Usnea is a genus of mostly pale grayish-green fruticose lichens that grow like leafless mini-shrubs or tassels anchored on bark or twigs. The genus is in the family Parmeliaceae. It grows all over the world. Members of the genus are commonly called old man's beard, beard lichen, or beard moss.
Xanthoria parietina is a foliose lichen in the family Teloschistaceae. It has wide distribution, and many common names such as common orange lichen, yellow scale, maritime sunburst lichen and shore lichen. It can be found near the shore on rocks or walls, and also on inland rocks, walls, or tree bark. It was chosen as a model organism for genomic sequencing by the US Department of Energy Joint Genome Institute (JGI).
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.
Melanohalea is a genus of foliose lichens in the family Parmeliaceae. It contains 30 mostly Northern Hemisphere species that grow on bark or on wood. The genus is characterized by the presence of pseudocyphellae, usually on warts or on the tips of isidia, a non-pored epicortex and a medulla containing depsidones or lacking secondary compounds. Melanohalea was circumscribed in 2004 as a segregate of the morphologically similar genus Melanelia.
Punctelia is a genus of foliose lichens belonging to the large family Parmeliaceae. The genus, which contains about 50 species, was segregated from genus Parmelia in 1982. Characteristics that define Punctelia include the presence of hook-like to thread-like conidia, simple rhizines, and point-like pseudocyphellae. It is this last feature that is alluded to in the vernacular names speckled shield lichens or speckleback lichens.
Hildur Krog was a Norwegian botanist.
Józef Motyka was a Polish botanist and lichenologist.
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.
Usnea articulata, commonly known as the string-of-sausage lichen, is a pale greenish-grey, densely branched lichen with a prostrate or pendant growth form. It grows on bark, on branches and twigs, and is often unattached to a branch and merely draped over it. It grows up to 100 cm (40 in) in length.
Usnea trichodea, commonly known as bony beard lichen, is a pale straw-colored fruticose lichen with a pendant growth form. It grows on trees and is native to eastern North America.
Peter Wilfred James (1930–2014) was an English botanist and lichenologist. He was a pioneer in the study of lichens as environmental indicators, especially of atmospheric pollution.
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.
Brian John Coppins is a botanist and lichenologist, considered a world authority on crustose lichens and a leading expert on the genus Micarea.
Usnea florida is a species of beard lichen in the family Parmeliaceae. It was first described by Carl Linnaeus in his 1753 work Species Plantarum. German botanist Friedrich Heinrich Wiggers transferred it to the genus Usnea in 1780. It is considered a threatened or vulnerable species in several European countries.
Punctelia rudecta, commonly known as the rough speckled shield or the speckleback lichen, is a North American species of foliose lichen in the family Parmeliaceae. This species can be readily identified by the light color of the thallus underside, the relatively large lobes at the edges of the thallus, and the tiny white pores present on the top of the thallus that are characteristic of the genus Punctelia. The lichen is quite abundant and widespread in the eastern and southeastern United States, although it also occurs in Canada and northern Mexico, but is less common in these regions. The lichen usually grows on bark, and less commonly on shaded rocks. There are several lookalike Punctelia species; these can often be distinguished from P. rudecta by differences in distribution or in the nature of the reproductive structures present on the thallus.
Philippe Clerc is a Swiss lichenologist. A Festschrift was dedicated to him in 2020, on the occasion of his retirement from the Conservatory and Botanical Garden of the City of Geneva, where he worked from 1993 to 2020. Clerc is an authority on the beard lichens, and has had nearly 100 publications on this and other topics, such as the lichen flora of Switzerland.
Lepraria incana is a species of dust lichen in the family Stereocaulaceae. First described scientifically by Johann Jacob Dillenius in 1741, and then formally by Carl Linnaeus in 1753, it is the type species of the genus Lepraria. The thallus of this species is green to greyish-green, and powdery – as if made of tiny granules. These granules are soredia, which are asexual reproductive structures. Like most members of genus Lepraria, the lichen has few distinguishing features, lacking both a medulla and sexual reproductive structures (apothecia). Chemically, the lichen is characterised by the presence of the secondary chemicals known as divaricatic acid and zeorin.
Gowardia nigricans, commonly known as the gray hair lichen or gray witch's hair, is a species of fruticose lichen in the family Parmeliaceae.
Constictic acid is a chemical compound of the depsidone class. It was first isolated in 1968 from lichen of the genus Usnea. It has since been found in many other lichen genera including Menegazzia, Crespoa, and Xanthoparmelia.
Usnea lambii is a small species of fruticose lichen in the family Parmeliaceae. It was first formally described as a new species in 1954 by Henry Imshaug. It has a bipolar distribution, that is, it occurs at both of Earth's polar regions. It is also found at high elevations in Mount Rainier National Park in Washington state, where it was first discovered.
