foraging fungi

The fiery nature of King Alfred’s Cakes

The story goes that King Alfred, exhausted from battle, filthy, and lost in the woods, was given shelter by a herdsman’s family. In his unkempt state, they didn’t recognize him as the king, and thought he was a tired soldier.

The wife was in the middle of baking bread on the hearth, and asked the King to watch the fire while she went to fetch more wood. While she was out, he fell asleep and she returned to find the loaves burnt. Scolding him for his carelessness, and the wife expressed surprise that anyone would not understand the importance of tending to the bread. What sort of person doesn’t understand such a basic household task?

In one version of the story, King Alfred scatters the burnt loaves in the woods to hide his mistake.

Enter Daldinia concentrica. Also known as “King Alfred’s Cakes”.

Daldinia growing on decaying wood. Tiny burnt loaves.

But the story of the burnt loaves is not this fungus’ only connection to fire…

King Alfred’s Cakes are also sometimes referred to as “coal balls” or “carbon cakes” or “carbon balls”.

But much like the legend, the exact details of why depend on who you ask.

Some say that the “coal” name comes from Daldinia‘s sooty spores. Spores of Daldinia are ejected through little tubes (perithecium) at the outermost layer of the fungus. You can see these tubes in the cross section photo below. The ejected spores look like a fine black powder, and the “soot” this fungus leaves behind certainly do make you think of carbon or coal.

Half a Daldinia. The perithecium (the tubes from which spores are ejected) are visible on the outer layer. Consensus is that each concentric ring represents a season’s growth.

However, there is another explanation. One that ignited my interest, as it were.

Because Daldinia has another unusual and interesting property: an ability to catch and hold fire. This fungus ignites quickly, but smoulders slowly.

This mushroom can carry fire.

Now, if you hand me information like that, there is one more thing you have to hand me. Matches.

I took my tiny Daldinia sample over to the fire pit, and, well, here’s what happened…

Now that’s what I call confirming an ID! I conducted this experiment around 6am one morning before getting started on work, and it made my whole dang day. I’m still high on it.

Daldinia are quite common, and this fiery property may have historically made this fungus a useful “tool” to forage: as a vessel for moving fire from one place to another, or as tinder. Using fungus as tinder would not be unique to Daldinia. This was also famously concluded as the reason that Fomes fomentarius, “hoof” fungus, was one of two fungi found in the travel equipment of Ötzi the Iceman’s 5000 year old mummified remains.


It’s all still there, even when we fail to notice. The raw materials for heart-rending heart-mending fascination. Both the tinder and the spark. The embers of science and magic in the tiny un-flashy fungi, and the sense of wonder we adult humans seem to constantly misplace, or dampen under the wet rag of a humdrum existence. But there it all is, smouldering away, waiting for our interest to ignite, and set it ablaze.


Note: According to some sources the species that grows here in North America should be identified as Daldinia childiae, instead of Daldinia concentrica.

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