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.
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.
Peltigera is a genus of approximately 100 species of foliose lichens in the family Peltigeraceae. Commonly known as the dog or pelt lichens, species of Peltigera are often terricolous, but can also occur on moss, trees, rocks, and many other substrates in many parts of the world.
Lecanora is a genus of lichen commonly called rim lichens. Lichens in the genus Squamarina are also called rim lichens. Members of the genus have roughly circular fruiting discs (apothecia) with rims that have photosynthetic tissue similar to that of the nonfruiting part of the lichen body (thallus). Other lichens with apothecia having margins made of thallus-like tissue are called lecanorine.
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.
Hypogymnia is a genus of foliose lichens in the family Parmeliaceae. They are commonly known as tube lichens, bone lichens, or pillow lichens. Most species lack rhizines that are otherwise common in members of the Parmeliaceae, and have swollen lobes that are usually hollow. The lichens usually grow on the bark and wood of coniferous trees.
Myelochroa is a genus of foliose lichens in the family Parmeliaceae. They are commonly known as axil-bristle lichens. It was created in 1987 to contain species formerly placed in genus Parmelina that had a yellow-orange medulla due to the presence of secalonic acids. Characteristics of the genus include tightly attached thalli with narrow lobes, cilia on the axils, and a rhizinate black lower surface. Chemical characteristics are the production of zeorin and related triterpenoids in the medulla. Myelochroa contains about 30 species, most of which grow on bark. The genus has centres of distribution in Asia and North America.
Flavoparmelia is a genus of foliose lichens in the family Parmeliaceae. Because of their appearance, they are commonly known as greenshield lichens. The widely distributed genus contains 32 species. It was circumscribed by American lichenologist Mason Hale in 1986 to contain 17 former Pseudoparmelia species with broad lobes, usnic acid in the cortex, and isolichenan in the cell walls.
Pseudocyphellaria is a genus of large, leafy lichens that are sometimes referred to as "specklebelly" lichens. The genus has a widespread distribution, especially in south temperate regions, and contains about 170 species. They resemble Lobaria, except that most species of Pseudocyphellaria have conspicuous pseudocyphellae on their lower surface, a characteristic that was once considered unique to this genus. Some species contain pulvinic acid-related pigments; in these species the soredia and pseudocyphellae can be bright yellow.
Imshaugia is a genus of seven species of foliose lichens in the family Parmeliaceae. They are commonly known as starburst lichens.
Esslingeriana is a fungal genus in the family Parmeliaceae. The genus is monotypic, containing the single foliose lichen species Esslingeriana idahoensis, commonly known as the tinted rag lichen. It is found in northwestern North America.
Pilophorus acicularis, commonly known as the nail lichen or the devil's matchstick lichen, is a species of matchstick lichen in the family Cladoniaceae.
Foliose lichen is one of the morphological classes 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.
Dendriscocaulon is a taxonomic name that has been used for a genus of fruticose lichen with a cyanobacteria as the photobiont partner of the fungus. Dendriscocaulon is considered a taxonomic synonym of the genus Sticta, a foliose lichen, which generally has a green alga as the photobiont partner. Lichens that have been called Dendriscocaulon or Sticta involve the same fungal species. They show dramatically different morphology, may grow side-by-side, and mixed forms exist where different algae are growing within different portions of the same fungal thallus. The biochemistry of the two forms is very different, but the DNA sequences from the fungus and the photobiont can be distinguished using different primers for DNA sequencing.
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.
Heppia is a genus of olive, brownish, gray, or blackish squamulose, crustose, or peltate like lichens. Heppia was once the type genus of the family Heppiaceae, but that family was folded into synonymy with Lichinaceae.
Lobothallia is a genus of lichens in the family Megasporaceae. Species in the genus have foliose thalli that become crustose areolate in the center with age, and grow on calcareous to siliceous rocks. The crustose part of the body may keep its lower cortex, though not always. Dark brown to black apothecia may be sunken into the surface of the thallus, as indicated in the common name puffed sunken disk lichen. Members grow to 3–5 cm (1.2–2.0 in) or more radiating lobes (placoidioid). The photobiont is green alga from the genus Trebouxia. The genus is represented in Eurasia, Asia, North Africa, Central America, western North America, and Australia.
Parmotrema rampoddense, commonly known as the long-whiskered ruffle lichen, is a species of foliose lichen in the family Parmeliaceae. It is widely distributed in tropical regions and grows on the bark of oak and palm trees.
Melanohalea subolivacea, commonly known as the brown-eyed camouflage lichen, is a species of foliose lichen in the family Parmeliaceae.
Nephroma resupinatum, commonly known as the pimpled kidney lichen, is a species of foliose lichen in the family Peltigeraceae. It was first described by Carl Linnaeus in his 1753 work Species Plantarum as Lichen resupinatus. Erik Acharius transferred it to the genus Nephroma in 1810.
