Calicium viride
Calicium viride, commonly known as the green stubble lichen, is a species of pin lichen in the family Caliciaceae, and the type species of the genus "Calicium". It is a common and widely distributed species in temperate areas of the Northern Hemisphere and southern South America. Taxonomy. It was described as a new species by Christiaan Hendrik Persoon in 1794. "Calcium viride" is the type species of the genus "Calicium". The common name for the lichen in North America is "green stubble lichen". The "Calicium viride" group is the name of a clade of closely related species that  all have ascomata supported on relatively large and sturdy stalks, and spores with a distinctive spiral ornamentation. This group also includes "C. corynellum", "C. salicinum", and "C. quercinum", as well as "Cyphelium lecideinum", which lacks a stalk but also has spiral-striated spores. Description. "Calicium viride" has a greenish-yellow thallus with a granular texture that grows as a crust on the surface of its substrate. The small black stalks, 1.5–2.5 mm long and roughly 0.1–0.15 mm thick, support the spore-bearing structures: at the tip of each stalk is a "capitulum"–a spherical apothecium. The capitula are black with a  brownish underside. "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. It contains the secondary chemicals rhizocarpic acid and epanorin. Habitat and distribution. The lichen is common on the bark and wood of conifer trees in montane forests, but sometimes grows on deciduous trees.