It is a common and widely distributed species in temperate areas of the Northern Hemisphere and southern South America.

Diagnostic characteristics of Calicium viride are its brown excipulum (the ring of tissue around its apothecia), and its green, granular crust.

The taxonomic relationship between the two species has been clarified through molecular phylogenetics analyses using nuclear ITS DNA sequences, which confirmed that these two taxa are distinct.

Morphological differences are significant, with C. corynellum characterised by short-stalked, greyish-white pruinose ascomata and narrower spores, in contrast to the long stalks and brown pruina of C. viride.

[3] Calicium corynellum is a rarer species that is somewhat similar in appearance to C. viride, but it grows on rock instead of wood or bark, and it has shorter stalks, typically 0.5–0.6 mm long.

Calicium viride typically presents with longer stalks and a brown pruina covering its ascomata, which are usually greenish at maturity.