A podetium (plural: podetia) is the upright secondary thallus in Cladonia lichens. It is a hollow stalk extending from the primary thallus. [1] Podetia can be pointed stalks, club like, cupped, or branched in shape and may or may not contain the ascocarp, the fruiting body, of the lichen. [2] It is not considered part of the primary thallus as it is a fruiting structure for reproduction.
A lichen can be described as "podetiate" when it forms a podetium.
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.
The Cladoniaceae are a family of lichenized fungi in the order Lecanorales. It is one of the largest families of lichen-forming fungi, with about 560 species distributed amongst 17 genera. The reindeer moss and cup lichens (Cladonia) belong to this family. The latter genus, which comprises about 500 species, forms a major part of the diet of large mammals in taiga and tundra ecosystems. Many Cladoniaceae lichens grow on soil, but other can use decaying wood, tree trunks, and, in a few instances, rocks as their substrate. They grow in places with high humidity, and cannot tolerate aridity.
Soredia are common reproductive structures of lichens. Lichens reproduce asexually by employing simple fragmentation and production of soredia and isidia. Soredia are powdery propagules composed of fungal hyphae wrapped around cyanobacteria or green algae. These can be either scattered diffusely across the surface of the lichen's thallus, or produced in localized structures called soralia. Fungal hyphae make up the basic body structure of lichen. The soredia are released through openings in the upper cortex of the lichen structure. After their release, the soredia disperse to establish the lichen in a new location.
Lecanora is a genus of lichen commonly called rim lichens. Lichens in the genus Squamarina are also called rim lichens. Members of the genus have roughly circular fruiting discs (apothecia) with rims that have photosynthetic tissue similar to that of the nonfruiting part of the lichen body (thallus). Other lichens with apothecia having margins made of thallus-like tissue are called lecanorine.
Cladonia furcata or the many-forked cup lichen is a species cup lichen in the family Cladoniaceae. It has an intermediate to tolerant air pollution sensitivity. Extracts of this species have been shown to kill leukemia cells in vitro, and may have possible value in the treatment of cancer.
Pilophorus acicularis, commonly known as the nail lichen or the devil's matchstick lichen, is a species of matchstick lichen in the family Cladoniaceae.
Pertusaria is a large genus of warty crustose lichens in the Pertusariaceae family. The fruiting bodies are usually modified apothecia that immersed in warts on the main body (thallus) with small holes for the spores to emerge, similar to ostioles, or are fully above and lecanorine (spore bearing discs surrounded by a ring of tissue similar to the tissue of the thallus. Members of the genus are commonly called wart lichens.
Foliose lichen is one of the morphological classes of lichens, which are complex organisms that arise from the symbiotic relationship between fungi and a photosynthetic partner, typically algae. This partnership allows lichen to live in diverse climates that can range from cold, dry mountains to wet, warm valleys. Lichens develop quite slowly with recorded growth rates of 0.01–27mm/year depending on the species. Their lifespan averages between 30 and 60 years.
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. 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.
Baeomyces rufus, commonly known as the brown beret lichen, is a fruticose lichen belonging to the cap lichen family, Baeomycetaceae. The species was first described by J.F Rebentisch in 1804. Like other lichens, it is a symbiosis between a fungus and an alga.
Cladonia amaurocraea, commonly known as the quill lichen or the quill cup lichen, is a species of fruticose, cup lichen in the Cladoniaceae family.
Cladonia sobolescens, commonly known as the peg lichen, is a species of fruticose lichen. It is found in temperate eastern North America and East Asia.
Cladonia digitata, commonly known as the finger cup lichen, is a cup lichen species in the family Cladoniaceae.
Flavopunctelia praesignis is a species of foliose lichen in the family Parmeliaceae. It was first described as Parmelia praesignis by Finnish botanist William Nylander in 1872. In 1982, Hildur Krog transferred it to the subgenus Flavopunctelia of her newly circumscribed genus Punctelia, created to contain Parmelia species with punctate (point-like) pseudocyphellae. Mason Hale raised this subgenus to generic status a couple of years later. The lichen is colloquially known as the fruiting speckled greenshield. It is found in the southern United States, in various states of Mexico, and in South America. It has also been reported from Kenya, but that may be due to misidentification.
Hypogymnia krogiae, commonly known as the freckled tube lichen, is a species of foliose lichen in the family Parmeliaceae. Found in North America, it was described as a new species in 1973 by Karl Ohlsson. The type specimen was collected near Cheat Bridge, West Virginia by Mason Hale in 1956.
Pulchrocladia retipora, most commonly known as the coral lichen, is a species of fruticose lichen in the family Cladoniaceae. It occurs in Australasia and New Caledonia where it grows in coastal and alpine heathlands. The lichen features coral-like branches and subbranches with numerous netlike perforations. It is known by multiple names, with some sources referring to it by its synonym Cladia retipora, or the common name lace lichen.
The following outline provides an overview of and topical guide to lichens.
Cladonia longisquama is a species of fruticose lichen in the family Cladoniaceae. It occurs in the Seychelles, where it grows on moss-covered rocks.