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Daldinia concentrica

King Alfred's Cakes / Cramp Balls

(Bolton) Ces. & De Not., 1863

Detailed Texts Multi-lang

Daldinia concentrica is an unmistakable ascomycete fungus that resembles pieces of charcoal attached to wood. The fruiting body (stroma) is globose or hemispherical, 2 to 10 cm in diameter, with a smooth surface that matures from reddish-brown to a dull coal-black. Its most fascinating feature is revealed when cut: the interior shows silver and black concentric rings reminiscent of a tree's growth rings. The surface is dotted with tiny pores (perithecia) where spores are produced. It is a hard, dry, and persistent fungus that lacks a stalk and grows directly on decaying broad-leaved tree logs. Its 'burnt cake' appearance is a clear sign of its identity in the forest ecosystem.

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Julia Trouin

Taxonomy

PhylumAscomycota

ClassSordariomycetes

OrderXylariales

FamilyHypoxylaceae

GenusDaldinia

Taxonomic Authority(Bolton) Ces. & De Not., 1863

Ecology & Status

Origin

Native

Population Trend

Stable

Edibility

Cap Shape

Hymenium Type

Fruiting Season

Year Round

Recent Sightings

Yes

Habitat Summary Multi-lang

It inhabits deciduous and mixed forests, growing almost exclusively on logs and fallen branches of broad-leaved trees, with a marked preference for the Fraxinus (ash) genus, though it colonizes other hardwoods. It prefers environments with seasonal humidity, but its structure allows it to persist in dry conditions. In Costa Rica, it is found in mid and low-elevation forested areas, taking advantage of decaying wood from native species year-round.

Substrate Multi-lang

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Behaviour Multi-lang

It is a saprophytic hardwood decomposer causing white rot. It plays a crucial role in carbon recycling by breaking down complex wood polymers. Unlike other fungi, it has a prolonged and nocturnal spore release cycle. It serves as habitat for specialist insects, especially moths of the Tineidae family that feed on its structure.

Physical Measures

Length (cm)

2.0 - 10.0 cm

Hymenium Structures

No hymenium surface images available.

Evolutionary Adaptations Multi-lang

Zoned Interior for Water Storage: The internal concentric rings act as moisture reservoirs. This adaptation allows the fungus to continue releasing spores during drought periods, even when the external environment is arid, giving it an advantage over fleshier fungi.

Protective Carbonized Stroma: Its hard, black surface is highly resistant to insect attack and UV radiation, protecting the internal perithecia while the wood slowly decomposes.

Main Threats Multi-lang

Intensive forestry practices: Removal of dead wood and overly clean forest management reduce available substrates for this fungus.

Interesting Facts Multi-lang

King Alfred's Cakes: The name comes from an English legend where King Alfred the Great, hiding in a cottage, let some cakes burn that he was supposed to watch. Seeing these black fungi, people joked they were the king's burnt cakes.

Natural Tinder: Once dry, these fungi are excellent for starting fires. They can maintain a smoldering coal internally for a long time without a flame, allowing ancient fire-carriers to transport fire between locations.