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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 are not plants. They may have tiny, leafless branches (fruticose); flat leaf-like structures (foliose); grow crust-like, adhering tightly to a surface (substrate) like a thick coat of paint (crustose); have a powder-like appearance (leprose); or other growth forms.
Erik Acharius was a Swedish botanist who pioneered the taxonomy of lichens and is known as the "father of lichenology." Acharius was famously the last pupil of Carl Linnaeus.
Parmelia is a genus of medium to large foliose lichens. It has a global distribution, extending from the Arctic to the Antarctic continent but concentrated in temperate regions. There are about 40 species in Parmelia. In recent decades, the once large genus Parmelia has been divided into a number of smaller genera according to thallus morphology and phylogenetic relatedness.
Biological soil crusts are communities of living organisms on the soil surface in arid and semi-arid ecosystems. They are found throughout the world with varying species composition and cover depending on topography, soil characteristics, climate, plant community, microhabitats, and disturbance regimes. Biological soil crusts perform important ecological roles including carbon fixation, nitrogen fixation and soil stabilization; they alter soil albedo and water relations and affect germination and nutrient levels in vascular plants. They can be damaged by fire, recreational activity, grazing and other disturbances and can require long time periods to recover composition and function. Biological soil crusts are also known as biocrusts or as cryptogamic, microbiotic, microphytic, or cryptobiotic soils.
Vernon Ahmadjian was a distinguished professor at Clark University in Worcester, Massachusetts. He specialized in the symbiosis of lichens, and wrote several books and numerous publications on the subject.
Rhizocarpon geographicum is a species of lichen, which grows on rocks in mountainous areas of low air pollution. Each lichen is a flat patch bordered by a black line of fungal hyphae. These patches grow adjacent to each other, leading to the appearance of a map or a patchwork field.
Trebouxia is a unicellular green alga. It is a photosynthetic organism that can exist in almost all habitats found in polar, tropical, and temperate regions. It can either exist in a symbiotic relationship with fungi in the form of lichen or it can survive independently as a free-living organism alone or in colonies. Trebouxia is the most common photobiont in extant lichens. It is a primary producer of marine, freshwater and terrestrial ecosystems. It uses carotenoids and chlorophyll a and b to harvest energy from the sun and provide nutrients to various animals and insects.
Cyanobionts are cyanobacteria that live in symbiosis with a wide range of organisms such as terrestrial or aquatic plants; as well as, algal and fungal species. They can reside within extracellular or intracellular structures of the host. In order for a cyanobacterium to successfully form a symbiotic relationship, it must be able to exchange signals with the host, overcome defense mounted by the host, be capable of hormogonia formation, chemotaxis, heterocyst formation, as well as possess adequate resilience to reside in host tissue which may present extreme conditions, such as low oxygen levels, and/or acidic mucilage. The most well-known plant-associated cyanobionts belong to the genus Nostoc. With the ability to differentiate into several cell types that have various functions, members of the genus Nostoc have the morphological plasticity, flexibility and adaptability to adjust to a wide range of environmental conditions, contributing to its high capacity to form symbiotic relationships with other organisms. Several cyanobionts involved with fungi and marine organisms also belong to the genera Richelia, Calothrix, Synechocystis, Aphanocapsa and Anabaena, as well as the species Oscillatoria spongeliae. Although there are many documented symbioses between cyanobacteria and marine organisms, little is known about the nature of many of these symbioses. The possibility of discovering more novel symbiotic relationships is apparent from preliminary microscopic observations.
The Acharius Medal is awarded by the International Association for Lichenology (IAL) for lifetime achievement in lichenology. The organization resolved at its 1990 meeting that it would simultaneously honor professional achievement and commemorate Erik Acharius by presenting a medal in his name.
An autotroph or primary producer is an organism that produces complex organic compounds using carbon from simple substances such as carbon dioxide, generally using energy from light (photosynthesis) or inorganic chemical reactions (chemosynthesis). They convert an abiotic source of energy into energy stored in organic compounds, which can be used by other organisms. Autotrophs do not need a living source of carbon or energy and are the producers in a food chain, such as plants on land or algae in water. Autotrophs can reduce carbon dioxide to make organic compounds for biosynthesis and as stored chemical fuel. Most autotrophs use water as the reducing agent, but some can use other hydrogen compounds such as hydrogen sulfide.
Placopsis perrugosa is a saxicolous (rock-dwelling), placodioid lichen in the family Trapeliaceae. It was formally described as a new species in 1867 by Finnish lichenologist William Nylander, originally as a member of the genus Lecanora.
Peter James de Lange is a New Zealand botanist.
Elke Mackenzie, born Ivan Mackenzie Lamb, was a British polar explorer and botanist who specialised in the field of lichenology.
Ana María Crespo de las Casas is a Spanish lichenologist noted for studying the phytosociology, taxonomy and floristics of Mediterranean lichens. She was awarded the 2012 Acharius Medal from the International Association for Lichenology for lifetime achievements in lichenology, and the genera Crespoa, Cresponea and Cresporhaphis were named in her honor.
Otto Ludwig Lange was a German botanist and lichenologist. The focus of his scientific work was on the ecophysiology of wild and cultivated plants as well as lichens. He investigated heat, frost and drought resistance of lichens, bryophytes and vascular plants growing under extreme environmental conditions.
David John Galloway, FRSNZ was a biochemist, botanist, and lichenologist.
Thomas Hawkes Nash III is an American lichenologist. His research is about the biology and ecology of lichens, and the effects of air pollution on plants and lichens. He is known as an authority on the family Parmeliaceae. During his long career at the Arizona State University, he helped develop the lichen herbarium into a world-class collection with over 100,000 specimens representing more than 5000 species. In 2010, the year of his retirement, he was awarded the Acharius Medal for lifetime achievements in lichenology, and the following year had a Festschrift published in his honor.
Pulchrocladia retipora, most commonly known as the coral lichen, is a species of fruticose lichen in the family Cladoniaceae. It occurs in Australasia and New Caledonia where it grows in coastal and alpine heathlands. The lichen features coral-like branches and subbranches with numerous netlike perforations. It is known by multiple names, with some sources referring to it by its synonym Cladia retipora, or the common name lace lichen.
Mastodia is a genus of lichen-forming fungi in the family Verrucariaceae. It has six species. The genus was circumscribed in 1847 by Joseph Dalton Hooker and William Henry Harvey. The type species, Mastodia tessellata, is a bipolar, coastal lichen. It forms a symbiotic association with the macroscopic genus Prasiola; this is the only known lichen symbiosis involving a foliose green alga. Studies suggest that throughout its geographic range, the lichen comprises two fungal species and three algal lineages that associate.
References
- ↑ Green, T G A; Smith, D C (1974). "Lichen physiology 14. Differences between lichen algae in symbiosis and in isolation". New Phytologist. 73 (4): 753–766. doi:10.1111/j.1469-8137.1974.tb01303.x.
- 1 2 3 "Acharius Medallists Thomas George Allan Green". International Association for Lichenology. Retrieved 6 September 2022.
- ↑ "The Queen's Birthday Honours List 2013". Department of the Prime Minister and Cabinet, New Zealand - Te tari o te pirimia me te komiti matua. Retrieved 6 September 2022.
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