Lichenology is the branch of

mycology Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans, including as a source for tinder, traditional medicine, food, and entheogens, as ...

that studies the

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...

s made up of an intimate symbiotic association of a microscopic

alga Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mi ...

(or a

cyanobacterium Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blue ...

) with a filamentous

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

. Study of lichens draws knowledge from several disciplines:

phycology Phycology () is the scientific study of algae. Also known as algology, phycology is a branch of life science. Algae are important as primary producers in aquatic ecosystems. Most algae are eukaryotic, photosynthetic organisms that live in a w ...

microbiology Microbiology () is the scientific study of microorganisms, those being unicellular (single cell), multicellular (cell colony), or acellular (lacking cells). Microbiology encompasses numerous sub-disciplines including virology, bacteriology, prot ...

and

botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...

. Scholars of lichenology are known as

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. Study of lichens draws knowledge from several ...

History

The beginnings

Lichens as a group have received less attention in classical treatises on botany than other groups although the relationship between humans and some species has been documented from early times. Several species have appeared in the works of

Dioscorides Pedanius Dioscorides ( grc-gre, Πεδάνιος Διοσκουρίδης, ; 40–90 AD), “the father of pharmacognosy”, was a Greek physician, pharmacologist, botanist, and author of ''De materia medica'' (, On Medical Material) —a 5-vol ...

Pliny the Elder Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, naturalist and natural philosopher, and naval and army commander of the early Roman Empire, and a friend of the emperor Vespasian. He wrote the encyclopedic '' ...

and

Theophrastus Theophrastus (; grc-gre, Θεόφραστος ; c. 371c. 287 BC), a Greek philosopher and the successor to Aristotle in the Peripatetic school. He was a native of Eresos in Lesbos.Gavin Hardy and Laurence Totelin, ''Ancient Botany'', Routledge ...

although the studies are not very deep. During the first centuries of the modern age they were usually put forward as examples of

spontaneous generation Spontaneous generation is a superseded scientific theory that held that living creatures could arise from nonliving matter and that such processes were commonplace and regular. It was hypothesized that certain forms, such as fleas, could arise fr ...

and their reproductive mechanisms were totally ignored. For centuries naturalists had included lichens in diverse groups until in the early 18th century a French researcher

Joseph Pitton de Tournefort Joseph Pitton de Tournefort (5 June 165628 December 1708) was a French botanist, notable as the first to make a clear definition of the concept of genus for plants. Botanist Charles Plumier was his pupil and accompanied him on his voyages. Lif ...

in his ''Institutiones Rei Herbariae'' grouped them into their own genus. He adopted the Latin term lichen, which had already been used by Pliny who had imported it from Theophrastus but up until then this term had not been widely employed. The original meaning of the Greek word λειχήν (leichen) was moss that in its turn derives from the Greek verb λείχω (liekho) to suck because of the great ability of these organisms to absorb water. In its original use the term signified

mosses Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) ''sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and horn ...

liverworts The Marchantiophyta () are a division of non-vascular land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of ge ...

as well as

lichens A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among hypha, filaments of multiple fungus, fungi species in a mutualism (biology), mutualistic relationship.Dillenius Johann Jacob Dillen Dillenius (1684 – 2 April 1747) was a German botanist. He is known for his ''Hortus Elthamensis'' ("Eltham Garden") on the rare plants around Eltham, London, and for his ''Historia muscorum'' ("History of Mosses"), a natur ...

in his ''Historia Muscorum'' made the first division of the group created by Tournefort separating the sub-families

Usnea ''Usnea'' is a genus of mostly pale grayish-green fruticose lichens that grow like leafless mini-shrubs or tassels anchored on bark or twigs.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, The genus is in the f ...

, Coralloides and

Lichens A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among hypha, filaments of multiple fungus, fungi species in a mutualism (biology), mutualistic relationship.thallus Thallus (plural: thalli), from Latinized Greek (), 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 wer ...

. After the revolution in

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

brought in by

Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...

and his new system of classification lichens are retained in the

Plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...

Kingdom forming a single group

Lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.thallus Thallus (plural: thalli), from Latinized Greek (), 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 wer ...

. The

of lichens was first intensively investigated by the

Swedish Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by ...

botanist

Erik Acharius Erik Acharius (10 October 1757 – 14 August 1819) 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. Life Acharius was born in ...

(1757–1819), who is therefore sometimes named the "father of lichenology". Acharius was a student of

Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...

. Some of his more important works on the subject, which marked the beginning of lichenology as a discipline, are: * ''Lichenographiae Suecia prodromus'' (1798) * ''Methodus lichenum'' (1803) * ''Lichenographia universalis'' (1810) * ''Synopsis methodica lichenum'' (1814) Flechte auf Fels

Later lichenologists include the American scientists

Vernon Ahmadjian Vernon Ahmadjian (May 19, 1930 - March 13, 2012) 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. Car ...

and

Edward Tuckerman Edward Tuckerman (December 7, 1817 in Boston, Massachusetts – March 15, 1886) was an American botanist and professor who made significant contributions to the study of lichens and other alpine plants. He was a founding member of the Natura ...

and the

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

evolutionary biologist Evolutionary biology is the subfield of biology that studies the evolutionary processes (natural selection, common descent, speciation) that produced the diversity of life on Earth. It is also defined as the study of the history of life for ...

Konstantin Merezhkovsky, as well as amateurs such as Louisa Collings. Over the years research is shedding new light into the nature of these organisms still classified as plants. A controversial issue surrounding lichens since the early 19th century is their reproduction. In these years a group of researchers faithful to the tenets of Linnaeus considered that lichens reproduced sexually and had sexual reproductive organs, as in other plants, independent of whether asexual reproduction also occurred. Other researchers only considered asexual reproduction by means of

Propagules In biology, a propagule is any material that functions in propagating an organism to the next stage in its life cycle, such as by Biological dispersal, dispersal. The propagule is usually distinct in form from the parent organism. Propagules are ...

19th century

Against this background appeared the Swedish botanist

disciple of Linnaeus, who is today considered the father of lichenology, starting the taxonomy of lichens with his pioneering study of Swedish lichens in Lichenographiae Suecicae Prodromus of 1798 or in his Synopsis Methodica Lichenum, Sistens omnes hujus Ordinis Naturalis of 1814. These studies and classifications are the cornerstone of subsequent investigations. In these early years of structuring the new discipline various works of outstanding scientific importance appeared such as Lichenographia Europaea Reformata published in 1831 by

Elias Fries Elias Magnus Fries (15 August 1794 – 8 February 1878) was a Swedish mycologist and botanist. Career Fries was born at Femsjö (Hylte Municipality), Småland, the son of the pastor there. He attended school in Växjö. He acquired an ...

or Enumeratio Critico Lichenum Europaeorum 1850 by

Ludwig Schaerer Ludwig Emanuel Schaerer (11 June 1785 – 3 February 1853) was a Swiss pastor and lichenologist. Interested in natural history from a young age, Schaerer trained as a teacher and studied theology in Bern. During his career as a teacher, or ...

in Germany. Erik Acharius

But these works suffer from being superficial and mere lists of species without further physiological studies. It took until the middle of the 19th century for research to catch up using biochemical and physiological methods. In Germany and Johann Bayrhoffer, in France

Edmond Tulasne Louis René Étienne Tulasne, a.k.a. Edmond Tulasne (12 September 1815 – 22 December 1885) was a French botanist and mycologist born in Azay-le-Rideau. He originally studied law at Poitiers, but his interest later turned to botany. As a yo ...

and

Camille Montagne Jean Pierre François Camille Montagne (15 February 1784 – 5 December 1866) was a French military physician and botanist who specialized in the fields of bryology and mycology. He was born in the commune of Vaudoy in the department of Seine-et- ...

, in Russia Fedor Buhse, in England William Allport Leighton and in the United States

began to publish works of great scientific importance. Scientific publications settled many unknown facts about lichens. In the French publication Annales des Sciences Naturelles in an article of 1852 "Memorie pour servir a l'Histoire des Lichens Organographique et Physiologique" by

, the reproductive organs or apothecia of lichens was identified. These new discoveries were becoming increasingly contradictory for scientists. The

apothecium An ascocarp, or ascoma (), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascocarps are ...

reproductive organ being unique to

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

but absent in other

photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...

organisms. With improvements in

microscopy Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of micr ...

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

were identified in the lichen structure, which heightened the contradictions. At first the presence of algae was taken as being due to contamination due to collection of samples in damp conditions and they were not considered as being in a

symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

relation with the fungal part of the thallus. That the algae continued to multiply showed that they were not mere contaminants. It was

Anton de Bary Heinrich Anton de Bary (26 January 183119 January 1888) was a German surgeon, botanist, microbiologist, and mycologist (fungal systematics and physiology). He is considered a founding father of plant pathology (phytopathology) as well as the fou ...

a German

mycologist Mycology is the branch of biology concerned with the study of fungus, fungi, including their genetics, genetic and biochemistry, biochemical properties, their Taxonomy (biology), taxonomy and ethnomycology, their use to humans, including as a so ...

who specialised in

phytopathology Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomyc ...

who first suggested in 1865 that lichens were merely the result of parasitism of various fungi of the

ascomycetes 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 defi ...

group by

nostoc ''Nostoc'', also known as star jelly, troll’s butter, spit of moon, fallen star, witch's butter (not to be confused with the fungi commonly known as witches' butter), and witch’s jelly, is the most common genus of cyanobacteria found in vari ...

type algae and others. Successive studies such as those carried out by

Andrei Famintsyn Andrei Sergeyevich Famintsyn (russian: Андрей Серге́евич Фаминцын; June 29 ( O.S. June 17), 1835 in Moscow – December 8, 1918 in Petrograd) was a Russian botanist, public figure, and academician of the Petersburg Academy ...

and Baranetzky in 1867 showed no dependence of the algal component upon the lichen thallus and that the algal component could live independently of the thallus. It was in 1869 that

Simon Schwendener Simon Schwendener (10 February 1829 – 27 May 1919) was a Swiss botanist who was a native of Buchs in the Canton of St. Gallen. In 1856 he received his doctorate at the University of Zurich, where afterwards he was an assistant to Carl Wilhelm ...

demonstrated that all lichens were the result of fungal attack on the cells of algal cells and that all these algae also exist free in nature. This researcher was the first to recognise the dual nature of lichens as a result of the capture of the algal component by the fungal component. In 1873 Jean-Baptiste Edouard Bornet concluded form studying many different lichen species that the relationship between fungi and algae was purely

. It was also established that algae could associate with many different fungi to form different lichen

phenotypes In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological proper ...

20th century

In 1909 the Russian lichenologist

Konstantin Mereschkowski Konstantin Sergeevich Mereschkowski ( rus, Константи́н Серге́евич Мережко́вский, p=mʲɪrʲɪˈʂkofskʲɪj; – 9 January 1921) was a prominent Russian biologist and botanist, active mainly around Kazan, Tat ...

presented a research paper "The Theory of two Plasms as the basis of

Symbiogenesis Symbiogenesis (endosymbiotic theory, or serial endosymbiotic theory,) is the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms. The theory holds that mitochondria, plastids such as chloroplasts, and possi ...

, A new study on the Origin of Organisms", which aims to explain a new theory of Symbiogenesis by lichens and other organisms as evidenced by his earlier work "Nature and Origin of

Chromatophores Chromatophores are cells that produce color, of which many types are Biological pigment, pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and ...

in the Plant Kingdom". These new ideas can be studied today under the title of the Theory of

Endosymbiosis An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship. (The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within" ...

. Despite the above studies the dual nature of lichens remained no more than a theory until in 1939 the Swiss researcher Eugen A Thomas was able to reproduce in the laboratory the phenotype of the lichen '' Cladonia pyxidata'' by combining its two identified components. During the 20th century botany and mycology were still attempting to solve the two main problems surrounding lichens. On the one hand the definition of lichens and the relationship between the two symbionts and the taxonomic position of these organisms within the plant and fungal kingdoms. There appeared numerous renowned researchers within the field of lichenology such as

Henry Nicollon des Abbayes Henry Robert Nicollon des Abbayes (15 July 1898 – 21 May 1974) was a French botanist and lichenologist. He was the chair of the Botanical Department of the University of Rennes and an expert on the flora of Great Britain The flora of Great Brit ...

William Alfred Weber William Alfred Weber (November 16, 1918 – March 18, 2020) was an American botanist and lichenologist. He was Professor Emeritus at the University of Colorado at Boulder and former curator of the University of Colorado Museum of Natural History, ...

, Antonina Georgievna Borissova,

Irwin M. Brodo Irwin M. Brodo (born 1935) is an emeritus scientist at the Canadian Museum of Nature, in Ottawa, Ontario, Canada. He is an authority on the identification and biology of lichens. Irwin Brodo was honored in 1994 with an Acharius Medal presented to h ...

, and

George Albert Llano George Albert Llano (22 November 1911 – 9 February 2003), born Jorge Alberto Cecilio Perez y Llano, was a Cuban-born American polar explorer and botanist who specialized in the field of lichenology. He was an expert in the Umbilicariaceae. Ea ...

. Lichenology has found applications beyond

biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...

itself in the field of

geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...

in a technique known as

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. ...

where the age of an exposed surface can be found by studying the age of lichens growing on them. Age dating in this way can be absolute or relative because the growth of these organisms can be arrested under various conditions. The technique provides an average age of the older individual lichens providing a minimum age of the medium being studied. Lichenometry relies upon the fact that the maximum diameter of the largest thallus of an

epilithic Lithophytes are plants that grow in or on rocks. They can be classified as either epilithic (or epipetric) or endolithic; epilithic lithophytes grow on the surfaces of rocks, while endolithic lithophytes grow in the crevices of rocks (and are also ...

lichen growing on a substrate is directly proportional to the time from first exposure of the area to the environment as seen in studies by

Roland Beschel Roland Ernst Beschel (9 August 1928, Salzburg, Austria – 22 January 1971, Kingston, Ontario) was an Austrian botanist, lichenologist, professor, and herbarium director, known for his famous doctoral thesis and subsequent research on lichenometry. ...

in 1950 and is especially useful in areas exposed for less than 1000 years. Growth is greatest in the first 20 to 100 years with 15–50 mm growth per year and less in the following years with average growth of 2–4 mm per year. The difficulty of giving a definition applicable to every known lichen has been debated since lichenologists first recognised the dual nature of lichens. In 1982 the

International Association for Lichenology The International Association for Lichenology (IAL) is an organisation that encourages the understanding of lichens and lichenology, and promotes their study and conservation worldwide. It unites lichenologists across the globe, as well as national ...

convened a meeting to adopt a single definition of lichen drawing on the proposals of a committee. The chairman of this committee was the renowned researcher

. The definition finally adopted was that lichen could be considered as the association between a fungus and a photosynthetic symbiont resulting in a thallus of specific structure.David L. Hawksworth (1989) "Interactions Fungus and Alga in Lichen Symbiosis liquenoides" ''Annals of the Botanical Garden of Madrid'' (46). Such a simple

a priori ("from the earlier") and ("from the later") are Latin phrases used in philosophy to distinguish types of knowledge, justification, or argument by their reliance on empirical evidence or experience. knowledge is independent from current ex ...

definition soon brought criticism from various lichenologists and there soon emerged reviews and suggestions for amendments. For example, David L. Hawksworth considered the definition imperfect because it is impossible to determine which one thallus is of a specific structure since thalli changed depending upon the substrate and conditions in which they developed. This researcher represents one of the main trends among lichenologists who consider it impossible to give a single definition to lichens since they are a unique type of organism. Today studies in lichenology are not restricted to the description and taxonomy of lichens but have application in various scientific fields. Especially important are studies on

environmental quality "Environmental Quality" is a set of properties and characteristics of the environment, either generalized or local, as they impinge on human beings and other organisms. It is a measure of the condition of an environment relative to the requirements ...

that are made through the interaction of lichens with their environment. Lichen is extremely sensitive to various air pollutants, especially to

sulphur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic activ ...

, which causes

acid rain Acid rain is rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). Most water, including drinking water, has a neutral pH that exists between 6.5 and 8.5, but acid ...

and prevents water absorption. Merezhkovsky K S

Lichens in pharmacology

Although several species of lichen have been used in

traditional medicine Traditional medicine (also known as indigenous medicine or folk medicine) comprises medical aspects of traditional knowledge that developed over generations within the folk beliefs of various societies, including indigenous peoples, before the ...

it was not until the early 20th century that modern science became interested in them. The discovery of various substances with

antibacterial An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...

action in lichen thalli was essential for scientists to become aware of the possible importance of these organisms to

medicine Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pract ...

. From the 1940s there appeared various works by the noted

microbiologist A microbiologist (from Ancient Greek, Greek ) is a scientist who studies microscopic life forms and processes. This includes study of the growth, interactions and characteristics of Microorganism, microscopic organisms such as bacteria, algae, f ...

Rufus Paul Burkholder who demonstrated antibacterial action of lichens of the genus ''

'' against ''

Bacillus subtilis ''Bacillus subtilis'', known also as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants, humans and marine sponges. As a member of the genus ''Bacillu ...

'' and ''

Sarcina lutea The ''sarcina'' was the marching pack carried by Roman legionaries, the heavy infantry of the Roman legions. Most of a legionary's equipment other than his arms and armour would, in early times, have been consigned to a baggage train and b ...

''. Studies showed that the substance that inhibited growth of bacteria was

usnic acid Usnic acid is a naturally occurring dibenzofuran derivative found in several lichen species with the formula C18H16O7. It was first isolated by German scientist W. Knop in 1844 and first synthesized between 1933-1937 by Curd and Robertson. Usnic a ...

. Something similar occurred with the substance Ramelina synthesised by the lichen '' Ramalina reticulata'', nevertheless, these substances proved ineffective against

Gram negative bacteria Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

such as ''

Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...

'' and ''

Pseudomonas ''Pseudomonas'' is a genus of Gram-negative, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 described species. The members of the genus demonstrate a great deal of metabolic diversity and consequently are able ...

''. With these investigations the number of antibacterial substances and possible drug targets known to be produced by lichens increased

ergosterol Ergosterol (ergosta-5,7,22-trien-3β-ol) is a sterol found in cell membranes of fungi and protozoa, serving many of the same functions that cholesterol serves in animal cells. Because many fungi and protozoa cannot survive without ergosterol, the ...

etc. Interest in the potential of substances synthesised by lichens increased with the end of

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

along with the growing interest in all

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...

substances. In 1947 antibacterial action was identified in extracts of '' Cetraria islandica'' and the compounds identified as responsible for bacterial inhibition were shown to be d-protolichosteric acid and d-1-usnic acid. Further investigations have identified novel antibacterial substances, Alectosarmentin or

Atranorin Atranorin is a chemical substance produced by some species of lichen. It is a secondary metabolite belonging to a group of compounds known as depsides. Atranorin has analgesic, anti-inflammatory, antibacterial, antifungal, cytotoxic, antioxidant, ...

. Antibacterial action of substances produced by lichens is related to their ability to disrupt bacterial

proteins Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

with a subsequent loss of bacterial

metabolic Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

capacity. This is possible due to the action of lichen

phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it req ...

ics such as

derivatives. From the 1950s the lichen product

was the object of most

antitumour Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemotherap ...

research. These studies revealed some

in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology an ...

antitumour activity by substances identified in two common lichens ''

Peltigera leucophlebia ''Peltigera leucophlebia'' is a lichenized fungus in the family Peltigeraceae. It is commonly called ruffled freckled pelt. This and other species in the genus contain a green algae in the genus '' Coccomyxa'' and also cyanobacteria in the genu ...

'' and ''

Collema flaccidum ''Collema flaccidum'' is a species of lichen belonging to the family Collemataceae. References Peltigerales Lichen species Lichens described in 1795 Taxa named by Erik Acharius {{Peltigerales-stub ...

''. Recent work in the field of applied

biochemistry Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and ...

has shown some antiviral activity with some lichen substances. In 1989 K Hirabayashi presented his investigations on inhibitory lichen polysaccharides in

HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...

infection.

Bibliography

*"Protocols in Lichenology: Culturing, Biochemistry, Ecophysiology and Use in Biomonitoring" (Springer Lab Manuals, Kraner, Ilse, Beckett, Richard and Varma, Ajit (28 Nov 2001) *''Lichenology in the British Isles, 1568–1975: An Historical and Biographical Survey'', D. L. Hawksworth and M. R. D. Seaward (Dec 1977) *"Lichenology: Progress and Problems" (Special Volumes/Systematics Association) Denis Hunter Brown et al. (10 May 1976) *''Lichenology in Indian Subcontinent'', Dharani Dhar Awasthi (1 Jan 2000) *''Lichenology in Indian Subcontinent 1966–1977'', Ajay Singh (1980) *''CRC Handbook of Lichenology'', Volume II: v.2, Margalith Galun (30 Sep 1988) *''A Textbook of General Lichenology'', Albert Schneider (24 May 2013) *''Horizons in Lichenology'' D. H. Dalby (1988) *''Bibliography of Irish Lichenology'', M. E. Mitchell (Nov 1972) *''Diccionario de Liquenologia/Dictionary of Lichenology'', Kenneth Allen Hornak (1998) *"Progress and Problems in Lichenology in the Eighties: Proceedings" (''Bibliotheca Lichenologica''), Elisabeth Peveling (1987) *''A Textbook of General Lichenology with Descriptions and Figures of the Genera Occurring in the North Eastern United States'', Albert Schneider (Mar 2010) *''The Present Status and Potentialities of the Lichenology in China'', Liu Hua Jie (1 Jan 2000) *''Lichens to Biomonitor the Environment'', Shukla, D. K. Vertika, Upreti and Bajpai, Rajesh (Aug 2013) *''Lichenology and Bryology in the Galapagos Islands with Checklists of the Lichens and Bryophytes thus far Reported'', William A. Weber (1966) *''Flechten Follmann: Contributions to Lichenology in Honour of Gerhard Follmann'', Gerhard Follmann, F. J. A. Daniels, Margot Schultz and Jorge Peine (1995) *''Environmental Lichenology: Biomonitoring Trace Element Air Pollution'', Joyce E. Sloof (1993) *''The Journal of the Hattori Botanical Laboratory: Devoted to Bryology and Lichenology'', Zennosuke Iwatsuki (1983) *''Contemporary Lichenology and Lichens of Western Oregon'', W. Clayton Fraser (1968) *''Irish Lichenology 1858–1880: Selected Letters of Isaac Carroll, Theobald Jones, Charles Larbalestier'' (1996) *''Lichens from West of Hudson's Bay'' (''Lichens of Arctic America'' Vol. 1), John W. Thompson (1953) *''Les Lichens - Morphologie, Biologie, Systematique'', Fernand Moreau (1927) *"Eric Acharius and his Influence on English Lichenology" (''Botany Bulletins''), David J. Galloway (Jul 1988) *"Lichenographia Thompsoniana: North American Lichenology in Honour of John W. Thompson", M. G. Gleen (May 1998) *"Monitoring with Lichens-Proceedings of the NATO Advanced Research Workshop", Nimis, Pier Luigi, Scheidegger, Christoph and Wolseley, Patricia (Dec 2001) *''Contributions to Lichenology: In Honour of A. Henssen'', H. M. Jahns and A. Henssen (1990) *''Studies in Lichenology with Emphasis on Chemotaxonomy, Geography and Phytochemistry'': Festschrift Christian Leuckert, Johannes Gunther Knoph, Kunigunda Schrufer and Harry J. M. Sipman (1995) *''Swedish Lichenology: Dedicated to Roland Moberg'', Jan Erik Mattsson, Mats Wedin and Inga Hedberg (Sep 1999) *''Index of Collectors in Knowles the Lichens of Ireland (1929) and Porter's Supplement: with a Conspectus of Lichen'', M. E. Mitchell, Matilda C. Knowles and Lilian Porter (1998) *''Biodeterioration of Stone Surfaces: Lichens and Biofilms as Weathering Agents of Rocks and Cultural Heritage'', Larry St. Clair and Mark Seaward (Oct 2011) *''The Lichen Symbiosis'', Vernon Ahmadjian (Aug 1993) *''Lichen Biology'', Thomas H. Nash (Jan 2008) *''Fortschritte der Chemie organischer Naturstoffe/ Progress in the Chemistry of Organic Natural Products'', S. Hunek (Oct 2013)

Notable lichenologists

Lichen collections

British Lichen Society The British Lichen Society (BLS) was founded in 1958 with the objective of promoting the study and conservation of lichen. Although the society was founded in London, UK, it is also of relevance to lichens worldwide. It has been a registered ch ...

Botanische Staatssammlung München The Botanische Staatssammlung München is a notable herbarium and scientific center maintained by thStaatliche Naturwissenschaftliche Sammlungen Bayerns Its building is located within the Botanischer Garten München-Nymphenburg area at Menzinger ...

* Canadian Museum of Nature *

Centraalbureau voor Schimmelcultures The ''Westerdijk Institute'', or Westerdijk Fungal Biodiversity Institute, is part of the Royal Netherlands Academy of Arts and Sciences. The institute was renamed on 10 February 2017, after Johanna Westerdijk, the first female professor in the N ...

National Botanical Research Institute The National Botanical Research Institute (NBRI) is a research institute of the Council of Scientific and Industrial Research (CSIR) located in Lucknow, Uttar Pradesh, India. It is engaged in the field of taxonomy and modern biology. History Ori ...

(CSIR), India *

Iowa State University Iowa State University of Science and Technology (Iowa State University, Iowa State, or ISU) is a public land-grant research university in Ames, Iowa. Founded in 1858 as the Iowa Agricultural College and Model Farm, Iowa State became one of the n ...

, Ada Hayden Herbarium,

Ames, Iowa Ames () is a city in Story County, Iowa, United States, located approximately north of Des Moines in central Iowa. It is best known as the home of Iowa State University (ISU), with leading agriculture, design, engineering, and veterinary medici ...

National Museum Cardiff National Museum Cardiff ( cy, Amgueddfa Genedlaethol Caerdydd) is a museum and art gallery in Cardiff, Wales. The museum is part of the wider network of Amgueddfa Cymru – National Museum Wales. Entry is kept free by a grant from the Welsh Go ...

Natural History Museum, London The Natural History Museum in London is a museum that exhibits a vast range of specimens from various segments of natural history. It is one of three major museums on Exhibition Road in South Kensington, the others being the Science Museum an ...

New York Botanical Garden The New York Botanical Garden (NYBG) is a botanical garden at Bronx Park in the Bronx, New York City. Established in 1891, it is located on a site that contains a landscape with over one million living plants; the Enid A. Haupt Conservatory, ...

Royal Botanic Garden, Edinburgh The Royal Botanic Garden Edinburgh (RBGE) is a scientific centre for the study of plants, their diversity and conservation, as well as a popular tourist attraction. Founded in 1670 as a physic garden to grow medicinal plants, today it occupies ...

Royal Botanic Gardens, Kew Royal Botanic Gardens, Kew is a non-departmental public body in the United Kingdom sponsored by the Department for Environment, Food and Rural Affairs. An internationally important botanical research and education institution, it employs 1,100 ...

, London *

University of Michigan Herbarium The University of Michigan Herbarium is the herbarium of the University of Michigan in Ann Arbor, Michigan, in the United States. One of the most-extensive botanical collections in the world, the herbarium has some 1.7 million specimens of vascu ...

Ann Arbor, Michigan Ann Arbor is a city in the U.S. state of Michigan and the county seat of Washtenaw County, Michigan, Washtenaw County. The 2020 United States census, 2020 census recorded its population to be 123,851. It is the principal city of the Ann Arbor ...

Ulster Museum The Ulster Museum, located in the Botanic Gardens in Belfast, has around 8,000 square metres (90,000 sq. ft.) of public display space, featuring material from the collections of fine art and applied art, archaeology, ethnography, treasure ...

, Belfast

Footnotes

References

External links

American Bryological and Lichenological SocietyBelgium, Luxembourg and Northern France, Lichens ofBritish Lichen SocietyCentral European Bryological and Lichenological Society (Ger)Czech Bryological and Lichenological Society (Cze)Guide to using a Lichen-Based Index to Assess Nitrogen Air Quality
* ttp://www.lichenology.org/ International Association for Lichenologybr>Irish Lichens

Italian Lichenological Society (Ita)Japanese Lichenological Society (Eng)Lichenological Resources (Rus)Lichenland Oregon State UniversityLichens of Ireland Project

Microscopy of Lichens (Ger)Netherlands Bryological and Lichenological Society (nl)National Biodiversity GatewayNordic Lichen Society (Eng)North American LichensPaleo-Lichenology (Ger)Scottish LichensSwedish Lichens Lief & Anita StridvallTropical Lichens
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