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.
The Parmeliaceae is a large and diverse family of Lecanoromycetes. With over 2700 species in 71 genera, it is the largest family of lichen-forming fungi. The most speciose genera in the family are the well-known groups: Xanthoparmelia, Usnea, Parmotrema, and Hypotrachyna.
Dolichousnea longissima, commonly known by the names old man's beard or Methuselah's beard lichen, is a fruticose lichen in the family Parmeliaceae.
Pseudephebe is a genus of fruticose lichens in the family Parmeliaceae. It contains three species that grow on rocks.
Flavopunctelia is a genus of foliose lichens in the family Parmeliaceae. The genus contains species that are widespread in temperate and tropical areas. The genus is characterised by broad, yellow-green lobes, point-like (punctiform) pseudocyphellae on the thallus surface, and bifusiform conidia. All species contain usnic acid as a major secondary chemical in the cortex. Flavopunctelia was originally conceived as a subgenus of Punctelia by Hildur Krog in 1982; Mason Hale promoted it to generic status in 1984.
Cetrelia is a genus of leafy lichens in the large family Parmeliaceae. They are commonly known as sea-storm lichens, alluding to the wavy appearance of their lobes. The name of the genus, circumscribed in 1968 by the husband and wife lichenologists William and Chicita Culberson, alludes to the former placement of these species in the genera Cetraria and Parmelia.
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.
Menegazzia is a genus of lichenized fungi containing roughly 70 accepted species. The group is sometimes referred to as the tree flutes, honeycombed lichens, or hole-punch lichens. The most obvious morphological feature of the genus is the distinctive perforations spread across the upper side of the thallus. This makes the group easy to recognise, even for those not particularly familiar with lichen identification.
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.
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.
Notoparmelia is a genus of foliose lichens in the family Parmeliaceae. It includes 18 species that grow on bark and rocks, and are mostly distributed in the Southern Hemisphere. The genus was created in 2014 as a segregate of Parmelia.
Punctelia constantimontium is a species of foliose lichen in the family Parmeliaceae. Its range includes South America, Africa, and Mexico, where it grows on bark and twigs.
Punctelia perreticulata is a widely distributed species of foliose lichen in the family Parmeliaceae. It occurs in Mediterranean Europe and Russia, North America, South America, Australia, and New Zealand, where it grows on rocks, bark, or wood. Its main distinguishing features are its thallus surface, marked with many shallow depressions, grooves, or pits, and sorediate pseudocyphellae. The lower side of the thallus is ivory to tan towards the centre and the major secondary metabolite in the medulla is lecanoric acid. A lookalike species with which it has been historically confused is Punctelia subrudecta; this lichen can be distinguished from Punctelia perreticulata by the texture of the thallus surface, or, more reliably, by the length of its conidia.
Punctelia graminicola is a species of foliose (leafy) lichen in the family Parmeliaceae. It grows on rocks, and, less frequently, on bark in North America, South America, and East Africa. It has a blue-grey thallus measuring up to about 15 cm (6 in), covered with tiny pores called pseudocyphellae. Sometimes the lichen forms small lobes that project out from the surface. Fruiting bodies are uncommon in this species; if present, they resemble small cups with a brown internal disc measuring 3–10 mm (0.1–0.4 in) in diameter. A lookalike species, Punctelia hypoleucites, is not readily distinguishable from Punctelia graminicola by appearance or habitat alone; these species can only be reliably differentiated by examining the length of their conidia.
Punctelia borreri is a species of foliose lichen in the family Parmeliaceae. It is a common and widely distributed species, occurring in tropical, subtropical, and temperate regions of Africa, Asia, Europe, North America, Oceania, and South America. The lichen typically grows on bark of deciduous trees, and less commonly on rock. Some European countries have reported increases in the geographic range or regional frequency of the lichen in recent decades, attributed alternatively to a reduction of atmospheric sulphur dioxide levels or an increase in temperatures resulting from climate change.
Parmelia barrenoae is a species of foliose lichen in the large family Parmeliaceae. It was formally described as a new species in 2005. Before this, it was lumped together as one of several lichens in the Parmelia sulcata group—a species complex of genetically distinct lookalikes. Parmelia barrenoae is widely distributed, occurring in Europe, western North America, Africa, and Asia.
Parmelia fraudans is a species of foliose lichen in the family Parmeliaceae. It is found in Europe and North America, where it grows on rocks.
Cetraria laevigata is a species of ground-dwelling, fruticose (bushy) lichen in the family Parmeliaceae. It was formally described as a new species by Russian lichenologist Kseniya Aleksandrovna Rassadina in 1943. In North America, it is commonly known as the striped Iceland lichen.
Usnea leana is a species of fruticose lichen in the family Parmeliaceae. Found in the Galápagos Islands, it characterized by its pendulous thallus, branches covered with point-like pseudocyphellae, and the presence of galbinic acid. This lichen is currently known to be endemic to the Galápagos, with only two known localities representing its distribution.
