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Cetraria: A Genus of Fruticose Lichens

The genus Cetraria encompasses a variety of fruticose (shrub-like) lichens. These fascinating organisms are a symbiotic partnership between a fungus and green algae (photobionts).

Nomenclature and Taxonomy

• Scientific Name: Cetraria Ach.
• Family: Parmeliaceae
• Group: Lichen
• Symbol: CETRA2

Distribution and Habitat

• Most Cetraria species are found at high latitudes.
• They commonly occur on sand or heath environments.
• Some species, like Cetraria aculeata, have a bipolar distribution.
• Cetraria islandica is circumpolar, abundant in the arctic and mountainous regions of northern countries.

Morphological Characteristics

• Cetraria islandica has an erect or upright, leaflike (foliose) habit, giving it a moss-like appearance.
• Cetraria islandica is a LICHEN growing to 0.1 m (0ft 4in) by 0.5 m (1ft 8in) at a slow rate.
• The thallus (body) of Cetraria islandica varies in color from deep brown to grayish white.
• Some species, like Cetraria islandica, exhibit marginal projections and pseudocyphellae (small pores) on their thallus.
• Cetraria islandica fruticose (branched, bushy) lichen with an upright thallus usually attached in one place.
• Cetraria aculeata is a dark brown, branched lichen growing on coastal sand dunes. Branches shiny and flattened with white pseudocyphellae in pits.

Cetraria islandica (Iceland Moss)

• Common Names: Iceland moss, Iceland lichen
• Synonyms: Lichen islandicus, Cetraria (Lichen islandicus)
• Cetraria islandica subspecies crispiformis is one of the two subspecies of "true Iceland lichen".
• Cetraria islandica var. polaris is a recognized form.

Traditional Uses and Bioactivity

• Iceland moss (Cetraria islandica) has a long history of use as a cough remedy.
• It has also been used in European folk medicine as a cancer treatment.
• Iceland moss possesses both demulcent and bitter properties.
• Extracts from Cetraria aculeata exhibit antimicrobial activity due to the presence of protolichesterinic acid.
• Studies have evaluated the antioxidant activity of aqueous extracts of Cetraria islandica.
• Chemical investigations of Cetraria islandica have led to the isolation of compounds like protolichesterinic acid and lichesterinic acid.

Ecological Role

• Terrestrial ecosystems of the Antarctic are largely dominated by lichens, including Cetraria aculeata.

Genetic Information

• Studies are exploring the genetic diversity of different populations of lichen fungi, including Cetraria aculeata, and their algal partners.

Interactions with Other Organisms

• Cetraria lichens form symbiotic relationships with green algae as photobionts.
• Cetraria species have symbiotic interactions.

Further Information

• Biodiversity Heritage Library: http://www.biodiversitylibrary.org/part/100498
• Lichens of North America, Yale University Press.