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Xyleborus (lichen)
''Xyleborus'' is a small genus of lichen-forming fungi in the family Stereocaulaceae. It comprises two species. The genus was circumscribed in 2009 by Richard C. Harris and Douglas Ladd with '' Xyleborus sporodochifer'' assigned as the type species. A second species, '' X. nigricans'', was added to the genus in 2015. This genus is only found in North America, in the Ozarks, the Appalachians, and the Mid-Atlantic Coastal Plain. ''Xyleborus'' species only grow as a crust with black apothecia on weathered logs and stumps in intact forests. Taxonomy ''Xyleborus'' was erected in 2007 by Richard C. Harris and Douglas Ladd after they encountered an unusual crustose lichen with abundant white on seasoned oak logs in the Ozark Highlands. They treated that species, ''X. sporodochifer'', as the type and sole member of a new genus distinguished by its '' Micarea''-type asci, lignicolous habit, and conspicuous sporodochial cushions, all rare features among crustose lichens. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allopatric
Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow. Various geographic changes can arise such as the movement of continents, and the formation of mountains, islands, bodies of water, or glaciers. Human activity such as agriculture or developments can also change the distribution of species populations. These factors can substantially alter a region's geography, resulting in the separation of a species population into isolated subpopulations. The vicariant populations then undergo genetic changes as they become subjected to different selective pressures, experience genetic drift, and accumulate different mutations in the separated populations' gene pools. The barriers prevent the exchange of genetic information between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraphyses
Paraphyses are erect sterile filament-like support structures occurring among the reproductive apparatuses of fungi, ferns, bryophytes and some thallophytes. The singular form of the word is paraphysis. In certain fungi, they are part of the fertile spore-bearing layer. More specifically, paraphyses are sterile filamentous hyphal end cells composing part of the hymenium of Ascomycota and Basidiomycota interspersed among either the asci or basidia respectively, and not sufficiently differentiated to be called cystidia A cystidium (: cystidia) is a relatively large cell found on the sporocarp of a basidiomycete (for example, on the surface of a mushroom gill), often between clusters of basidia. Since cystidia have highly varied and distinct shapes that are o ..., which are specialized, swollen, often protruding cells. The tips of paraphyses may contain the pigments which colour the hymenium. In ferns and mosses, they are filament-like structures that are found on sporangi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hymenium
The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in others some cells develop into sterile cells called cystidia ( basidiomycetes) or paraphyses ( ascomycetes). Cystidia are often important for microscopic identification. The subhymenium consists of the supportive hyphae from which the cells of the hymenium grow, beneath which is the hymenophoral trama, the hyphae that make up the mass of the hymenophore. The position of the hymenium is traditionally the first characteristic used in the classification and identification of mushrooms. Below are some examples of the diverse types which exist among the macroscopic Basidiomycota and Ascomycota. * In agarics, the hymenium is on the vertical faces of the gills. * In boletes and polypores, it is in a spongy mass of downward-pointing tubes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Hydroxide
Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utilize its caustic nature and its reactivity toward acids. An estimated 700,000 to 800,000 tonnes were produced in 2005. KOH is noteworthy as the precursor to most soft and liquid soaps, as well as numerous potassium-containing chemicals. It is a white solid that is dangerously corrosive. Properties and structure KOH exhibits high thermal stability. Because of this high stability and relatively low melting point, it is often melt-cast as pellets or rods, forms that have low surface area and convenient handling properties. These pellets become tacky in air because KOH is hygroscopic. Most commercial samples are ca. 90% pure, the remainder being water and carbonates. Its dissolution in water is strongly exothermic. Concentrated aqueous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Reproduction
Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote that develops into an organism composed of cells with two sets of chromosomes ( diploid). This is typical in animals, though the number of chromosome sets and how that number changes in sexual reproduction varies, especially among plants, fungi, and other eukaryotes. In placental mammals, sperm cells exit the penis through the male urethra and enter the vagina during copulation, while egg cells enter the uterus through the oviduct. Other vertebrates of both sexes possess a cloaca for the release of sperm or egg cells. Sexual reproduction is the most common life cycle in multicellular eukaryotes, such as animals, fungi and plants. Sexual reproduction also occurs in some unicellular eukaryotes. Sexual reproduction does not occur in pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Metabolism
In biochemistry, secondary metabolism (also called specialized metabolism) is a term for pathways and small molecule products of metabolism that are involved in ecological interactions, but are not absolutely required for the survival of the organism. These molecules are sometimes produced by specialized cells, such as laticifers in plants. Secondary metabolites commonly mediate antagonistic interactions, such as competition and predation, as well as mutualistic ones such as pollination and resource mutualisms. Examples of secondary metabolites include antibiotics, pigments and scents. The opposite of secondary metabolites are primary metabolites, which are considered to be essential to the normal growth or development of an organism. Secondary metabolites are produced by many microbes, plants, fungi and animals, usually living in crowded habitats, where chemical defense represents a better option than physical escape. It is very hard to distinguish primary and secondary me ... [...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] |
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] |
Molecular Phylogenetics
Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to determine the processes by which diversity among species has been achieved. The result of a molecular phylogenetics, phylogenetic analysis is expressed in a phylogenetic tree. Molecular phylogenetics is one aspect of molecular systematics, a broader term that also includes the use of molecular data in Taxonomy (biology), taxonomy and biogeography. Molecular phylogenetics and molecular evolution correlate. Molecular evolution is the process of selective changes (mutations) at a molecular level (genes, proteins, etc.) throughout various branches in the tree of life (evolution). Molecular phylogenetics makes inferences of the evolutionary relationships that arise due to molecular evolution and results in the construction of a phylogenetic tre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conifer
Conifers () are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class (biology), class, Pinopsida. All Neontology, extant conifers are perennial plant, perennial woody plants with secondary growth. The majority are trees, though a few are shrubs. Examples include Cedrus, cedars, Pseudotsuga, Douglas-firs, Cupressaceae, cypresses, firs, junipers, Agathis, kauri, larches, pines, Tsuga, hemlocks, Sequoioideae, redwoods, spruces, and Taxaceae, yews.Campbell, Reece, "Phylum Coniferophyta". ''Biology''. 7th ed. 2005. Print. p. 595. As of 2002, Pinophyta contained seven families, 60 to 65 genera, and more than 600 living species. Although the total number of species is relatively small, conifers are ecology, ecologically important. They are the dominant plants over large areas of land, most notably ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resin
A resin is a solid or highly viscous liquid that can be converted into a polymer. Resins may be biological or synthetic in origin, but are typically harvested from plants. Resins are mixtures of organic compounds, predominantly terpenes. Common resins include amber, hashish, frankincense, myrrh and the animal-derived resin, shellac. Resins are used in varnishes, adhesives, food additives, incenses and perfumes. Resins protect plants from insects and pathogens, and are secreted in response to injury. Resins repel herbivores, insects, and pathogens, while the volatile natural phenol, phenolic compounds may attract benefactors such as predators of insects that attack the plant. Composition Most plant resins are composed of terpenes. Specific components are alpha-Pinene, alpha-pinene, pinene, beta-pinene, carene, delta-3 carene, and sabinene, the monocyclic terpenes limonene and terpinolene, and smaller amounts of the tricyclic sesquiterpenes, longifolene, caryophyllene, and cad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
