Lecanoraceae

Lecanoraceae is a large and diverse family of lichens, composed mainly of crustose species, with a smaller number of foliose forms. Members of this family are among the most commonly encountered lichens on rock, bark, and wood, and they occur across a wide range of habitats from forests to open, exposed sites.

Growth Form and Thallus

The thallus is most often crustose, varying from thin and smooth to thick, cracked, or areolate. Some species form well-defined rosettes, while others appear as irregular crusts. Colors range widely and include white, gray, pale green, yellow-green, brown, or orange-tinged, often influenced by secondary chemistry and exposure.

A minority of genera within the family produce foliose or squamulose thalli, but the crustose habit dominates.

Substrate and Habitat

Lecanoraceae species grow on a broad range of substrates, including siliceous and calcareous rock, tree bark, wood, and occasionally soil. They occupy habitats ranging from shaded forests to exposed rock outcrops, making them ecologically versatile and geographically widespread.

Photobiont

The photobiont is a green alga, most commonly Trebouxia.

Reproductive Structures

Sexual reproduction is frequent and often conspicuous, making this family comparatively approachable for field identification.

Apothecia: Typically lecanorine, with a thalline margin that is the same color and texture as the thallus, surrounding a usually brown to black disc. Apothecia are often round and well-defined.
Asci: Usually contain eight spores per ascus, in contrast to polysporous families such as Acarosporaceae.
Ascospores: Simple, colorless, ellipsoid to oblong, and generally larger than those of Acarosporaceae.

Asexual structures such as soredia and isidia are common in many genera and are frequently useful field characters.

Chemistry

Secondary metabolites are common and diverse in Lecanoraceae. Spot tests often yield clear diagnostic reactions (e.g., K+, C+, KC+, or UV+), and chemistry is an important tool for species-level identification. Compounds may influence thallus color, especially in yellow or greenish species.

Ecology and Role

Lecanoraceae includes many early colonizers of rock and bark, as well as long-lived, stable components of mature lichen communities. Species in this family contribute to substrate weathering, nutrient cycling, and provide microhabitats for invertebrates and other organisms.

Representative Genera

Lecanora – the type genus; highly variable crustose species with classic lecanorine apothecia
Protoparmeliopsis – often saxicolous species formerly included in Lecanora
Tephromela – thick crusts with contrasting apothecia, often on rock
Myriolecis – a segregate group with small, numerous apothecia

Similar Crustose Families

Lecanoraceae can resemble several other crustose lichen families. Acarosporaceae differs in having lecideine apothecia and many spores per ascus, rather than lecanorine margins and eight spores. Teloschistaceae often overlaps in color but is distinguished by anthraquinone pigments and strong orange or yellow tones. Rhizocarpaceae may appear similar on rock but typically has muriform, darkening spores and more strongly areolate thalli.

Family overview intended for field study and photographic reference; microscopic examination and chemical tests are often necessary for confident identification.