Lecanoromycetes

Lecanoromycetes is a class of fungi within the phylum Ascomycota, subphylum Pezizomycotina. It is the largest class in Ascomycota by species diversity and includes the majority of lichen-forming fungi as well as a number of non-lichenized species.

Most members are lichenized, forming symbiotic associations with photosynthetic partners such as green algae or cyanobacteria. The resulting lichens display a wide range of growth forms, including crustose, foliose, and fruticose morphologies, and inhabit diverse environments from bare rock and tree bark to soil and extreme habitats. Lecanoromycete lichens contribute to rock weathering, soil formation, and nutrient cycling and are frequently used as indicators of air quality and ecological continuity. The group also includes non-lichenized fungi that may be saprobic or parasitic, illustrating ecological diversity within the class.

Taxonomy within Lecanoromycetes comprises several orders, notably Lecanorales, Peltigerales, Teloschistales, and Lecideales, among others. Classification has been refined in recent decades through molecular phylogenetics, leading to revised circumscriptions of families and genera and a clearer understanding of relationships among lichen-forming lineages.

Reproduction in the class involves the production of asci containing ascospores within fruiting bodies such as apothecia or perithecia. Many lichens also reproduce asexually through vegetative propagules like soredia or isidia. Lecanoromycetes synthesize a wide array of secondary metabolites, contributing to thallus chemistry and providing chemotaxonomic characters used to distinguish taxa.

Overall, Lecanoromycetes represent a major component of terrestrial ecosystems and a key focus for studies of symbiosis, biodiversity, and environmental change.