This common and widespread species has a cosmopolitan distribution, often found in dry, sunny habitats on basic soils, limestone, and nutrient-rich silicate substrates.

The lichen forms rosettes up to 20 cm (8 in) in diameter, with a grey to brown thallus densely covered with a soft, velvety tomentum.

The species is notable for its ability to bioaccumulate heavy metals and its adaptive responses to ultraviolet-B radiation, making it a subject for ecological and physiological studies.

[3] Later in its taxonomic history, other authors proposed that it be transferred to the now defunct genus Peltidea, or that it best be considered as a variety or subspecies of Peltigera canina.

P. rufescens also has free amino acid concentrations higher than other lichens in similar polluted habitats, comparable to vascular plants, suggesting that this may play a role in heavy metal tolerance.

[13] In 1971, Marie-Agnès Letrouit-Galinou and R. Lallemant published a study on the thallus, apothecia, and asci of Peltigera rufescens, using histological techniques and microscopic examination.

The formation of apothecia is initiated by a limited number of marginal dorsal pleuridia, leading to a primary thallus resembling those in the families Lecanoraceae and Graphidaceae, with a distinct development process marked by a lengthy angiocarpic stage (a phase in the development where the apothecium is initially formed as a closed structure, enclosing the asci and ascospores).

[16] Not only does the moss provides a buffer against extremes in temperature variation, the moss-associated thalli have higher photosynthetic rates, and increased protection against desiccation.

Mosses that have been recorded associating with Peltigera rufescens include Racomitrium heterostichum, Campylopus introflexus, Hypnum cupressiforme, and Polytrichum juniperinum.

In the case of Scutula didymospora, the relationship appears to be commensalistic, as the fungus, which develops on the underside of the thallus, does not cause any damage, discolouration or galls.

[20] In one experiment, to test the effect of thallus hydration on metabolic activity, the photosystem II fluorescence of Peltigera rufescens was monitored for a full year.

Like other Peltigera lichens, P. rufescens appears able to acquire microorganisms from the soils in which it grows, suggesting that local environments serve as reservoirs for components of its microbiome.

[23] This diverse microbial community likely contributes to the lichen's overall ecological function and resilience, though the specific roles of many associated microorganisms remain under investigation.

The presence of these microbial communities demonstrates that P. rufescens, like other lichens, functions not just as a symbiotic partnership between fungus and photobiont, but as a complex microscopic ecosystem.