A lichen is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. Lichens are important actors in nutrient cycling and act as producers which many higher trophic feeders feed on, such as reindeer, gastropods, nematodes, mites, and springtails. 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.
Ethnolichenology is the study of the relationship between lichens and people. Lichens have and are being used for many different purposes by human cultures across the world. The most common human use of lichens is for dye, but they have also been used for medicine, food and other purposes.
Bryoria fremontii is a dark brown, horsehair lichen that grows hanging from trees in western North America, and northern Europe and Asia. It grows abundantly in some areas, and is an important traditional food for a few First Nations in North America.
Vulpinic acid is a natural product first found in and important in the symbiosis underlying the biology of lichens. It is a simple methyl ester derivative of its parent compound, pulvinic acid, and a close relative of pulvinone, both of which derive from aromatic amino acids such as phenylalanine via secondary metabolism. The roles of vulpinic acid are not fully established, but may include properties that make it an antifeedant for herbivores. The compound is relatively toxic to mammals.
Chrysothrix candelaris, commonly known as the mustard powder lichen or gold dust lichen, is a species of leprose (powdery) lichen in the family Chrysothricaceae. It typically grows on tree bark, although it has also been recorded growing on rock. It does not show ascocarps or other reproductive structures, belonging to the group commonly known as the 'Fungi or lichens imperfecti' in the UK.
Rusavskia elegans, commonly known as the elegant sunburst lichen, is a lichenized species of fungus in the genus Rusavskia, family Teloschistaceae. Recognized by its bright orange or red pigmentation, this species grows on rocks, often near bird or rodent perches. It has a circumpolar and alpine distribution. It was one of the first lichens to be used for the rock-face dating method known as lichenometry.
Pseudephebe is a genus of fruticose lichens in the family Parmeliaceae. It contains three species that grow on rocks.
Vulpicida is a genus of lichenized fungi in the family Parmeliaceae. Circumscribed in 1993 to contain species formerly placed in Cetraria, the genus is widespread in Arctic to northern temperate regions, and contains six species. The genus is characterized by the presence of the secondary metabolites pulvinic acid and vulpinic acid, compounds that when combined with usnic acid, give the species their characteristic yellow and green colors.
Lobaria oregana, also known as lettuce lichen and as Oregon lungwort, is a species of foliose lichen occurring in North American old-growth forests, such as the Hoh Rainforest in Washington state. Taking its common name from its lettuce-like appearance, the lichen grows in the tree canopy but falls to the forest floor, where it is consumed by deer, elk, and other animals. The species was first described by American botanist Edward Tuckerman in 1874 as Sticta oregana, and later (1889) transferred to the genus Lobaria by Swiss lichen specialist Johannes Müller Argoviensis. Via cyanobacteria, it fixes nitrogen from the air, which then enters the local ecosystem when eaten or when absorbed by rootlets which the host trees extend from their own bark into the lichen.
Collema tenax is a species of lichen known by the common names jelly lichen, black lichen, and desert lichen. It occurs in Arctic and temperate regions in the Northern Hemisphere. It is very common in North America, and it is present in Europe, Asia, and Africa. It is the most widely distributed Collema.
Lecanora xanthoplumosella is a species of crustose lichen in the family Lecanoraceae. Known from Australia, it was described as new to science in 2011.
Lichens of the Sierra Nevada have been little studied. A lichen is a composite organism consisting of a fungus and a photosynthetic partner growing together in a symbiotic relationship.
A fruticose lichen is a form of lichen fungi that is characterized by a coral-like shrubby or bushy growth structure. It is formed from a symbiotic relationship of a photobiont such as green algae or less commonly cyanobacteria and one, two or more mycobionts. Fruticose lichens are not a monophyletic and holophyletic lineage, but is a form encountered in many classes. Fruticose lichens have a complex vegetation structure, and are characterized by an ascending, bushy or pendulous appearance. As with other lichens, many fruticose lichens can endure high degrees of desiccation. They grow slowly and often occur in habitats such as on tree barks, on rock surfaces and on soils in the Arctic and mountain regions.
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.
Niebla sorediata is a fruticose lichen that grows on rocks along the foggy Pacific Coast of North America, in the Channel Islands of California and on Guadalupe Island of Baja California. The epithet, sorediata, is in reference to the development of soredia (soredium).
Letharia columbiana is a common lichen in subalpine forests, particularly in the Pacific Northwest of the United States, and parts of Canada. It is in the family Parmeliaceae, and the genus Letharia. Its characteristics include a bright citron color, “brown-eyes”, and rounded, irregular branches. Though previously believed to lump together several lineages such as Letharia gracilis and others, there now exists more specific characteristics to identify the species. This lichen grows on the bark of conifers a couple inches tall. L. Columbiana’s cousin, Letharia vulpina (common name wolf lichen), has similar geographical distribution and morphological features, with the major difference being the “brown-eyes” of L. columbiana.
Candelaria concolor, commonly known as the candleflame lichen or the lemon lichen, is an ascomycete of the genus Candelaria. It is a small foliose lichen dispersed globally.
Pseudevernia consocians is a species of lichen in the family Parmeliaceae. It is found in both North America and Central America. Some characteristic features of Pseudevernia consocians are its well-developed, numerous isidia, relatively narrow lobes, and the presence of the lichen product lecanoric acid.
Cladonia lutescens is a species of fruticose lichen in the family Cladoniaceae. It occurs in high-altitude conditions of the Himalayas.
Teloschistes capensis, commonly known as the Cape hair lichen, is a species of fruticose lichen in the family Teloschistaceae. It is endemic to the Atlantic coast in Namibia and South Africa.
