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Pyrenodesmia Vernadskiensis
''Pyrenodesmia'' is a genus of lichen-forming fungi in the family Teloschistaceae. The genus currently includes 23 recognized species but is believed to contain many more unnamed taxa. The genus was circumscribed in 1852 by Italian lichenologist Abramo Bartolommeo Massalongo. It is characterised by the complete absence of anthraquinones and the presence of Sedifolia-gray pigments in both the thallus and apothecia. These lichens are typically found in calcareous outcrops in the Northern Hemisphere, with biodiversity centres in the Mediterranean basin, Central Asia, and arid regions of western North America. Taxonomy The genus ''Pyrenodesmia'' was circumscribed by Abramo Bartolommeo Massalongo (1852). In his original conception, Massalongo included four species (''P. agardhiana'', ''P. chalybaea'', ''P. olivacea'', and ''P. variabilis'') and three infraspecific taxa (''P. variabilis'' β. ''lilacina'', ''P. variabilis'' δ. ''pulchella'', and ''P. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrenodesmia Variabilis
''Pyrenodesmia variabilis'' is a species of saxicolous lichen, saxicolous (rock-dwelling), crustose lichen in the family Teloschistaceae. Characteristics of the species include its dark, thallus, and its dark, (stalkless) (fruiting bodies). It occurs on nutrient-rich limestone surfaces in Northern Europe, North America, Central America, and Asia. Taxonomy The species was first species description, scientifically described in 1794 by Christiaan Hendrik Persoon, who called it ''Lichen variabilis''. Abramo Bartolommeo Massalongo transferred the taxon to the genus ''Pyrenodesmia'' in 1852, a genus he circumscription (taxonomy), circumscribed to include a group of four species (''P. agardhiana'', ''P. chalybaea'', ''P. olivacea'', and ''P. variabilis''), all of which lacked anthraquinones (a class of secondary metabolites common in the family Teloschistaceae), and contained instead the insoluble lichen pigment . As its botanical name, species epithet suggests, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensu Stricto
''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular concept, but it also appears in expressions that indicate the convention or context of the usage. Common qualifiers ''Sensu'' is the ablative case of the noun ''sensus'', here meaning "sense". It is often accompanied by an adjective (in the same case). Three such phrases are: * – "in the strict sense", abbreviation ''s.s.'' or ''s.str.''; * – "in the broad sense", abbreviation ''s.l.''; * – "in a relaxed, generous (or 'ample') sense", a similar meaning to ''sensu lato''. Søren Kierkegaard uses the phrase ''sensu eminenti'' to mean "in the pre-eminent r most important or significantsense". When appropriate, comparative and superlative adjectives may also be used to convey the meaning of "more" or "most". Thus ''sensu strict ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrenodesmia Badioreagens
''Pyrenodesmia'' is a genus of lichen-forming fungi in the family Teloschistaceae. The genus currently includes 23 recognized species but is believed to contain many more unnamed taxa. The genus was circumscribed in 1852 by Italian lichenologist Abramo Bartolommeo Massalongo. It is characterised by the complete absence of anthraquinones and the presence of Sedifolia-gray pigments in both the thallus and apothecia. These lichens are typically found in calcareous outcrops in the Northern Hemisphere, with biodiversity centres in the Mediterranean basin, Central Asia, and arid regions of western North America. Taxonomy The genus ''Pyrenodesmia'' was circumscribed by Abramo Bartolommeo Massalongo (1852). In his original conception, Massalongo included four species (''P. agardhiana'', ''P. chalybaea'', ''P. olivacea'', and ''P. variabilis'') and three infraspecific taxa (''P. variabilis'' β. ''lilacina'', ''P. variabilis'' δ. ''pulchella'', and ''P. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpine Zone
Alpine tundra is a type of natural region or biome that does not contain trees because it is at high elevation, with an associated alpine climate, harsh climate. As the latitude of a location approaches the poles, the threshold elevation for alpine tundra gets lower until it reaches sea level and merges with tundra#Arctic tundra, polar tundra. The high elevation causes an adverse climate, which is too cold and windy to support tree growth. Alpine tundra ecotone, transitions to sub-alpine forests below the tree line; stunted forests occurring at the forest-tundra ecotone are known as ''krummholz''. With increasing elevation it ends at the snow line where snow and ice persist through summer. Alpine tundra occurs in mountains worldwide. The flora of the alpine tundra is characterized by dwarf shrubs close to the ground. The cold climate of the alpine tundra is caused by adiabatic cooling of air, and is similar to polar climate. Geography Alpine tundra occurs at high enough altit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siliceous
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant families of materials, existing as a compound of several minerals and as a synthetic product. Examples include fused quartz, fumed silica, opal, and aerogels. It is used in structural materials, microelectronics, and as components in the food and pharmaceutical industries. All forms are white or colorless, although impure samples can be colored. Silicon dioxide is a common fundamental constituent of glass. Structure In the majority of silicon dioxides, the silicon atom shows tetrahedral coordination, with four oxygen atoms surrounding a central Si atomsee 3-D Unit Cell. Thus, SiO2 forms 3-dimensional network solids in which each silicon atom is covalently bonded in a tetrahedral manner to 4 oxygen atoms. In contrast, CO2 is a linear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saxicolous Lichen
A saxicolous lichen is a lichen that grows on rock. The prefix "sax" from the Latin means "rock" or "stone". Characteristics Saxicolous lichens exhibit very slow growth rates. They may develop on rock substrates for long periods of time, given the absence of external disturbances. The importance of the mineral composition of the rock substrate, as well as the elemental geochemistry Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the e ... is also important to the distribution of saxicolous lichens, but the relationship between the substrate influence on lichens, either chemical or textural, is still obscure. Communities of saxicolous lichens are often species-rich in terms of number. References Lichenology {{lichen-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
