Related Research Articles
Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The defining feature of this fungal group is the "ascus", a microscopic sexual structure in which nonmotile spores, called ascospores, are formed. However, some species of the Ascomycota are asexual, meaning that they do not have a sexual cycle and thus do not form asci or ascospores. Familiar examples of sac fungi include morels, truffles, brewer's yeast and baker's yeast, dead man's fingers, and cup fungi. The fungal symbionts in the majority of lichens such as Cladonia belong to the Ascomycota.
Lichenology is the branch of mycology that studies the lichens, symbiotic organisms made up of an intimate symbiotic association of a microscopic alga with a filamentous fungus.
A lichen is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. Lichens have properties different from those of their component organisms. They come in many colors, sizes, and forms and are sometimes plant-like, but lichens are not plants. They may have tiny, leafless branches (fruticose); flat leaf-like structures (foliose); crust-like, adhering tightly to a surface (substrate) like a thick coat of paint (crustose); a powder-like appearance (leprose); or other growth forms.
Thallus, from Latinized Greek θαλλός (thallos), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms were previously known as the thallophytes, a polyphyletic group of distantly related organisms. An organism or structure resembling a thallus is called thalloid, thallodal, thalliform, thalline, or thallose.
Victoria Land is a region in eastern Antarctica which fronts the western side of the Ross Sea and the Ross Ice Shelf, extending southward from about 70°30'S to 78°00'S, and westward from the Ross Sea to the edge of the Antarctic Plateau. It was discovered by Captain James Clark Ross in January 1841 and named after Queen Victoria. The rocky promontory of Minna Bluff is often regarded as the southernmost point of Victoria Land, and separates the Scott Coast to the north from the Hillary Coast of the Ross Dependency to the south.
A holdfast is a root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, benthic cnidarians, and sponges, to the substrate.
The Cladoniaceae are a family of lichenized fungi in the order Lecanorales. It is one of the largest families of lichen-forming fungi, with about 560 species distributed amongst 17 genera. The reindeer moss and cup lichens (Cladonia) belong to this family. The latter genus, which comprises about 500 species, forms a major part of the diet of large mammals in taiga and tundra ecosystems. Many Cladoniaceae lichens grow on soil, but other can use decaying wood, tree trunks, and, in a few instances, rocks as their substrate. They grow in places with high humidity, and cannot tolerate aridity.
Fragmentation in multicellular or colonial organisms is a form of asexual reproduction or cloning, where an organism is split into fragments. Each of these fragments develop into mature, fully grown individuals that are clones of the original organism.
This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary of leaf morphology. For other related terms, see Glossary of phytopathology and List of Latin and Greek words commonly used in systematic names.
Lobaria pulmonaria is a large epiphytic lichen consisting of an ascomycete fungus and a green algal partner living together in a symbiotic relationship with a cyanobacterium—a symbiosis involving members of three kingdoms of organisms. Commonly known by various names like tree lungwort, lung lichen, lung moss, lungwort lichen, oak lungs or oak lungwort, it is sensitive to air pollution and is also harmed by habitat loss and changes in forestry practices. Its population has declined across Europe and L. pulmonaria is considered endangered in many lowland areas. The species has a history of use in herbal medicines, and recent research has corroborated some medicinal properties of lichen extracts.
An isidium is a vegetative reproductive structure present in some lichens. Isidia are outgrowths of the thallus surface, and are corticated, usually with a columnar structure, and consisting of both fungal hyphae and algal cells. They are fragile structures and may break off and be distributed by wind, animals, and splashing raindrops. In terms of structure, isidia may be described as warty, cylindrical, clavate (club-shaped), scale-like, coralloid (coral-shaped), simple, or branched.
Acarospora is a genus of lichenized fungi in the family Acarosporaceae. Most species in the genus are crustose lichens that grow on rocks in open and arid places all over the world. They may look like a cobblestone road or cracked up old paint, and are commonly called cobblestone lichens or cracked lichens,. They usually grow on rock, but some grow on soil (terricolous) or on other lichens. Some species in the genus are fungi that live as parasites on other lichens. Acarospora is a widely distributed genus, with about 128 species according to a 2008 estimate.
Cryptothecia rubrocincta is a species of lichen in the fungal family Arthoniaceae. The species is distributed in subtropical and tropical locations throughout the southeastern United States, as well as Central and South America, and has been collected infrequently in a few locales in Africa. The body of the lichen forms continuous, circular crust-like patches on dead wood, readily recognizable by the prominent red pigment. The older, central region is covered with red, spherical to cylindrical granules. Moving outwards from the center, zones of color may be distinguished, the first gray-green, the second white, and finally a bright red cottony rim. The red and green colors of this unmistakable woodland lichen give the appearance of a Christmas wreath, suggestive of its common North American name, the Christmas wreath lichen. The red pigment, called chiodectonic acid, is one of several chemicals the lichen produces to help tolerate inhospitable growing conditions.
Nephroma is a genus of medium to large foliose lichens. The genus has a widespread distribution and contains 36 species. They are sometimes called kidney lichens, named after the characteristic kidney-shaped apothecia that they produce on the lower surface of their lobe tips, which often curl upwards and thus are visible from above. Sterile specimens that do not have apothecia can look somewhat like Melanelia, Peltigera, Platismatia, or Asahinea. Most species grow either on mossy ground or rocks, or on trees.
A fruticose lichen is a form of lichen fungi that is characterized by a coral-like shrubby or bushy growth structure. It is composed of a thallus and a holdfast. It is formed from a symbiotic relationship of a photobiont such as cyanobacteria and two mycobionts. Fruticose lichen is composed of a complex vegetation structure, and characterized by an ascending, bushy or pendulous appearance. While lichen communities are mainly controlled by water and light, vegetative dispersal and filamentous growth in fruticose lichen is often associated with areas of low elevation. Fruticose lichens can endure high degrees of desiccation. They grow very slowly and will often occur in extreme habitats such as on tree barks, on rock surfaces and on soils in the Arctic and mountain regions.
Crustose lichens form a crust that strongly adheres to the substrate, making separation from the substrate impossible without destruction. The basic structure of crustose lichens consists of a cortex layer, an algal layer, and a medulla. The upper cortex layer is differentiated and is usually pigmented. The algal layer lies beneath the cortex. The medulla fastens the lichen to the substrate and is made up of fungal hyphae. The surface of crustose lichens is characterized by branching cracks that periodically close in response to climatic variations such as alternate wetting and drying regimes.
Foliose lichen is one of a variety of lichens, which are complex organisms that arise from the symbiotic relationship between fungi and a photosynthetic partner, typically algae. This partnership allows lichen to live in diverse climates that can range from cold, dry mountains to wet, warm valleys. Lichens develop quite slowly with recorded growth rates of 0.01–27mm/year depending on the species. Their lifespan averages between 30 and 60 years.
Lichens are grouped by common lichen growth forms. There are a wide range of growth forms (morphology). These groupings may not be consistent with lichen taxonomy, since lichens with similar growth forms are not necessarily related by ancestry. Groups based on growth may overlap and have borderline cases. A species usually has the same overall growth form wherever it is found, but not always.
Lichen morphology includes lichen growth forms used to group lichens by "vegetative" thallus types, and forms of "non-vegetative" reproductive parts. Some lichen thalli have the aspect of leaves ; others cover the substrate like a crust, others such as the genus Ramalina adopt shrubby forms, and there are gelatinous lichens such as the genus Collema.
In lichens, rhizines are multicellular root-like structures, arising mostly from the lower surface. A lichen with rhizines is termed rhizinate, while a lichen lacking rhizines is termed erhizinate. Rhizines serve only to anchor the lichen to their substrate; they do not absorb nutrients as do plant roots. Characteristics of the rhizines are used to identify lichens, for example: whether they are dense or sparse, whether they are uniformly distributed or clumped in specific areas, and whether they are straight or branched. Only foliose lichens may possess rhizines, not crustose or fruticose lichens, which lack a lower cortex.
References
 | This article about lichens or lichenology is a stub. You can help Wikipedia by expanding it. |