Fuscideaceae is a family of fungi that form symbiotic relationships with algae to create lichens. These lichens typically have a crust-like appearance and are found worldwide, though they are most common in temperate regions. The family includes four genera and about 45 species, which primarily grow on tree bark, rocks, or occasionally on wood or leaves. Fuscideaceae lichens are characterised by their reproductive structures, cup-like formations called apothecia, which can vary in colour from red to dark brown or black. The family has undergone several changes in its classification over the years, with recent genetic studies placing it within the order Umbilicariales. Fuscideaceae lichens produce various chemical compounds (lichen products), some of which are unique to this family, and these chemicals are often used to help identify different species.

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