King Alfreds Cakes

What are King Alfred’s cakes, cramp balls & coal fungus?

King Alfred’s cakes (Daldinia concentrica), also known as cramp balls and coal fungus, are a type of inedible fungus. They are most commonly found in broadleaf woodlands. You will see them growing in groups, on dead or dying trees, most often, but not confined to, fallen Ash and Beech branches. King Alfred’s cakes are quite common in the UK but can also be seen in parts of Europe and North America. 

Where does the name come from?

There is a legend that the Anglo Saxon King Alfred was trying to escape the Vikings who were invading Britain. During his escape, a pheasant women gave him shelter. She asked him to be in charge of watching over her cakes, baking by the fire. Unfortunately, he fell asleep and the cakes were subsequently burnt. It is thought that out of embarrassment he then scattered the cakes in the forest to hide his mistake. The fungus – which has the appearance of small burnt cakes – takes its name from this story.

The other name for King Alfred’s cakes is cramp balls. It was believed that carrying the fungus in your pocket would help prevent cramp. There other common names of coal fungus and carbon balls come from their historic use as fire starters (see below).


King Alfred's Cakes
King Alfred’s Cake coal like appearance

King Alfred’s cakes’ fruiting bodies are small, hard rounded balls of fungus. They look a bit like round lumps of smooth coal. Each ‘cake’, which is formally referred to as the stroma, varies in size from 2-10cms wide. When the fruiting bodies first appear they are a reddish-brown colour, darkening to a black, shiny ‘burnt’ appearance as they get older.

When the fruiting bodies are cut open you can see the spores. The flesh inside is hard and concentric rings of silver and black can be seen within. These rings are like those in a tree, with each circle representing a year’s growth! This also explains the Latin name of Daldinia Concentrica. An easy way to spot this fungus is to look for some wood that looks like it has been burnt in certain places. This is because the fungus releases spores beyond its outer surface, which can leave a black spore print 3cm wide around the fungus.



The dark black King Alfred’s cakes are a great source of natural tinder for fire lighting. Evidence of this dates back to the archaeological excavation of a Spanish settlement from 7,000 years ago. During the excavation this fungus was found alongside other different ‘tinder’ fungi.

King Alfred's Cakes
The concentric rings

To be used as a source for fire lighting they need to be completely dry but can then be ignited easily with a traditional flint and steel. It is best to get the spark on the inside of the surface, so either break it open, or make a small hole. Once ignited, blow gently to get the heat to spread. Much like charcoal, they burn slowly, but have a much stronger pungent smoke. Due to the length they smoulder for, it is thought that this fungus, as far back as the stone age, was used to transport fire whilst travelling. If they had a King Alfred’s cake, and some dry tinder with them, then they knew they could always start a fire, even if there was no dry wood available. What great initiative and a powerful survival tool!

However, do be aware of this if using them yourself – they are quite hard to extinguish and smoulder for a long time.


In addition to their fire-lighting properties, they play an important role within nature. King Alfred’s cakes accelerate the decomposition of fallen branches. As they are fire-loving they are also some of the first species to grow after forest fires. They can grow on burnt wood and hence love the fire debris. It is important we have fungi like this, as they are paramount to helping the recovery of the landscape. Many types of small insects and animals also use the inside of King Alfred’s cakes as their home, and the caterpillars of certain moths also feed on them. They are NOT edible for humans.

Who knew fungi could be so interesting and vital to not only nature, but also for mankind in the past? They are fascinating to see, and if you keep your eyes peeled when next walking in woodland, you are bound to see some. I spotted some on these two walks in Berkshire: ‘Ashampstead, Yattendon Walk’ and ‘Donnington Castle, Bagnor, Winterbourne’. They live for many years, and therefore can be spotted all year round – so no excuse to not get searching for them!

If you want to know even more about King Alfred’s cakes, then visit: First Nature.

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