lichens. An example reference work is ''Lichens of North America'' (2001) by Irwin M. Brodo, Sylvia Sharnoff and Stephen Sharnoff and that book's 2016 expansion, ''Keys to Lichens of North America: Revised and Expanded'' by the same three authors joined by Susan Laurie-Bourque. A chemical spot test (lichen), spot test can be used to detect the presence of certain lichen products which can be characteristic of a gi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lichenologists
Lichenology is the branch of mycology that studies the lichens, symbiotic organisms made up of an intimate symbiotic association of a microscopic alga (or a cyanobacterium) with a filamentous fungus. Lichens are chiefly characterized by this symbiosis. Study of lichens draws knowledge from several disciplines: mycology, phycology, microbiology and botany. Scholars of lichenology are known as lichenologists. Study of lichens is conducted by both professional and amateur lichenologists. Methods for species identification include reference to single-access keys on lichens. An example reference work is ''Lichens of North America'' (2001) by Irwin M. Brodo, Sylvia Sharnoff and Stephen Sharnoff and that book's 2016 expansion, ''Keys to Lichens of North America: Revised and Expanded'' by the same three authors joined by Susan Laurie-Bourque. A chemical spot test can be used to detect the presence of certain lichen products which can be characteristic of a given lichen species. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhizocarpon Geographicum On Quartz
''Rhizocarpon'' is a genus of crustose, saxicolous (or sometimes lichenicolous), lichens in the family Rhizocarpaceae. The genus is common in arctic-alpine environments, but also occurs throughout temperate, subtropical, and even tropical regions. They are commonly known as map lichens because of the prothallus forming border-like bands between colonies in some species, like the common map lichen (''Rhizocarpon geographicum''). Taxonomy and phylogeny Together with three small genera (''Catolechia'', ''Poeltinula'' and ''Epilichen''), ''Rhizocarpon'' constitutes the family Rhizocarpaceae. Historically, ca 389 names have been used. However, many species concepts are ill-defined, many names have been synonymized and new species are regularly being described, so true number of species is not entirely clear as of now, but is estimated to be around 200. In molecular work, the genus has also been shown to be paraphyletic, with closely related genera being nested within ''Rhizocarpon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spot Test (lichen)
A spot test in lichenology is a spot analysis used to help identify lichens. It is performed by placing a drop of a chemical reagent on different parts of the lichen and noting the colour change (or lack thereof) associated with application of the chemical. The tests are routinely encountered in dichotomous keys for lichen species, and they take advantage of the wide array of lichen products (secondary metabolites) produced by lichens and their uniqueness among taxa. As such, spot tests reveal the presence or absence of chemicals in various parts of a lichen. They were first proposed as a method to help identify species by the Finnish lichenologist William Nylander in 1866. Three common spot tests use either 10% aqueous KOH solution (K test), saturated aqueous solution of bleaching powder or calcium hypochlorite (C test), or 5% alcoholic ''p''-phenylenediamine solution (P test). The colour changes occur due to presence of particular secondary metabolites in the lichen. In ide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethnolichenology
Ethnolichenology is the study of the relationship between lichens and people. Lichens have and are being used for many different purposes by human cultures across the world. The most common human use of lichens is for dye, but they have also been used for medicine, food and other purposes. Lichens for dye Lichens are a common source of natural dyes. The lichen dye is usually extracted by either boiling water or ammonia fermentation. Although usually called ammonia fermentation, this method is not actually a fermentation and involves letting the lichen steep in ammonia (traditionally urine) for at least two to three weeks. In North America the most significant lichen dye is '' Letharia vulpina''. Indigenous people through most of this lichen's range in North America traditionally make a yellow dye from this lichen by boiling it in water. Many of the traditional dyes of the Scottish Highlands were made from lichens including red dyes from the cudbear lichen, '' Lecanora tartarea' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lichen Anatomy And Physiology
Lichen anatomy and physiology is very different from the anatomy and physiology of the fungus and/or algae and/or cyanobacteria that make up the lichen when growing apart from the lichen, either naturally, or in culture. The fungal partner is called the mycobiont. The photosynthetic partner, algae or cyanobacteria, is called the photobiont. The body of a lichens that does not contain reproductive parts of the fungus is called the thallus. The thallus is different from those of either the fungus or alga growing separately. The fungus surrounds the algal cells, often enclosing them within complex fungal tissues unique to lichen associations. In many species the fungus penetrates the algal cell wall, forming penetration pegs or haustoria similar to those produced by pathogenic fungi.F.S. Dobson (2000) Lichens, an illustrated guide to the British and Irish species. Richmond Publishing Co. Ltd., Slough, UKR. Honegger (1988) Mycobionts. Chapter 3 in T.H. Nash (ed.) (1996) Lichen Biology. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lichen Morphology
Lichen morphology describes the external appearance and structures of a lichen. These can vary considerably from species to species. Lichen growth forms are used to group lichens by "vegetative" thallus types, and forms of "non-vegetative" reproductive parts. Some lichen thalli have the aspect of leaves (foliose lichens); others cover the substrate like a crust (crustose lichens) (''illustration, right''), others such as the genus ''Ramalina'' adopt shrubby forms (fruticose lichens), and there are gelatinous lichens such as the genus ''Collema''. Although the form of a lichen is determined by the genetic material of the fungal partner, association with a photobiont is required for the development of that form. When grown in the laboratory in the absence of its photobiont, a lichen fungus develops as an undifferentiated mass of hyphae. If combined with its photobiont under appropriate conditions, its characteristic form emerges, in the process called morphogenesis.Brodo, Sharnof ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lichens And Nitrogen Cycling
Some types of lichen are able to fix nitrogen from the atmosphere. This process relies on the presence of cyanobacteria as a partner species within the lichen. The ability to fix nitrogen enables lichen to live in nutrient-poor environments. Lichen can also extract nitrogen from the rocks on which they grow. Nitrogen fixation, and hence the abundance of lichen and their host plants, may be decreased by application of nitrogen-based agricultural fertilizer and by atmospheric pollution. The nitrogen cycle The nitrogen cycle is one of the Earth's biogeochemical cycles. It involves the conversion of nitrogen into different chemical forms. The main processes of the nitrogen cycle are the fixation, ammonification, nitrification, and denitrification. As one of the macronutrients, nitrogen plays an important role in plant growth. The nitrogen cycle is affected by environmental factors. For example, in the subarctic heath, increase in temperature can cause nitrogen fixation to increase or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lichenometry
In archaeology, palaeontology, and geomorphology, lichenometry is a geomorphic method of geochronologic dating that uses lichen growth to determine the age of exposed rock, based on a presumed specific rate of increase in radial size over time.Lichens in relation to management issues in the Sierra Nevada national parks, McCune, B., J. Grenon, and E. Martin, L. Mutch, Sierra Nevada Network, Cooperative agreement CA9088A0008. Oregon State University, Corvallis, Oregon, and Sequoia and Kings Canyon National Parks, Three Rivers, California/ref> Measuring the diameter of the largest lichen of a species on a rock surface can therefore be used to determine the length of time the rock has been exposed. Lichen can be preserved on old rock faces for up to 10,000 years, providing the maximum age limit of the technique, but it is most accurate (within 10% error) when applied to surfaces that have been exposed for less than 1,000 years. (The practical limit of the technique might be 4,000 to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lichen Products
Lichen products, also known as lichen substances, are organic compounds produced by a lichen. Specifically, they are secondary metabolites. Lichen products are represented in several different chemical classes, including terpenoids, orcinol derivatives, chromones, xanthones, depsides, and depsidones. Over 800 lichen products of known chemical structure have been reported in the scientific literature, and most of these compounds are exclusively found in lichens. Examples of lichen products include usnic acid (a dibenzofuran), atranorin (a depside), lichexanthone (a xanthone), salazinic acid (a depsidone), and isolichenan, an α-glucan. Many lichen products have biological activity, and research into these effects is ongoing. Biosynthesis Most lichen products are biochemically synthesized via the acetyl-polymalonyl pathway (also known as polyketide pathway), while only a few originate from the mevalonate and shikimate biosynthetic pathways. Occurrence Lichen products accumulate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edible Lichens
Edible lichens are lichens that have a cultural history of use as a food. Although almost all lichen are edible (with some notable poisonous exceptions like the wolf lichen, powdered sunshine lichen, and thground lichen, not all have a cultural history of usage as an edible lichen. Often lichens are merely famine foods eaten in times of dire needs, but in some cultures lichens are a staple food or even a delicacy. Some lichens are a source of vitamin D. Uses Although there are many lichen species throughout the world, only a few species of lichen are known to be both edible and provide any nutrition. Two problems often encountered with eating lichens is that they usually contain mildly toxic secondary compounds, and that lichen polysaccharides are generally indigestible to humans. Many human cultures have discovered preparation techniques to overcome these problems. Lichens are often thoroughly washed, boiled, or soaked in ash water to help remove secondary compounds. Recen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alga
Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular microalgae, such as cyanobacteria, '' Chlorella'', and diatoms, to multicellular macroalgae such as kelp or brown algae which may grow up to in length. Most algae are aquatic organisms and lack many of the distinct cell and tissue types, such as stomata, xylem, and phloem that are found in land plants. The largest and most complex marine algae are called seaweeds. In contrast, the most complex freshwater forms are the Charophyta, a division of green algae which includes, for example, ''Spirogyra'' and stoneworts. Algae that are carried passively by water are plankton, specifically phytoplankton. Algae constitute a polyphyletic group because they do not include a common ancestor, and although eukaryotic algae with chlorophyll-bearing plastids seem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lichen
A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), mutualistic relationship.Introduction to Lichens – An Alliance between Kingdoms . University of California Museum of Paleontology. . Lichens are the lifeform that first brought the term symbiosis (as ''Symbiotismus'') into biological context. Lichens have since been recognized as important actors in nutrient cycling and producers which many higher trophic feeders feed on, such as reindeer, gastropods, nematodes, mites, and springtails. Lichens have properties different from those of their component organisms. They come in man ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
