Parmelia is a genus of medium to large foliose (leafy) 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.
Psora is a genus of lichen-forming fungi in the family Psoraceae. Members of the genus are commonly called fishscale lichens. Lichens in the genus Psora generally have a squamulose thallus and anthraquinones in the hymenium. Photobiont partners of Psora lichens include members of the green algal genera Asterochloris, Chloroidium, Myrmecia, and Trebouxia.
Bacidia is a genus of lichen-forming fungi in the family Ramalinaceae. The genus was circumscribed by Giuseppe De Notaris in 1846.
Ramalina is a genus of greenish fruticose lichens that grow in the form of flattened, strap-like branches. Members of the genus are commonly called strap lichens or cartilage lichens. Apothecia are lecanorine.
Xylographa is a genus of lichenized fungi in the family Xylographaceae.
Acarospora is a genus of mostly lichen-forming 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.
Diploschistes is a genus of lichen-forming fungi in the family Graphidaceae. Commonly known as crater lichens, members of the genus are crustose lichens with a thick, cracked (areolate) body (thallus) with worldwide distribution. The fruiting part (apothecia) are immersed in the thick thallus so as to have the appearance of being small "craters". The widespread genus contains about 43 species.
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.
Leptogium is a genus of lichen-forming fungi in the family Collemataceae. It has about 110 species. Species formerly classified under Leptogium have since been divided among the genera Leptogium, Pseudoleptogium, and Scytinium. Leptogium lichens are predominantly found on tree bark or soil, often among mosses, and sometimes on rocks in moist environments.
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.
A cephalodium (pl. cephalodia) is a small gall-like structure found in some lichens. They occur only in lichens which contain both cyanobacterial and green algal partners. Cephalodia can occur within the tissues of the lichen, or on its upper or lower surface. Lichens with cephalodia can fix nitrogen, and may be an important contributor of nitrogen to the ecosystem.
Imshaugia is a genus of seven species of foliose lichens in the family Parmeliaceae. They are commonly known as starburst lichens.
Lichens are symbiotic organisms made up of multiple species: a fungus, one or more photobionts and sometimes a yeast. They are regularly grouped by their external appearance – a characteristic known as their growth form. This form, which is based on the appearance of vegetative part of the lichen, varies depending on the species and the environmental conditions it faces. Those who study lichens (lichenologists) have described a dozen of these forms: areolate, byssoid, calicioid, cladoniform, crustose, filamentous, foliose, fruticose, gelatinous, leprose, placoidioid and squamulose. Traditionally, crustose (flat), foliose (leafy) and fruticose (shrubby) are considered to be the three main forms. In addition to these more formalised, traditional growth types, there are a handful of informal types named for their resemblance to the lichens of specific genera. These include alectorioid, catapyrenioid, cetrarioid, hypogymnioid, parmelioid and usneoid.
Stereocaulon is a genus of lichens. Members of Stereocaulon are commonly called rock foam lichens. Photobiont partners of Stereocaulon include green algae from the genera Asterochloris, Chloroidium, and Vulcanochloris. Stereocaulon is difficult to ID to species, but there is a high diversity of species within the genus.
Orvo Vitikainen is a Finnish lichenologist. He entered the University of Helsinki in 1961, from where he obtained a Candidate of Philosophy degree in 1966, and a Licentiate of Philosophy in 1971. He later earned a Ph.D. from this institution in 1994, under the supervision of Teuvo Ahti. Between the years 1961 and 1981 he was a junior curator of cryptogams at the University of Helsinki Botanical Garden, and then from 1983 to 2004 he was the head of the lichen herbarium. Here he managed the internationally valuable collections of the early lichenologists Erik Acharius and William Nylander. He has collected thousands of specimens for the herbarium from various locations in Finland, but also internationally, including Sweden, Norway, Denmark, Russian Karelia, Scotland, Austria, Italy, Hungary, Croatia, Montenegro, Tanzania, Kenya, British Columbia, and Brazil. In 1992–1994, he was a scientist of the Finnish Academy in the Ahti research group.
Solorina crocea, commonly known as the orange chocolate chip lichen, is a species of terricolous (ground-dwelling) and foliose (leafy) lichen in the family Peltigeraceae. The lichen, which was first formally described by Carl Linnaeus in 1753, has an arctic–alpine and circumpolar distribution and occurs in Asia, Europe, North America, and New Zealand. It generally grows on the bare ground in sandy soils, often in moist soil near snow patches or seepage areas. Although several forms and varieties of the lichen have been proposed in its history, these are not considered to have any independent taxonomic significance.
Crocodia is a genus of foliose lichens in the family Peltigeraceae. It has eight species. The genus has a cosmopolitan distribution, although most species occur in temperate and tropical regions of the Southern Hemisphere. The main characteristics of the genus that separate it from its parent genus, Pseudocyphellaria, include a yellow medulla and yellow pseudocyphellae on the lower thallus surface.
Nephroma arcticum, the arctic kidney lichen, is a species of foliose (leafy), terricolous (ground-dwelling) lichen in the family Parmeliaceae. It has a yellowish-green thallus up to 8 cm (3 in) across made of large lobes, with a dark, tomentose lower surface. It is a tripartite lichen, consisting of a fungus and two photobiont partners: a species of nitrogen-fixing cyanobacteria, and a species of green alga. First described by Carl Linnaeus in 1753, it is one of only two Nephroma species in North America that use green algae as their primary photobiont.
