What Is a Mushroom?

Mushrooms have been a delicacy for ages. For even longer, they’ve been used in the art of medicine. Whether used directly in compresses or poultices, or through teas and tonics, mushrooms are a major player in the health world and display many benefits.

But today we’re not here to talk about the benefits of mushrooms. Instead, we’re more curious about what they are. What makes something a mushroom? Is it a plant, a vegetable? Do all mushrooms have the same parts? How do they get their nutrients?

In other words, WHAT is a mushroom??

 

They’re a Fun-Guy

Yes, mushrooms are fungi. If your mom and dad told you that mushrooms are vegetables, they were wrong. In the culinary world, mushrooms are seen more as fruits than vegetables, because mushrooms contain their spores (think seeds). Actually, though, mushrooms are neither fruit nor vegetable. In fact, they’re not plants at all.

If you remember science class in middle school/junior high, you’ll recall that there are 5 Kingdoms of Living Things -- animal, plant, fungi, protist, and monera. Fruits, vegetables, grains, and herbs are the plants humans eat,[1] and thus belong to the Plant Kingdom. Mushrooms, however, stem from a type of fungi called basidiomycetes. But what does that mean?

The biggest differences between plants and basidiomycetes are their structure and means of obtaining food. Regarding structure, the cell walls of plants consist of cellulose, while fungal cells walls are mostly chitin. Plants get their nutrients (except for minerals) through the process of photosynthesis, which requires the presence of chlorophyll[2], while fungi “absorb” foods from their environment and then digest them.

There are millions of species of fungi, the most common being mold, yeasts, mildews, truffles, and basidiomycetes. Mushrooms are not organisms, but rather the “fruits” of the latter. What makes these organisms unique is their anatomy.

 

Mushroom Anatomy.

What we call a “mushroom” is the “fruiting body” of the basidiomycete organism. The other major part, which remains beneath the ground and can live for thousands of years, is called the mycelium. The fruiting body and mycelium work together to enable a basidiomycete species to spread and grow while providing healing – and sometimes delicious nutrition -- for us.

However, a complete basidiomycete is more than its mushroom and mycelia. Let’s take a look and see how these other parts support the organism’s overall lifecycle.

The Cap is the head, or top, of the mushroom. Some heads look like umbrellas, or “buttons,” while the shapes of others, like Turkey Tail, lead to their names. Some lack typical stems or caps. Lion’s Mane, for example, has fine rows of sharp, icicle like teeth that bring to mind a male lion’s head of hair, while Chaga resembles a lump of coal. The cap’s purpose is to house and protect the organism’s gills, pores, or teeth.

labelled illustration of matured mushroom showing where to find the mushroom's Cap, Gills, Ring, Stem, Cup, and Mycelium.

The Gills, Pores, or Teeth are like little storage units inside or under the cap. These units produce and store the organism’s spores, or “seeds.” Typically, the caps of young mushrooms are tight-knit and covered by a veil. As the mushroom matures, the caps spread out and the veils disintegrate so that spores will drop to the ground.

The Ring is what remains of the partial veil after the gills break through. It is sometimes called the annulus or skirt.

The Stem, or Stipe, is the cylinder like structure that gives the mushroom its height. As a mushroom matures, the cylinder continues to grow longer, thus helping the mushroom reach the height at which it can most effectively spread its spores over the surrounding region.

The Volva, or Cup, is what remains of the membrane (the universal veil) that protected the entire mushroom during its development. As the fruiting body sprouts, it shoots upward through the volva.

The Mycelium is, more or less, a basidiomycete’s root system. It is comprised of several thin filaments (hyphae) that may grow in the soil, decaying trees, etc. Just as a plant’s roots collects minerals, the fungal mycelia collects nutrients to pass on to the mushroom so that the mushroom can grow and mature. In a successful life cycle, the spores dropped by the mushroom become a new mycelium.

Mycelia can live for thousands of years, connecting and intertwining with new generations of the same organism. The largest and oldest mycelium in the U.S. is in Oregon – it is around 3.4 miles wide and may be up to 8,000 years old! Mycelia are of vast importance in nature, aiding in the decomposition of dead plant material.

The Hyphae carries the mushroom’s genetic makeup and is the mycelia’s starting component. In short, spores result in hyphae, which then produce mycelia. From the mycelia, the beginnings of the mushroom sprouts and soon pushes above ground. The mushroom is the basidiomycete’s fruiting body that is used as food, dietary supplements, and medicine. As the mushroom grows, its stem, gills, spores, and cap develop. When it is fully grown, the gills open to drop the spores and the entire cycle starts again.

 

Labelled illustration of Mushroom lifecycle, showing growth stages of Spore to Mycelium to Egg to baby mushroom to adult mushroom.

 

Are All Mushrooms the Same?

No two mushrooms are alike. Each can have wildly different appearances from the next. While they all share certain nutritional similarities, each also contains at least a few unique phytochemicals and secondary metabolites not found in others. These are the factors that “fine tune” their values as supplements. While the fruiting body is the part of the basidiomycetes you normally want for food or as a dietary supplement, Chaga is an exception. You can learn more about it in our Chaga Story!

 


 

Sources

[1] https://www.merriam-webster.com/dictionary/vegetable

[2] https://biologydictionary.net/plant/

August 09, 2021

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