Daldinia concentrica, commonly known as King Alfred’s Cakes, is an inedible Ascomycete fungus which fruits all year round. They are also commonly referred to as coal fungus due to their black, dry appearance. They are widespread across the UK and can be commonly found on dead wood, particularly ash branches and beech trees. They are saprobic so feed on decaying organic matter, and are seen in most woodlands.
Anatomy:
Cap and Flesh- The fruitbodies range from 2-8 cm wide, and grow over several seasons which gives the flesh a ring formation with concentric circles of grey/ black layers. This shows the annual growth of the mushroom. They can also merge together to form larger individual mushrooms. The mushrooms initially appear brown and are very dense when young, as they age they become black and dried out. The outer layer often cracks due to its low density.
Stem- There is no stripe, instead the fruitbody is attached directly to the wood from a flat section on the underside of the fungus.
Perithecia- These are spore containing chambers which are located within the outer layer of the fruitbody. As mentioned previously, a new layer will form each season, this contains new perithecia and becomes a fertile layer. The perithecia contain asci, which contains the ascospores. Similar to other Ascomycete fungi, there is an infertile layer known as the paraphyses separating the asci. These mushrooms do not have gills or pores, the spores are contained within the system of perithecia and asci.
Asci- The asci form inside the perithecia, and each ascus contains eight ascospores. These spores are black and have an ellipsoidal to fusiform shape. The asci are cylindrical in shape, around 200µm x 10-11µm in size. Once the spores reach maturity the ascus will expand, the paraphyses will help move the asci lengthways until the tip of it is exposed. Water pressure will rise causing the ascus to burst open, the spores are forcefully ejected. This is mainly seen to happen at night and the spores disperse in wind. When there is little to no wind it has been reported that some of the spores will stick together to create a ‘rope-like’ form. These then move in ‘wave-like’ patterns that attach more spores. These spores are released from late spring to the end of autumn, however fruitbodies can be spotted all year round.
Lookalikes:
There is possible confusion with the species Daldinia fissa which is very similar in appearance and ecology except for their small size of 03-3 cm. There are many other saprophytic, black mushroom that grown in similar habitats; one such mushroom is the brittle cinder fungus, Kretzschmaria deusta. However this mushroom does not age into a black, dry fruitbody and has no concentric rings inside, so can easily be distinguished when matured.
Why the name King Alfred’s cakes?
The name ‘King Alfred’s cakes’ comes from an old story of from the 9th century when King Alfred ruled. When Britain become overrun by Vikings, King Alfred was said to have taken refuge an old peasant women’s home while he watched over the cakes. He ended up neglecting the cakes while distracted, causing them to burn. To hide his mistake and embarrassment, he scattered them across the forest. The fungus resembles the small burnt cakes, and therefore matches its common name.
Explanation of other common names:
Coal Fungus- This common name refers to the fungi’s coal-like shape and appearance. It is also a reference to Daldinia concentrica use as a fire-light. This mushroom, when black and dry with age, is ideal as a substitute to coals. They can hold a flame that’s been sparked by flint and steel, which is useful when modern technology cant be used. They have a pungent smoke and burn a lot slower, they also require constant oxygen from blowing on the fire. So while it does work as a fire-lighter, it is not very efficient.
Cramp Ball- This mushroom has no direct health benefits and is inedible, but has adopted the common name ‘cramp ball’ due to the belief that it can cure cramps. It was thought that carrying D. concentrica in your pockets or under your arms relieved cramps, such as leg aches and menstrual cramps.
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