Black Witch's Butter

Appearance

"Exidia glandulosa" forms dark sepia to blackish, rubbery-gelatinous fruit bodies that are top-shaped and around 3 cm across. They are firm when fresh, but become lax and distorted with age or in wet weather. The fruit bodies occur singly or in small clusters. The upper, spore-bearing surface is shiny and dotted with small pimples or pegs. The undersurface is smooth and matte at first, but develops a dense covering of small, gelatinous spines. The fruit bodies are attached to the wood at the base. The spore print is white. When the fruit bodies are dried they can shrink to form a flattened black crust.

Naming

"Exidia glandulosa" is frequently confused with "Exidia nigricans". The two are similar, but "E. nigricans" produces button-shaped fruit bodies in clusters that quickly become deformed and coalesce, forming an effused, lobed mass that can be 10 cm or more across. The two species are indistinguishable microscopically, but DNA research indicates they are distinct. The closely related "E. recisa" has more erect fruit bodies without warts on the surface, lighter colors, and a small base.

The ascomycete "Bulgaria inquinans" forms similar, rubbery-gelatinous, blackish fruit bodies on oak. Their upper surfaces are entirely smooth, however, and they produce copious black spore prints, often leaving a black stain if wiped with the hand.

Distribution

"Exidia glandulosa" is a wood-rotting species, typically found on dead attached branches of broadleaf trees, especially oak, occasionally hazel or beech. It is a pioneer species capable of colonizing living or recently dead wood. A study of the wood decay process in attached oak branches showed that "E. glandulosa" is a member of a community of eight basidiomycetous fungi consistently associated with the decay of dying branches on living trees. Specifically, its role is to disintegrate the tissue of the vascular cambium, which loosens the attached bark. It persists for some while on fallen branches and logs. Fruit bodies are normally produced in the autumn and winter. Its global distribution is uncertain because of confusion with "E. nigricans", but it is present in Europe at least.

Habitat

"Exidia glandulosa" is a wood-rotting species, typically found on dead attached branches of broadleaf trees, especially oak, occasionally hazel or beech. It is a pioneer species capable of colonizing living or recently dead wood. A study of the wood decay process in attached oak branches showed that "E. glandulosa" is a member of a community of eight basidiomycetous fungi consistently associated with the decay of dying branches on living trees. Specifically, its role is to disintegrate the tissue of the vascular cambium, which loosens the attached bark. It persists for some while on fallen branches and logs. Fruit bodies are normally produced in the autumn and winter. Its global distribution is uncertain because of confusion with "E. nigricans", but it is present in Europe at least.