''Hypogymnia physodes'', commonly known as the monk's-hood lichen, is a species of

foliose lichen A foliose lichen is a lichen with flat, leaf-like , 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 o ...

in the family

Parmeliaceae 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'' ( 82 ...

. It is a common and widespread species in

boreal Boreal, northern, of the north. Derived from the name of the god of the north wind from Ancient Greek civilisation, Boreas (god), Boreas. It may also refer to: Climatology and geography *Boreal (age), the first climatic phase of the Blytt-Sernand ...

and

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

forests of the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...

. It has a grey to yellowish-green

thallus Thallus (: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. A thallus usually names the entir ...

that is loosely attached to its

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...

and forms large irregular patches. Hollow lobes are 2–3mm wide. The outer edge turns up and is frequently covered with white powdery

soredia Soredia are common reproduction, reproductive structures of lichens. Lichens asexual reproduction, reproduce asexually by employing simple fragmentation and production of soredia and isidia. Soredia are powdery propagules composed of fungus, fung ...

underneath. Its lower surface is black, wrinkled and has some browning toward the lobe margins. The

pycnidia A pycnidium (plural pycnidia) is an asexual fruiting body produced by mitosporic fungi, for instance in the order Sphaeropsidales ( Deuteromycota, Coelomycetes) or order Pleosporales (Ascomycota, Dothideomycetes). It is often spherical or inve ...

are black and abundant, and their presence creates a pepper-like effect across the upper surface. Because of its abundance and its moderate sensitivity to

sulphur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...

and

heavy metals upright=1.2, Crystals of lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead Heavy metals is a controversial and ambiguous term for metallic elements with relatively h ...

, ''Hypogymnia physodes'' is often used in

bioindicator A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other sma ...

and

biomonitoring In analytical chemistry, biomonitoring is the measurement of the body burden of toxic chemical compounds, elements, or their metabolites, in biological substances. Often, these measurements are done in blood and urine. Biomonitoring is performe ...

studies that enable the assessment of

air pollution Air pollution is the presence of substances in the Atmosphere of Earth, air that are harmful to humans, other living beings or the environment. Pollutants can be Gas, gases like Ground-level ozone, ozone or nitrogen oxides or small particles li ...

and other environmental conditions.

References

{{Taxonbar, from=Q881824

physodes Phlorotannins are a type of tannins found in brown algae such as kelps and rockweeds or sargassacean species, and in a lower amount also in some red algae. Contrary to hydrolysable or condensed tannins, these compounds are oligomers of phlorogl ...

Lichen species Lichens described in 1753 Lichens of North America Lichens of Asia Lichens of Europe Taxa named by Carl Linnaeus