Lepraria is a genus of leprose (powdery) crustose lichens that grows on its substrate like patches of granular, caked up, mealy dust grains.

[10] Scientists use multiple characteristics to identify and classify Lepraria species, including their physical appearance (morphology), their chemical composition, and their genetic sequences.

While some researchers have proposed splitting the genus into many narrowly defined species based on small genetic or chemical differences, others advocate for a more conservative approach that considers multiple lines of evidence.

[11] Species of Lepraria are characterised by their powdery, crustose thalli, which are composed almost entirely of soredia—small, granular clusters of fungal and algal cells that allow for asexual reproduction.

The thallus may appear loosely attached or more firmly integrated with the substrate, forming irregular, diffuse patches or well-defined, lobed margins.

[12] The genus Lepraria is chemically diverse, with species producing a wide range of secondary metabolites, including depsides, depsidones, aliphatic acids, and terpenoids.

[12] While Lepraria is often associated with moist microhabitats, certain species tolerate or even prefer more exposed conditions, such as sunlit rock faces or dry forest floors.

The highest species diversity is found in temperate zones, but representatives of Lepraria are also common in tropical and boreal forests, alpine regions, and oceanic islands.