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What Is Chaga? The Black Gold of the Forest Explained
- , by Noah van Knippenberg
- 10 min reading time
Chaga looks like a piece of charred tree bark. Yet this black, woody mass is part of a fungus that grows in birch trees for years. In Siberia and Northern Europe, chaga has been used in traditional drinks for centuries.
Today, chaga is mainly found in teas, powders, capsules and extracts. Interest in the fungus is growing, but what makes it so unusual? And how does that striking black mass form?
To understand chaga, we need to start with the tree it grows on.
Looking for chaga supplements? Explore our chaga capsules, powders and extract drops.
What is chaga?
Chaga (Inonotus obliquus) is a parasitic, wood-decaying fungus that grows mainly on living birch trees. In the Netherlands, this species is known as the berkenweerschijnzwam.
As a parasite, chaga lives at the expense of its host tree. The fungus grows within the birch wood and causes white rot, gradually breaking down components of the wood. This weakens the tree and may eventually cause it to die.
Chaga belongs to the family Hymenochaetaceae and is found mainly in cold, forested regions of the Northern Hemisphere.
The fungus is also known by names such as cinder conk, clinker polypore and birch conk. In Russia, it is often called tschaga, from which the internationally used name chaga is derived.
Biologically, chaga differs from most familiar mushrooms. A typical mushroom produces a fruiting body, such as a cap with gills or pores, where spores develop. In chaga, the familiar black growth is actually a sterile mass of fungal tissue, also known as a conk. This mass consists of dense fungal tissue and material from the affected tree. It is not the usual spore-producing fruiting body. That appears later, usually after the host tree has died.
What does chaga look like?
The outside of chaga looks remarkably like charcoal. It is black, hard and deeply cracked, with an irregular shape that can grow to several dozen centimetres across.
Break a piece open and you will see something quite different: a firm, rusty-brown to orange-brown interior. The fungus has no stem, cap or gills. Instead, it grows as a dark protrusion from a tree trunk, usually a birch.
However, not every black lump on a birch tree is chaga. Tree burls, damage and other fungi can also produce dark structures.
Anyone planning to collect chaga should therefore be certain of the species they have found. Its black appearance alone is not enough for reliable identification.
Where does chaga grow, and how does it develop?
Chaga grows mainly in regions with cold winters and extensive birch forests. It can be found in Siberia, Finland, Scandinavia, Canada and the northern United States, among other places.
The fungus also occurs in the Netherlands. According to the NDFF Distribution Atlas, the species is found mainly on birch trees, including in forests and wooded field boundaries.
But how does such a black mass develop on a tree?
The fungus can infect a birch through damage to its bark, for example where a branch has broken off. From that opening, the fungal tissue grows further into the wood. There, chaga causes white rot: a process in which the fungus breaks down components of the wood.
Over time, the familiar black growth can appear on the outside of the tree. This happens slowly. The fungus can remain inside a living tree for many years.
The most remarkable stage of its life cycle, however, comes only after the birch dies. A thin, brown, spore-producing fruiting body then develops beneath the bark. This fruiting body can split open the bark, allowing spores to spread to other trees.
Chaga therefore grows as a parasite on a living tree for years, but usually needs that tree to die before it can complete its sexual reproductive cycle.
Why can excessive chaga harvesting be a problem?
Chaga is not a mushroom you can harvest today and expect to see growing back the following season.
The black growth takes several years to develop. What's more, it does not produce the spores involved in the fungus's sexual reproduction. That usually happens only after the infected birch has died.
If affected trees are removed too early, that final stage of the life cycle may be lost.
Dead birch trees are more important than you might think
An ecological study published in 2024 examined the role of chaga in Estonian birch forests.
The researchers found that chaga's spore-producing fruiting body helps loosen the bark of dead birch trees.
This exposes bare wood, which can then provide a habitat for other organisms.
Nearly 50 species of lichens and related fungi were found on these birch trunks, including species of particular interest for nature conservation.
The research shows that chaga does more than break down wood. The fungus also helps create habitats for other species.
What does this mean for harvesting?
The potential ecological effects are not limited to collecting the black fungal mass itself.
Forest management also plays a role. This includes removing infected trees, clearing away dead wood and replacing mixed forests with uniform plantations.
Such practices may leave chaga with fewer opportunities to complete its full life cycle.
Harvesting a black growth does not automatically prevent the fungus from reproducing, however. The consequences depend on the harvesting method, the condition of the tree and the local ecosystem.
It would be too simplistic to say that every chaga harvest is harmful. But it would be equally unwise to assume that the supply is unlimited.
Responsible chaga harvesting is not just about how much you take, but also about what you leave behind.
For consumers, this makes the origin of chaga an important consideration.
Why is chaga called the black gold of the forest?
The nickname 'black gold of the forest' refers to chaga's dark appearance and the value traditionally placed on the fungus in Siberia and Northern Europe.
Some historical accounts date the use of chaga as far back as the 12th century. From the 16th and 17th centuries onwards, the fungus appears more prominently in accounts of Eastern European folk medicine.
Among the Khanty, an Indigenous people of Western Siberia, chaga was part of traditional folk medicine. The black fungal mass was cut into pieces and heated in water to make a dark tea. Chaga also has a long history of use in traditional medicinal practices in Russia.
Chaga also had practical and ritual uses. The Khanty mixed charred chaga with water to make a dark washing liquid, which they used to wash their hands and bodies and during cleansing rituals.
In the 20th century, chaga found another use. During the Second World War, Finnish soldiers used the fungus as a coffee substitute when regular coffee supplies were scarce.
This history helps explain why chaga acquired such a distinctive reputation. Its traditional medicinal use is part of its history, not evidence of health benefits.
What natural compounds does chaga contain?
Chaga contains various naturally occurring compounds, each with its own characteristics:
- Polysaccharides: Complex carbohydrates that, among other things, serve as structural components in fungi.
- Beta-glucans: A group of polysaccharides found in fungal cell walls.
- Betulin and betulinic acid: Triterpenes that also occur in birch trees.
- Sterols: Fat-like substances, such as ergosterol, that are important for the structure of fungal cell membranes.
- Melanin: A dark pigment that contributes to chaga's black colour.
- Polyphenols: A collective term for various naturally occurring organic compounds.
The amounts of these compounds can vary depending on the raw material and extraction method.
What are the risks of using chaga?
Chaga is natural, but that does not mean that unlimited use is necessarily safe.
One important consideration is the relatively high level of oxalates that chaga can contain.
Oxalates are naturally occurring compounds also found in various foods. Under certain circumstances, they can contribute to the formation of calcium oxalate crystals in the kidneys.
What do we know about kidney damage linked to chaga?
There have been medical reports of kidney problems following prolonged use of large amounts of chaga. These reports do not establish a generally safe amount.
Do you have kidney problems, or have you had kidney stones in the past? Speak to your doctor before using chaga.
Can chaga interact with medicines?
There is insufficient research into possible interactions between chaga and medicines.
If you take medication, are pregnant, are breastfeeding or have a medical condition, consult your doctor or pharmacist before using chaga.
Can you use chaga long term?
There is not enough research to establish a generally safe amount for daily use over several months.
At Novus Fumus, we therefore advise against using chaga continuously for months at a time.
Always follow the product instructions and do not exceed the recommended daily amount.
How can you use chaga?
Traditionally, chaga is prepared as a hot drink. Today, it is also available as powders, capsules and liquid extracts.
Chaga tea
For a traditional chaga preparation, dried pieces of the fungus are heated in water.
Because chaga is hard and woody, it is often broken into smaller pieces first.
This produces a dark drink with an earthy, slightly bitter taste.
How long chaga needs to steep or be heated depends on the product. Dried chunks, for example, require a different preparation method from soluble extract powder.
Always follow the instructions provided with the specific product.
Chaga capsules
Capsules are particularly convenient if you do not want to prepare a drink.
You take a pre-measured amount with water, without the distinctive taste of chaga.
One example is the organic McMyco chaga capsules, which, according to the supplier, contain 400 mg of chaga extract per capsule. The formula also contains vitamin C and zinc, among other ingredients.
Always check the full ingredient list and recommended dosage.
Chaga powder and extract drops
Regular chaga powder consists of dried, finely ground fungal material. Depending on the product, it can be mixed into a hot drink or smoothie.
In an extract, certain components are separated from the raw material using an extraction solvent.
Water, ethanol or a combination of extraction techniques may be used for this purpose.
Some extracts are labelled with a ratio such as 12:1. This generally means that 12 grams of dried raw material were used to produce 1 gram of extract.
A higher ratio is not automatically better. The raw material used and the actual composition are at least as important.
Liquid extracts are usually measured in drops. Check whether these products contain alcohol, as not every liquid extract is alcohol-free.
Finally: what makes chaga so special?
Chaga is an unusual fungus in several ways. It grows for years as a parasite inside living birch trees, forming a black fungal mass that does not itself produce ordinary reproductive spores. To complete its life cycle, it generally needs the host tree to die. This unusual biology makes chaga fascinating, but also shows why responsible harvesting matters.
Would you like to try chaga for yourself? Compare our chaga capsules, powders and extract drops and choose the format that suits you.
Perhaps the black gold of the forest is most fascinating when you understand how it grows – and what it takes to preserve it.
Noah van Knippenberg
Content Specialist Novus Fumus
Noah van Knippenberg writes for Novus Fumus about cultivation techniques, mushrooms, and smartshop-related topics. Drawing from his practical experience, he translates complex subjects into accessible and reliable information.
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