Mushrooms: Nature's Surprising Fire Hazards

Mushrooms are a type of fungus that can be found on wood. Some mushrooms are surprisingly flammable and have been used as tinder for thousands of years. The species Fomes fomentarius, often called horse hoof fungus, is a classic example of a fire-starting tinder. The dead, dry fruiting bodies of this fungus can be shaved into pieces or ground into dust to assist with friction fire spark longevity, or they can be cut into flat chips to be burned as a char cloth substitute in flint and steel fire-making. Other species of mushrooms, like Phellinus robineae, are also known to be flammable.

Why mushrooms are more flammable than plants

Mushrooms are more flammable than plants due to their unique composition. The combustibility of a substance depends on its water content, and mushrooms have a low water content compared to plants, making them more flammable. Plants typically contain a lot of water, which acts as a temperature regulator, preventing the substance from reaching the high temperatures required for combustion.

Mushrooms, on the other hand, are dry and contain a large amount of combustible material. This makes them ideal tinder for starting fires, and some species, like Fomes fomentarius (horse hoof fungus) and Phellinus robineae (cracked cap polypore), are commonly used for this purpose. The dead, dry fruiting bodies of these fungi can be shaved into pieces, ground into dust, or cut into flat chips that easily catch fire.

However, it's important to note that not all mushroom-derived substances are flammable. For example, mycelium and mycelium-biomass composites, which are made from fungal mycelium, have been found to have flame-retardant properties. Pyrolysis flow combustion calorimetry (PCFC) evaluations show that mycelium is less prone to ignition and flaming combustion than other materials like poly(methyl methacrylate) (PMMA) and polylactic acid (PLA).

In summary, mushrooms' relatively low water content and high amount of combustible material make them more flammable than plants. However, certain mushroom-derived substances, like mycelium, exhibit flame-retardant characteristics, showcasing the complex and varied nature of mushroom flammability.

Mushrooms as prehistoric fire-starters

Mushrooms have played a significant role in human history as a tool for creating fires. Before the invention of matches and lighters, our ancestors collected certain mushrooms for their flammability. This practice can be traced back to the Neolithic community of La Draga, now the town of Banyoles in Catalonia, where stores of flammable fungi were discovered.

The 5,300-year-old "Ice Man" found in a melting Alpine glacier near the Italian-Austrian border in 1991 had two mushrooms in his possession, one of which was Fomes fomentarius, commonly known as "touchwood" or "punk", used for fire-starting. This species, also called Horse Hoof Fungus, produces fist-sized polypore fruit bodies that can be shaved into pieces, ground into dust, or cut into flat chips for fire-starting. Another species, Inonotus obliquus, or True Tinder Fungus, is highly prized for its ability to ignite with a spark.

The use of tinder fungi has had a profound influence on human history. As the only species capable of creating fire on demand, humans have been able to develop related technologies, such as fireworks, ammunition, electricity generation, and internal combustion engines. Fire also enabled the cooking of food, which brought about a leap forward in dietary diversity and improved health by eliminating food-borne toxins.

While not all mushrooms are flammable, certain species, such as those found on Birch and Black Locust trees, are known to be highly combustible. These species contain a large amount of combustible material and little water, making them ideal for fire-starting.

The best tinder mushrooms

Mushrooms are more flammable than other plants due to their low water content and high amount of combustible material. For this reason, humans have been using certain types of mushrooms as tinder for thousands of years.

Inonotus obliquus, or True Tinder Fungus, is considered one of the best tinder fungi and is prized from Siberia to North America for its ability to ignite with a spark. This species can be found on birch trees in the northwoods, as well as on hop hornbeam trees.

In addition to their fire-starting properties, some tinder fungi, like Inonotus obliquus, are also known for their medicinal properties and antioxidants.

How to use mushrooms to start a fire

Mushrooms contain a large amount of combustible material and very little water, which makes them highly flammable. This is why mushrooms have been used as a fire-starting tool for thousands of years.

Find the right mushrooms:

Look for the species Fomes fomentarius, often called horse hoof fungus, tinder fungus, tinder conk, or tinder polypore. This species produces fist-sized polypore fruit bodies that are shaped like a horse's hoof and are usually grey or brown in colour. Alternatively, you can use the species Phellinus robineae, also known as cracked cap polypore, which is a shelf fungus that grows on dying or dead Black Locust trees.

Prepare the mushrooms:

Ensure the mushrooms are dead and completely dry. You can cut them into flat chips or shave them into small pieces. If you want to create a spark, you can also grind the mushrooms into a fine dust.

Create a spark:

Use a piece of flint or iron to create a spark and direct it towards the mushroom shavings or dust. You can also use a small piece of steel to create a spark, a technology that humans have been using for thousands of years.

Build the fire:

Once the mushroom shavings or dust catch the spark and begin to smoulder, gently blow on them to encourage the flames. You can then add small pieces of kindling, such as dry twigs or leaves, to build a larger fire.

Remember to exercise caution when handling fire, and always ensure you have water or another means to safely extinguish the fire.

Why some mushrooms are flammable and others aren't

Mushrooms are more flammable than other plants because they contain a large amount of combustible material and very little water. Most plants do not burn easily because they contain a lot of water, which prevents the temperature from rising high enough for oxygen to bind chemically with the fuel material. Some mushrooms, such as the Fomes fomentarius species, are particularly flammable and have been used as tinder. This species, also known as horse hoof fungus, produces polypore fruit bodies shaped like a horse's hoof. These fruit bodies can be cut into flat chips and used as a substitute for char cloth in flint and steel fire-making.

However, not all mushrooms are flammable. Mycelium, for example, has been found to have flame-retardant properties. Pyrolysis flow combustion calorimetry (PCFC) evaluations reveal that the combustion propensity of mycelium is significantly lower compared to other materials, indicating that it is less prone to ignition and flaming combustion. The release of non-flammable gases such as CO2 and H2O during the thermal decomposition of mycelium may also hinder flaming combustion by diluting the concentration of flammable gases.

The flammability of a mushroom depends on its species and the conditions under which it is growing. Some mushrooms may be more combustible due to their shape, size, or the presence of certain chemicals or compounds. Additionally, the moisture content of the mushroom can also play a role, as drier mushrooms are more likely to burn.

It is important to note that while some mushrooms can be used as a fire starter, it is crucial to properly identify the mushroom species before handling or consuming them, as some mushrooms can be toxic.

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