A genus of lichens, in which the thallus is fruticose, and attached to its substrate by a basal sheath. The ascocarps are apothecioid (see apothecium) and round or elongated. Spores are colourless and usually triseptate (see septum). Roccella species are found chiefly on rocks by the sea in warmer regions. Some have been used in the manufacture of certain dyes, including the pH indicator litmus.
Subjects: Plant Sciences and Forestry.