Most species are found at high latitudes, occurring on sand or heath, and are characterised by their "strap-like" form with spiny lobe edges.

Several Cetraria species have cultural and economic importance, particularly C. islandica (Iceland moss), which has been widely used in European traditional medicine for treating digestive and respiratory ailments.

This species was also historically important as a famine food in Northern Europe and continues to find applications in modern cosmetics and pharmaceutical products.

Cetraria species are also ecologically important, serving as indicators of air quality and climate change due to their sensitivity to environmental conditions and ability to accumulate various elements, including potentially toxic heavy metals and radioactive isotopes.

He noted that its apothecia (fruiting bodies) were intermediate between the scutellate and peltate types found in related genera, which along with other morphological features meant that species in this genus could not be properly placed in either Parmelia or Peltidea.

Although new genera were subsequently established—including Nephromopsis by Johannes Müller Argoviensis (1891)[5] and Tuckermannopsis by Vilmos Kőfaragó-Gyelnik (1933)[3]—most lichenologists continued to favour a broader concept of Cetraria.

This process started with the description of Asahinea and Platismatia,[8][9] and continued over subsequent decades with the recognition of additional genera including Masonhalea, Ahtiana, Allocetraria, Vulpicida, Cetrariella, Arctocetraria, and Flavocetraria, among others.

[14] By 2011, researchers found that approximately half of the accepted genera within this core group were not actually monophyletic, suggesting the existing classification required further refinement.

Their analyses revealed that many cetrarioid genera had been more narrowly circumscribed than comparable groups within Parmeliaceae, leading to debates about whether some previously split taxa should be reunited.

They proposed to synonymise Allocetraria (and several other genera) with Cetraria, because the former group of species originated relatively recently and fell under the timeframe threshold for genus level.

[19] However, some researchers maintain that strict application of temporal phylogenetics methodology for genus delimitation in the Parmeliaceae could have important implications for conservation legislation.

[19] A pragmatic approach to this taxonomic complexity appears in Bruce McCune and Linda Geiser's 2023 field guide to Pacific Northwest macrolichens, where they adopt a broad concept of Cetraria (including Nephromopsis) based on available molecular and morphological data, while acknowledging that generic placement within cetrarioid lichens remains unsettled.

[20][21] The genus name Cetraria is derived from the Latin cetra, meaning 'a type of leather shield' combined with the suffix -aria, indicating connection or possession.

[19] The asci (spore-producing cells) are eight-spored, narrowly club-shaped (clavate), and feature a moderately large tholus (internal structure) with an apical ring and a conical ocular chamber that may have a narrow to broad beak.

In contrast, several species have highly restricted ranges – C. annae and C. rassadinae are endemic to Russia's Baikal region, while C. australiensis is found only in southeastern Australia.

The genus also shows promise in monitoring climate change impacts, as different species have varying sensitivities to temperature, ultraviolet light exposure, and humidity levels.

Additionally, Cetraria species play a role in ecosystem health through their ability to absorb and accumulate various elements, including potentially toxic metals and radioactive isotopes.

For example, the bipolar distribution pattern of C. aculeata appears to have originated in the Northern Hemisphere, with subsequent dispersal to Antarctica and South America during the Pleistocene.

[7] The current lower number reflects taxonomic revisions since the 1960s that have moved many species to other genera, though the exact circumscription remains debated among lichenologists.

[25] Unlike other lichen genera such as Parmotrema or Usnea, which show considerable interspecific variation in their chemical profiles, Cetraria has relatively consistent patterns in its secondary metabolite composition.

A notable example of chemical variation's taxonomic significance is seen in C. steppae, where the presence of norstictic acid helped distinguish it from the closely related C. aculeata.

Environmental factors can influence the production of these compounds, as demonstrated by the variation in norstictic acid concentrations in C. aculeata/steppae populations growing in Mediterranean and central Asian regions.

Recent studies have also highlighted the importance of melanins (particularly allomelanins) in these lichens, which provide essential UV protection and may contribute to survival in harsh conditions.

It served as an important food source, particularly during times of scarcity in Northern Europe, where it was often mixed with rice or flour to make bread.

[25] In Iceland, where historically it was a staple food,[44] the lichen was incorporated into various traditional dishes, including soups, porridges, and sausages, and was added to "skyr" (a type of curd).

Current research continues to explore new potential therapeutic applications, including cytotoxic and genotoxic/antigenotoxic activities, expanding our understanding of these historically important lichens.

[45] Cetraria species serve as effective biological monitors due to their sensitivity to environmental changes and ability to absorb various substances from their surroundings.

Their value in environmental monitoring stems from their lack of a protective cuticle (unlike higher plants) and their air-dependent nutrition, which makes them particularly responsive to atmospheric changes and pollutants.

[25] Biomonitoring with Cetraria species can be conducted through several approaches: analysing their accumulation of trace elements, studying their biodiversity in specific areas, and examining cell membrane integrity.

Research in Mediterranean ecosystems has revealed that Cetraria specimens from high-elevation areas often show increased levels of potentially toxic elements, possibly due to long-distance transport and cold condensation processes.