A hypha is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium.
The Cladoniaceae are a family of lichen-forming fungi in the order Lecanorales, comprising about 560 species distributed amongst 18 genera. This family is one of the largest among lichen-forming fungi and is globally distributed, from Arctic tundra to tropical rainforests, favouring humid environments while being intolerant of arid conditions. Molecular phylogenetics has significantly advanced the understanding of their complex taxonomic history, revealing intricate evolutionary relationships and leading to a refined classification. Notable members include reindeer moss and cup lichens of the genus Cladonia, which consist of about 500 species and forms a significant part of the diet for large mammals in taiga and tundra ecosystems.
Physcia stellaris is a species of lichen. It is pale grey, but darker in the centre, and lacks isidia, lobules, soredia and pruina.It tests positive K+ yellow upper cortex with a 10% potassium hydroxide solution. In North America, it is known colloquially as the fringed rosette lichen.
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.
The Collemataceae are a family of mostly lichen-forming fungi in the order Peltigerales. The family contains twelve genera and about 325 species. The family has a widespread distribution.
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.
Arthonia is a genus of lichens in the family Arthoniaceae. It was circumscribed by Swedish botanist Erik Acharius in 1806.
Pseudephebe is a genus of fruticose lichens in the family Parmeliaceae. It contains three species that grow on rocks.
Xanthoparmelia is a genus of foliose lichens in the family Parmeliaceae. This genus of lichen is commonly found in the United States, South America, southern Africa, Europe, Australia, and New Zealand.
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.
Pseudocyphellae are structures in lichens that appear as tiny pores on the outer surface of the lichen. They are caused when there is a break in the cortex of the lichen, and the medullary hyphae extend to the surface. Pseudocyphellae are the same colour as the medulla of the lichen, which is generally white, but can be yellow in some species of Pseudocyphellaria and in Bryoria fremontii. The presence/absence, abundance, colour, and shape of pseudocyphellae can all be diagnostic features used to identify different species. They facilitate gas exchange through the surface of the lichen, and may provide an adaptive advantage in temperate environments.
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.
A foliose lichen is a lichen with flat, leaf-like lobes, which are generally not firmly bonded to the substrate on which it grows. It is one of the three most common growth forms of lichens. It typically has distinct upper and lower surfaces, each of which is usually covered with a cortex; some, however, lack a lower cortex. The photobiont layer lies just below the upper cortex. Where present, the lower cortex is usually dark, but occasionally white. Foliose lichens are attached to their substrate either by hyphae extending from the cortex or medulla, or by root-like structures called rhizines. The latter, which are found only in foliose lichens, come in a variety of shapes, the specifics of which can aid in species identification. Some foliose lichens attach only at a single stout peg called a holdfast, typically located near the lichen's centre. Lichens with this structure are called "umbilicate". In general, medium to large epiphytic foliose lichens are moderately sensitive to air pollution, while smaller or ground-dwelling foliose lichens are more tolerant. The term "foliose" derives from the Latin word foliosus, meaning "leafy".
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.
Lichen morphology describes the external appearance and structures of a lichen. These can vary considerably from species to species. Lichen growth forms are 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.
Symbiosis in lichens is the mutually beneficial symbiotic relationship of green algae and/or blue-green algae (cyanobacteria) living among filaments of a fungus, forming lichen.
The following outline provides an overview of and topical guide to lichens.
Parmotrema perforatum, commonly known as the perforated ruffle lichen, is a species of foliose lichen in the family Parmeliaceae. The lichen was first formally described as new species in 1787 by Nikolaus Joseph von Jacquin. It was transferred to the genus Parmotrema by Italian lichenologist Abramo Bartolommeo Massalongo in 1860. The lichen is characterized by its apothecia often having a perforated hole in the center. The genus Parmotrema has a naked (white) zone on the underside margin and often has long hair-like projections on the lobe edges called cilia; P. perforatum is no different. The thallus is gray and lacks the yellow-green tones that is seen in lichens with usnic acid. There are no asexual structures, but there are apothecia that have the characteristic hole in the center.
Normandina pulchella, commonly known as the elf-ear lichen or blue heart, is a species of squamulose lichen in the family Verrucariaceae. This cosmopolitan species is widely distributed across both hemispheres, where it thrives in moist microhabitats. It favours moss-covered deciduous trees and rocks, often colonising over mosses and bryophytes. It occasionally grows on bare bark and on other lichens. Distinctive features of N. pulchella include its bluish-green squamules (scales) with sharply raised margins, non-reactivity to standard chemical spot tests, and growth in humid habitats. Initially, Nannochloris normandinae, a green alga, was thought to be its photobiont. More recent studies, however, have revised this understanding, with Diplosphaera chodatii now recognised as the algal partner.
