A genus of lichens in which the thallus is crustose and may be more or less immersed in the substratum. Spores are colourless and aseptate. Apothecia are characteristically lecideine. The genus originally included numerous species but has now been divided into many different genera. Individual species can usually be recognized only by microscopic examination. They are found on a wide range of substrates.
Subjects: Plant Sciences and Forestry.