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.
Lonicera japonica, known as Japanese honeysuckle and golden-and-silver honeysuckle, is a species of honeysuckle native to eastern Asia. It is often grown as an ornamental plant, but has become an invasive species in a number of countries. Japanese honeysuckle is used in traditional Chinese medicine.
Evernia prunastri, also known as oakmoss, is a species of lichen. It can be found in many mountainous temperate forests throughout the Northern Hemisphere. Oakmoss grows primarily on the trunk and branches of oak trees, but is also commonly found on the bark of other deciduous trees and conifers such as fir and pine. The thalli of oakmoss are short and bushy, and grow together on bark to form large clumps. Oakmoss thallus is flat and strap-like. They are also highly branched, resembling the form of antlers. The colour of oakmoss ranges from green to a greenish-white when dry, and dark olive-green to yellow-green when wet. The texture of the thalli is rough when dry and rubbery when wet. It is used extensively in modern perfumery.
Rutin, also called rutoside, quercetin-3-O-rutinoside and sophorin, is the glycoside combining the flavonol quercetin and the disaccharide rutinose. It is a citrus flavonoid found in a wide variety of plants including citrus.
Pseudevernia furfuracea, commonly known as tree moss, is a lichenized species of fungus that grows on the bark of firs and pines. The lichen is rather sensitive to air pollution, its presence usually indicating good air conditions in the growing place. The species has numerous human uses, including use in perfume, embalming and in medicine. Large amounts of tree moss is annually processed in France for the perfume industry.
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 acid was identified in many genera of lichens including Usnea, Cladonia, Hypotrachyna, Lecanora, Ramalina, Evernia, Parmelia and Alectoria. Although it is generally believed that usnic acid is exclusively restricted to lichens, in a few unconfirmed isolated cases the compound was found in kombucha tea and non-lichenized ascomycetes.
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.
Pseudevernia is a genus of foliose lichens in the family Parmeliaceae. The type species of the genus, Pseudevernia furfuracea, has substantial commercial value in the perfume industry.
A depside is a type of polyphenolic compound composed of two or more monocyclic aromatic units linked by an ester bond. Depsides are most often found in lichens, but have also been isolated from higher plants, including species of the Ericaceae, Lamiaceae, Papaveraceae and Myrtaceae.
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.
A xanthonoid is a chemical natural phenolic compound formed from the xanthone backbone. Many members of the Clusiaceae contain xanthonoids.
Lunularic acid is a dihydrostilbenoid found in the liverwort Lunularia cruciata and in the roots of Hydrangea macrophylla.
Conocephalum conicum, also known as the great scented liverwort or snakeskin liverwort, is a liverwort species in the genus Conocephalum. C. conicum is part of the Conocephalum conicum complex, which includes several cryptic species. The name C. conicum refers to the cone-shaped archegoniaphore, which bear sporangia.
Isolichenan, also known as isolichenin, is a cold-water-soluble α-glucan occurring in certain species of lichens. This lichen product was first isolated as a component of an extract of Iceland moss in 1813, along with lichenin. After further analysis and characterization of the individual components of the extract, isolichenan was named in 1881. It is the first α-glucan to be described from lichens. The presence of isolichenan in the cell walls is a defining characteristic in several genera of the lichen family Parmeliaceae. Although most prevalent in that family, it has also been isolated from members of the families Ramalinaceae, Stereocaulaceae, Roccellaceae, and Cladoniaceae. Experimental studies have shown that isolichenan is produced only when the two lichen components – fungus and alga – are growing together, not when grown separately. The biological function of isolichenan in the lichen thallus is unknown.
Garcinia pseudoguttifera, known as the mo'onia tree in its native range, is a species of flowering tree in the family Clusiaceae or Guttiferae.
Trapelia coarctata is a lichenised fungus in the family, Trapeliaceae.
Salazinic acid is a depsidone with a lactone ring. It is found in some lichens, and is especially prevalent in Parmotrema and Bulbothrix, where its presence or absence is often used to help classify species in those genera.
Lichexanthone is an organic compound in the structural class of chemicals known as xanthones. Lichexanthone was first isolated and identified by Japanese chemists from a species of leafy lichen in the 1940s. The compound is known to occur in many lichens, and it is important in the taxonomy of species in several genera, such as Pertusaria and Pyxine. More than a dozen lichen species have a variation of the word lichexanthone incorporated as part of their binomial name. The presence of lichexanthone in lichens causes them to fluoresce a greenish-yellow colour under long-wavelength UV light; this feature is used to help identify some species. Lichexanthone is also found in several plants, and some species of fungi that do not form lichens.
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.
Lichen products, also known as lichen substances, are organic compounds produced by a lichen. Specifically, they are secondary metabolites. Lichen products are represented in several different chemical classes, including terpenoids, orcinol derivatives, chromones, xanthones, depsides, and depsidones. Over 800 lichen products of known chemical structure have been reported in the scientific literature, and most of these compound are exclusively found in lichens. Examples of lichen products include usnic acid, atranorin, lichexanthone, salazinic acid, and isolichenan, an α-glucan. Many lichen products have biological activity, and research into these effects is ongoing.
