[2] Most of the species of this genus grow on calcareous and acidic rocks and most of the taxa prefer temperate and arctic habitats.

[3] Members of this genus are weakly cracked to distinctly areolate, with a scattered to whole thalli.

Some possess vegetative means of propagation such as isidia (column-like structures of fungal and algal cells normally found on the top-side or outer cortex of the lichen) and soredia (structures that produce soralia, granule-like masses of intertwined fungal and algal cells occurring on top of the cortex and on the margins).

Their ascospores are typically ellipsoid to globose in shape, colorless and thin-walled.

In genus Aspicilia dramatic changes in growth forms are very common, and some taxa may display extreme transitions within the same population or even changes within the same thallus.