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Birch Woodwart

Inedible Inedible
Autumn Autumn
Spring Spring
Summer Summer
Winter Winter

Looks like a spoonful of caviar on dead branches or trunks of a birch.

Mushroom Type
Common Names Birch Woodwart (EN), Dafaden Bedw (CY), Drewniak Wielokształtny (PL), Változékony Ripacsgomba (HU)
Scientific Name Jackrogersella multiformis
Synonyms Annulohypoxylon multiforme, Hypoxylon multiforme, Sphaeria multiformis
Season Start All Year
Season End All Year
Average Mushroom height (CM)
Average Cap width (CM)
Please note that each and every mushroom you come across may vary in appearance to these photos.

Fruiting Body

It is one of the stroma-forming Ascomycetes.
The stroma is a 0.5–1.0 cm thick, irregularly cushion-like, lumpy layer, growing horizontally on the bark of birch trees. Originally reddish brown then black. Surface uneven, bumpy (pimple-dotted). Individual stromata could emerge to form a big patch.

stroma (singular) or stromata (plural) is a cushion-like mass of fungal hyphae that produces perithecia
hypha (singular) or hyphae (plural) a filamentous thread of fungal mycelium
perithecium (singular) or perithecia (plural) is a cylindrical to flask-shaped hollowed fruiting body which contains the asci
ascus (singular) or asci (plural) is the spore-producing cell of an ascomycete fruit body


Tough, brittle, black.


Saprotrophic on wood, mostly on Birch, rarely on other hardwoods, such as Alder, Hazel or Poplar. Can be found all year long in parklands, woodlands, and everywhere where dead birch trees are.

Possible Confusion

Beechwood Woodwart (Jackrogersella cohaerens), pictured, looks almost identical, but it grows exclusively on Beech (Fagus).


It is very common and widespread in the UK.


Ellipsoid to bean-shaped, slightly flattened down on one side. Smooth, dark brown with a single oil-like droplet (guttule) within.

Other Facts

Birch Woodwart is the type species of a relatively new genus, Jackrogersella which only contains 6 species worldwide. This new genus was proposed only in 2017, and based on chemical and DNA evidence, it had been accepted. Birch Woodwart was formerly in genus Annulohypoxylon, that had been created from the species of the former Hypoxylon sect. Annulata in 2005.


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