Stereum is the type genus of the Stereaceae family of fungi, in the Russulales order. Until recently, the genus was classified in the Corticiaceae family, of the Corticiales order. However, it was given its own family as a result of the split-up of the Corticiales. Common names for species of this genus include leaf fungus, wax fungus, and shelf fungus. Fungi having a shape similar to a Stereum are said to have a stereoid shape. Stereum contains 27 species that have a widespread distribution.
Stereum species are found to live on all kinds of deadwood or hardwood or dead leaves (they are therefore said to be saprobic). Sometimes they are also found on living leaves.
Stereum species are wood decay fungi. Their simple, shelving fruiting bodies have a smooth hymenium, lacking gills or tubes. Like most members or the family Stereaceae, Stereum fruiting bodies lack clamp connections and produce amyloid basidiospores.
The species can be divided into two groups: the bleeders (those that exude a red liquid from cut surfaces, similarly to Lactarius species) and the non-bleeders (those that do not). In 1959, Zdenek Pouzar created a distinct genus, Haematostereum, for the bleeding species of Stereum, including H. gausapatum, H. rugosum, and H. sanguinolentum. Modern authors do not consider Haematostereum to be a distinct genus, so it is currently treated as a synonym of Stereum.
