Mushroom Anatomy & Bioactive Distribution
4 medicinal structures
Most mushroom supplement content treats the choice as binary: fruiting body or mycelium. But mushrooms have four distinct medicinal structures, each with a different chemical profile, including two that most consumers have never heard of.
Microorganisms 2022; Liu et al., Chin Med, 2020
< 50%
of fruiting body triterpenoids found in Ganoderma spore powder (Liu et al., 2020)
Sclerotium
the actual structure of Chaga and Poria cocos, not a fruiting body
2025
comprehensive review confirmed spores are a biochemically distinct structure (J Fungi, 2025)
Microorganisms 2022; Liu et al., Chin Med, 2020
View as image ↗Most conversations about mushroom supplements focus on a single question: fruiting body or mycelium? But that framing misses two other structures that are the primary medicinal form of several major species. Understanding the different mushroom parts and their different benefits requires knowing all four, because two of the most popular mushrooms sold today are neither fruiting bodies nor loose mycelium.
Chaga is not a fruiting body. It is a sclerotium. Poria cocos is also a sclerotium. And Ganoderma spore powder, which is sold as a separate premium product, has a distinct chemical profile from the Ganoderma fruiting body it came from. Each of these structures has a different composition, which changes what you're actually getting when you choose one over another. For the broader debate on supplement forms, see the complete guide to the fruiting body vs. mycelium debate.
Key Takeaways
- Mushrooms have four distinct medicinal structures: fruiting body, mycelium, sclerotium, and spores; most supplement content only addresses the first two
- Chaga, Poria cocos (fu ling), and Tiger Milk Mushroom (Lignosus rhinocerus) are all sclerotia, compact hardened mycelial masses, not fruiting bodies
- A 2022 review found that fruiting bodies and mycelia from the same species have meaningfully different metabolite profiles: fruiting bodies had more phenolics and indole compounds, while mycelia had more lovastatin (Microorganisms, 2022)
- Ganoderma spore powder contains less than 50% of the triterpenoids found in the fruiting body, and spore-specific glucans have a different molecular structure than fruiting body polysaccharides (Liu et al., Chin Med, 2020; Dong et al., Carbohydr Res, 2012)
- A 2025 review confirmed that mushroom spores are biochemically distinct structures with unique compound profiles not found in fruiting bodies or mycelium (J Fungi, 2025)
- In Lion's Mane, hericenones are found exclusively in the fruiting body while erinacines are found exclusively in the mycelium; both stimulate nerve growth factor but are different molecules with different properties
The Four Medicinal Structures: A Taxonomy
Most people know the cap-and-stem mushroom as "the mushroom." But that structure, the fruiting body, is only one of four structures that different species use medicinally. Each one represents a different stage or form of the fungus, and each one has a different biochemistry.
The four structures, briefly:
Fruiting body. The cap-and-stem structure most people picture. Its role in the fungus is reproduction: it carries and disperses spores. The fruiting body is the traditional medicinal part across most mushroom species. It typically contains the highest concentration of triterpenoids in species like reishi, the PSK and PSP polysaccharides in turkey tail, and hericenones in lion's mane.
Mycelium. The root-like network of thread-like structures that the fungus uses to grow through its substrate and absorb nutrients. The fruiting body grows from the mycelium. In terms of different mushroom parts and different benefits, mycelium contains different compounds than fruiting bodies: in lion's mane, the erinacines are mycelium-exclusive; in some species, mycelium contains more lovastatin (a compound associated with cholesterol metabolism).
Sclerotium. A hardened, compact mass of dense mycelium that forms as a survival and nutrient-storage structure. Sclerotia look nothing like conventional mushrooms. Chaga, the black knobbly mass found on birch trees, is a sclerotium. Poria cocos, the compact white mass that grows around pine roots, is a sclerotium. Tiger Milk Mushroom (Lignosus rhinocerus), prized in Southeast Asian traditional medicine, is also a sclerotium. Sclerotia contain different compounds than fruiting bodies, and in species like Poria cocos, the sclerotium is the entire medicinal product.
Spores. The reproductive units that a mature fruiting body releases. Ganoderma spore powder is the best-known spore supplement. Spores have their own distinct biochemical profile: research published in 2025 confirmed that mushroom spores are biochemically distinct structures with unique compound profiles not simply reducible to those of the fruiting body or mycelium.[2]
The Fruiting Body: The Traditional Standard
The fruiting body is the default reference point for most mushroom medicinal research. When a study tests Ganoderma lucidum (reishi), it is almost always using fruiting body extract. The same is true for turkey tail (PSK/krestin was extracted from the fruiting body), cordyceps militaris, and most commercial shiitake preparations.
The 2022 metabolite comparison review, which analyzed fruiting bodies and mycelia from Agaricus bisporus, Pleurotus ostreatus, and Lentinus edodes, found meaningful differences in compound profiles between the two parts.[1] Fruiting bodies contained more phenolic compounds and indole compounds. Both parts contained polysaccharides, but the concentration and structure varied. The review also found that substrate chemistry, strain, and developmental stage significantly affected compound concentrations in both forms, meaning the part is one variable among several.
For most species with established clinical research, the fruiting body is the validated form. Ganoderma lucidum triterpenoids (ganoderic acids) are highest in the fruiting body. The polysaccharide complex PSK from turkey tail, which has the most extensive human clinical trials of any mushroom compound, was derived from the fruiting body. If you're trying to match a supplement to the research, the fruiting body preparation tends to be the closest equivalent for most well-studied species.
Mycelium: Different Compounds, Not Just a Different Form
Mycelium contains different compounds than fruiting bodies from the same species. The 2022 metabolite comparison found that mycelia from the same mushroom species contained more lovastatin, a compound associated with cholesterol metabolism.[1] The fruiting bodies had higher phenolic content.
The most species-specific example is Lion's Mane. In Hericium erinaceus, the two compound families that stimulate nerve growth factor (NGF) production are found in different parts of the plant: hericenones are found exclusively in the fruiting body, while erinacines are found exclusively in the mycelium. Both compound families support NGF production, which is associated with nerve cell maintenance and regeneration. But they're chemically distinct molecules, and research indicates that erinacines cross the blood-brain barrier more efficiently than hericenones. This means the "which part is better?" question has a different answer for Lion's Mane depending on whether the intended application is general immune support or neurological benefit.
One important caveat about mycelium supplements: some commercial mycelium products are grown on grain substrates (typically oats or brown rice) and are processed without removing the grain from the mycelium. A product made from mycelium-on-grain will contain starch from the grain alongside the fungal compounds. This contamination issue is addressed in more detail in Fruiting Body vs. Mycelium on Grain: The Debate That Defines Mushroom Supplement Quality.
Sclerotia: The Missing Category Behind Chaga and Poria
This is the category that most mushroom supplement content ignores entirely.
A sclerotium is a hardened, dormant mass of dense mycelium that a fungus forms as a survival structure. Sclerotia store nutrients, resist desiccation, and allow the fungus to survive unfavorable conditions. They're typically compact, dark-colored, and form inside or on a host substrate. They look nothing like conventional mushrooms.
Chaga (Inonotus obliquus) is a sclerotium. It grows as a black, woody mass on the bark of birch trees in northern climates. Chaga rarely produces a conventional fruiting body. The supplement product sold as "Chaga mushroom" is the sclerotium, not a fruiting body. This distinction matters because Chaga's chemical profile is shaped by two factors most fruiting body mushrooms don't have: the dense sclerotial tissue itself, and the birch host tree. Some of Chaga's most studied bioactive compounds, including betulin and betulinic acid, don't come from the fungus. They come from the birch tree, absorbed into the sclerotium during the decades of parasitic growth.
Poria cocos (fu ling, sometimes called Indian Bread) is also a sclerotium. It forms as a compact white-to-brownish mass on pine roots. Poria cocos has one of the longest documented histories in traditional Chinese medicine, used continuously for over 2,000 years. Its primary triterpenoids, the pachymic acid class of lanostane triterpenoids, are found in the sclerotium and are structurally distinct from the ganoderic acids of reishi fruiting bodies. When researchers study Poria cocos for sleep effects, anxiety, or immune modulation, they are working with sclerotium extracts.
Tiger Milk Mushroom (Lignosus rhinocerus) is a third example. Revered in Southeast Asian traditional medicine for respiratory conditions, it also forms its bioactive material in a sclerotium buried in the substrate. A comprehensive review documented the ethnomedicinal uses and pharmacological evidence for Lignosus sclerotia, establishing that the sclerotium is the primary medicinal structure for this species.[4]
For a deeper look at sclerotia as a category, including how their biochemistry explains Chaga's unique profile, see Sclerotia in Medicinal Mushrooms: The Chaga and Truffle Connection.
Spores: A Different Chemical Profile Than the Fruiting Body
Ganoderma spore powder is marketed as a premium form of reishi. This positioning suggests spores are a concentrated or superior version of the fruiting body. The chemistry tells a different story.
Liu and colleagues compared triterpenoid content in 12 batches of Ganoderma spore powder (both cell-wall-broken and unbroken) against fruiting body samples using high-performance thin-layer chromatography and mass spectrometry.[5] The spore powder contained less than 50% of the triterpenoids found in the fruiting body. The conclusion: triterpenoids should not be used as a quality marker for Ganoderma spore powder because the spore powder is a different product, not a concentrated version of the fruiting body.
But that doesn't mean spores are without value. It means they're different. Dong and colleagues isolated a water-soluble beta-D-glucan from Ganoderma spores and found it had a distinct molecular structure from the polysaccharides in the fruiting body.[3] The spore-specific glucan was not simply a less potent version of fruiting body polysaccharides; it was a structurally different compound.
A 2025 review of bioactive compounds in mushroom sexual spores confirmed that spores are biochemically distinct structures with compound accumulation patterns governed by different molecular mechanisms than fruiting bodies.[2] Spores are not smaller versions of the cap and stem.
What This Means When Reading Supplement Labels
Understanding the four-structure taxonomy changes how you read a product label.
"Fruiting body extract" means the cap-and-stem structure, typically the most studied form for most species. For reishi, turkey tail, shiitake, and most other common medicinal mushrooms, this is the part the research used.
"Mycelium extract" can mean several different things depending on how it was produced. Mycelium extracted from a submerged liquid fermentation system and then dried is different from mycelium-on-grain that is dried with the grain substrate intact. The former is a cleaner fungal product; the latter contains starch.
"Chaga extract" is always a sclerotium extract, regardless of how the label reads. There is no commercially available Chaga fruiting body product.
"Ganoderma spore powder" is a different product from Ganoderma fruiting body extract. The triterpenoid content is lower; the spore-specific polysaccharides are different. A product positioning spore powder as superior to fruiting body extract based on triterpenoid content is making a claim the chemistry doesn't support.
For a compound-by-compound breakdown of where specific bioactives are found across all four structures, see Mycelium vs. Fruiting Body vs. Spore: Where Do the Bioactives Actually Live?. For how substrate affects bioactive distribution within mycelium, see Secondary Metabolites in Mushrooms: The Compounds Beyond Polysaccharides.
The Bottom Line
Mushrooms have four distinct medicinal structures: fruiting body, mycelium, sclerotium, and spores. Most supplement content ignores the last two. Chaga and Poria cocos are sclerotia with distinct chemical profiles shaped partly by their host substrates. Ganoderma spore powder contains fewer triterpenoids than the fruiting body and has spore-specific polysaccharides with different structures. In Lion's Mane, the two main nerve-growth-factor-stimulating compound families are split between structures, with hericenones in the fruiting body and erinacines in the mycelium. Understanding which part a supplement uses is necessary for connecting it to the research.
Frequently Asked Questions
Sources & References
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