Daldinia concentrica

Daldinia concentrica
Scientific classification
Kingdom:	Fungi
Division:	Ascomycota
Subdivision:	Pezizomycotina
Class:	Sordariomycetes
Subclass:	Xylariomycetidae
Order:	Xylariales
Family:	Xylariaceae
Genus:	Daldinia
Species:	D. concentrica
Binomial name
Daldinia concentrica (Bolton) Cesati & de Notaris

Daldinia concentrica
Mycological characteristics
	glebal hymenium
	no distinct cap
	hymenium attachment is not applicable
	lacks a stipe
	spore print is black
	ecology is saprotrophic
	edibility: inedible

The inedible fungus Daldinia concentrica is known by several common names, including King Alfred's Cake, cramp balls, and coal fungus. It can be found in North America and Europe, where it lives on dead and decaying wood, especially on felled ash trees. It is a common, widespread saprotroph.

The fungus is ball-shaped, with a hard, friable, shiny black fruiting body 2 to 7 centimeters wide. It resembles a chunk of coal, which gives it several of its common names, including coal fungus and carbon balls. According to legend, King Alfred once hid out in a countryside homestead during war, and was put in charge of removing baking from the oven when it was done. He fell asleep and the cakes burned. Daldinia concentrica is said to resemble a cake left to this fate.

The flesh of the fungus is purple, brown, or silvery-black inside, and is arranged in concentric layers. Each layer represents a season of reproduction. The asci are cylindrical and arranged inside the flask-shaped perithecium. When each ascus becomes engorged with fluid it extends outside the perithecium and releases spores.

D. concentrica contains several unique compounds, including a purple pigment from a perylene quinone and a metabolite called concentricol, which is oxidized squalene. Many types of insects and other small animals make their home inside this species of fungus.

The fungus is a useful form of tinder for fire-lighting. The brown variety is usually too heavy and dense to be much good; the black variety is lighter and better. It does need to be completely dry, whereupon it will easily take a spark from a firesteel. It burns slowly, much like a charcoal briquette, with a particularly pungent smoke. Once lit it is quite difficult to extinguish, but fragments can be broken off and transferred to a tinder ball to create an open flame.

Caterpillars of the concealer moth Harpella forficella have been found to eat this fungus.

External links

• arkive.org page
• Fungus atlas page
• King Alfred's Cake

References

• Glick, Phyllis. (1979) The Mushroom Trail Guide. 1st ed. New York, NY: Holt, Rinehart And Winston.
• Singh, Jagjit. (1994) Building Mycology: Management of Decay and Health in Buildings. UK: Spon Press.