Stereum

Stereum is a genus of fungi in the family Stereaceae. They are characterized by their bracket-like or crust-like basidiocarps (fruiting bodies) that are typically tough and leathery or woody in texture. Many Stereum species are saprophytic, meaning they obtain nutrients from decaying organic matter, particularly dead wood. Some can also be weakly parasitic, contributing to wood decay in living trees.

The basidiocarps of Stereum fungi lack a stipe (stalk) and usually grow directly attached to the substrate. The upper surface (pileus) is often zoned or concentrically ringed with varying colors, commonly shades of brown, gray, or reddish-brown. The lower, fertile surface (hymenium) is smooth or wrinkled and lacks gills or pores, distinguishing them from many other types of bracket fungi. The spores are produced on this smooth surface.

Identification of Stereum species can be challenging and often requires microscopic examination of spores and other anatomical features. Several species are very similar in appearance, making field identification unreliable.

Some notable species within the genus include:

• Stereum hirsutum: A common species found on decaying hardwoods, known for its hairy or fuzzy upper surface.
• Stereum ostrea: Often called the "false turkey tail," it can be mistaken for Trametes versicolor (true turkey tail) but lacks pores on its underside.
• Stereum sanguinolentum: Characterized by its red staining reaction when bruised or cut, and associated with conifer wood.

While some Stereum species play an important role in nutrient cycling by decomposing dead wood, others can be detrimental to timber and structural wood due to their wood-decaying properties. They are generally not considered edible.