Established by German lichenologist Gustav Wilhelm Körber in 1859, this genus of crustose lichens is characterised by its black, sessile apothecia (fruiting bodies), muriform ascospores, and growth on mosses, plant debris, and rocks in montane habitats.

[4][5] In the 2024 Revisions of British and Irish Lichens series, the genus Schadonia is described as having an "uncertain position within the Lecanorales", and the possibility of resurrecting the family Schadoniaceae,[6] originally proposed by Josef Hafellner in 1984,[7] is mentioned.

[6] The fruiting bodies of Schadonia, the apothecia, are black, disc-shaped structures that sit directly on the surface of the lichen without a stalk (sessile) and are slightly constricted at the base.

Surrounding the apothecia is a prominent true exciple, a structure made up of cells arranged in a radial pattern, giving it an even or slightly wavy appearance.

When treated with a chemical solution of potassium iodide (K/I+), the spore sacs stain blue, a feature characteristic of the Bacidia-type asci.