Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Life habit: lichenized Thallus: green, often with a yellowish tinge, usually well developed and thick, sometimes immersed, cortex sometimes disintegrating Apothecia: +red-brown, often pruinose below stalk: mostly 9-16 times as tall as the width of the stalk, 1-2 mm high, black, sometimes with a brown pruina in the upper part and a grayish pruina on the lower part; central part: consisting of densely intertwined and mainly periclinally to irregularly arranged 2-3 µm thick hyphae; outermost part: slightly paler and often with a gelationous coat capitulum: lenticular, (0.15-)0.3-0.7 mm wide; underside: often with a brown pruina exciple: dark brown, consisting of isodiametric to slightly elongated, heavily sclerotized, anticlinally arranged cells; outer surface: often covered by a smooth to strongly irregular layer of brownish, amorphous crystals; hypothecium: blackish brown with convex upper surface asci: clavate, the spores not uniseriate ascospores: semi-mature spores: with an ornamentation of spirally arranged ridges; mature spores: ellipsoid, (9-)11-13(-16) x 4-5(-6) µm, commonly incised at septum, with deep, irregular cracks Spot tests: thallus K-, C-, KC-, P-, UV+ yellow; apothecia I- Secondary metabolites: rhizocarpic acid and epanorin. Substrate and ecology: on bark, twigs or wood of Picea in old coniferous forests World distribution: Eurasia, North and South America Sonoran distribution: Arizona and southern California. Notes: Calicium viride is a very variable species, particularly with respect to ascoma size and shape, the occurrence of brown pruina and thallus thickness. It is characterized by the green, superficial thallus, brown pruina on the lower side of its capitulum, forming a red, crystalline precipitate with K, and the very irregular ornamentation of its mature spores. Specimens with immersed thalli are quite similar to