Exidia glandulosa: The Ultimate Mushroom Guide
About The Exidia glandulosa Mushroom
Exidia glandulosa is a common, wood-rotting species in Europe, typically growing on dead attached branches of oak. The fruit bodies are up to 3 cm (1.2 in) wide, shiny, black and blister-like, and grow singly or in clusters. Its occurrence elsewhere is uncertain because of confusion with the related species, Exidia nigricans.
In wet weather Exidia glandulosa turns black and jelly-like; however, during prolonged dry spells it shrinks to a series of cone-shaped olive-brown crusts. The individual fruitbodies sometimes coalesce to form larger blobs.
Individual fruiting bodies of Exidia glandulosa fuse together and, like something out of a bad science fiction movie, spread across sticks and small branches of hardwoods. The result is a large, quivering, black patch of gelatinous globs that eventually dry out, leaving a blackish crust on the wood. Exidia glandulosa prefers cooler temperatures, usually fruiting in spring (when it is often encountered by morel hunters) and fall.
Other names: Black Witches Butter, Black Jelly Roll, Warty Jelly Fungus.
Exidia glandulosa Identification
Saprobic; growing on recently fallen hardwood sticks and branches (especially on the wood of oaks); commonly encountered in most areas in spring and again in fall, but not infrequently appearing during summer cold spells or winter warm spells; widely distributed in North America.
Individual fruiting bodies are 1-2 cm across, but are typically fused into large patches (often over 50 cm long); gelatinous; lobed and brainlike; reddish-black to black; surface smooth or slightly rough.
Spore Print: White.
Exidia glandulosa Taxonomy & Etymology
The taxonomy of this jelly fungus is unclear, and some authorities still place it in the order Tremellales. In the USA the genus Exidia is placed under the family Auriculariaceae rather than, as in Britain, Exidiaceae.
The fungus that we know as Witches' Butter was originally described in 1789 by the French naturalist Jean Baptiste Francois (Pierre) Bulliard, who gave it the scientific name Tremella glandulosa. Then in 1822 the great Swedish mycologist Elias Magnus Fries transferred this species to the genus Exidia, but unfortunately Fries used the name Exidia glandulosa to cover not only Witch's Butter but also the jelly fungus that we know today as Exidia plana. The separation of these two species was finally clarified by Dutch mycologist Marinus Anton Donk (1908 - 1972) who in 1966 redefined the Exidia genus, clearly differentiating between Exidia plana and Exidia glandulosa.
Synonyms of Exidia glandulosa include Tremella glandulosa Bull., Tremella spiculosa Pers., Gyraria spiculosa (Pers.) Gray, Exidia truncata Fr., and Exidia spiculosa (Pers.) Sommerf.
Exidia, the generic name, means exuding or staining, and both seem appropriate because these jelly fungi do look like exudations when moist and like dark stains on wood when they dry out. The specific epithet glandulosa comes from Glandul- meaning gland, and the suffix -osa meaning abundant - a reference to the abundance of glands (papillae) on the surface of the fruitbodies of this jelly fungus.
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