The Anatomy of a Mushroom from "Root to Fruit"

Mushrooms are wonderfully complex and powerful. Their effects on our immune systems and brain nerve growth are only now being explored with actionable curiosity by Western science. Traditional Chinese Medicine and indigenous cultures worldwide have celebrated medicinal mushrooms for centuries. Whether an edible mushroom like porcini or a beautiful beast like a puffball, fungi do indeed rule the earth.

What makes a fungus a type of mushroom? Well, fungi don’t share one precise taxonomic definition that relates to the body of a fungus. The term mushroom has been applied to everything from gilled mushrooms to boletes to polypores. According to PG Miles in Mushrooms: Cultivation, Nutritional Value, Medicinal Effect, and Environmental Impact, “ mushrooms don’t have one precise taxonomic definition. Because of this, there are over 14,000 identified species of mushrooms. The kicker? We discover more new mushrooms every day.

This guide focuses on the different parts in the anatomy of mushrooms like lion’s mane, morel, shiitake, turkey tail, chanterelle, maitake, and more. No two mushrooms are alike; this is a guide to the general physical mushroom structure.

The basic mushroom anatomy

A mushroom is made up of eight common parts. From the top to the bottom, they are the cap, gills or teeth, spores, a ring or skirt, the stem or stalk, the volva, the basal bulb, and mycelium.

These organic matter parts are categorized into two parts of the mushroom: the fruiting body and mycelium.

The difference between the fruiting body and mycelium

The fruiting body of a mushroom is made up of its reproductive parts, mainly the cap and the stalk. These are the above-ground components of the mushroom. The mycelium is comprised of mycelial fibers underground that support the fruiting body.

Studies in Western science have shown fruiting bodies to be the purest, most beneficial parts of the mushroom, but recent studies are giving new life to the benefits of mushroom mycelium, especially when it comes to nerve growth factor. The benefits that we seek mushrooms for are beta-glucans and polysaccharides and these are found in abundance in the fruiting bodies.

The fruiting body

The mushroom cap

Mushroom caps are the part of the mushroom most commonly seen above ground. Also known as a pileus, caps come in all shapes and sizes from bell to flat. Caps can curve inward at the center in a concave shape and even have teeth, like the long lion’s mane strands that contribute to their name.

The cap is where the reproductive part of the mushroom is. These commonly consist of gills, like oyster mushrooms, but can also consist of pores like porcini or teeth like lion’s mane. The margin, or edge of the mushroom, refers to the ends of the mushroom cap. This is what you can easily spot on the forest floor.

The mushroom stalk

Also known as the mushroom stem or stipe, this is the base of the mushroom that connects it to the ground and where some species of mushrooms have their ring. Button mushrooms like cremini and porcini usually have edible stems

Gills

Usually found on the underside of the cap, mushroom gills are also called pores or lamellae. The gills create the spores of the fruiting body. Not all gills look alike and no two varieties have the same gills.

The tubes of a mushroom are where the spores come from in some mushrooms. They can also replace gills in some varieties. Mushrooms like turkey tail and cordyceps have uniquely designed parts of the fungi to accommodate tubes.

Spores

The gills release spores, or seeds. These are the reproductive cells that the mushroom cap sheds. Mushrooms are so prolific, they release spores into the air by the thousands every day. Their goal is to land somewhere they can germinate and make more mushrooms.

When a spore settles on fertile territoriy, hyphae grow and start to gather food. This is one of the ways that mushrooms are more closely related to animals than plants.

When one spore’s hyphae meets another spore’s hypae, the mushroom fruiting body is able to grow. Mushroom spores don’t always make their parent spore based on the partner spore. This is how new fungi develop all over the planet.

Optional: Ring, volva, and bulb

The ring

Not all mushrooms have rings, volvas, and bulbs. These elements grow with some varieties to protect the gills and spores during mushroom growth.

The ring is the soft membrane that forms on the stem, usually under the cap. This is also called a partial veil and not all mushrooms shed this leftover tissue as they grow taller.

The volva

Like the ring, the volva is leftover tissue from the universal veil that grows for protection. While the ring grows usually mid-stalk, the volva usually grows in a cup shape around the base of the mushroom stalk.

The bulb

At the bottom of a mature mushroom, some varieties have a chunky structure. This is where the mushroom came from! The spores that landed and released hyphae underground produce the bulb to protect the mushroom egg as it grows.

Mycelium

The motto of mycelia is best related to one of the iconic quotes from Antoine de Saint-Exupéry’s The Little Prince: “What is essential is invisible to the eye.”

Mycelium is the thread-like web of hyphae that connect and reproduce. The hyphae produced by germinated spores make up mycelium underground. Mycelium aren’t essential to just mushrooms. This network connects plants with each other and research has even found that related trees can supply nutrients back and forth to each other through mycelium.

The lifecycle of a mushroom

The gills release spores into the air each day. If the spores land in fertile soil to its liking, it will grow hyphae underground. If one hyphae meets another hyphae, mycelium will grow. If the two hyphae mate successfully, a fruiting body will grow above ground. The fruiting body will release spores when it’s mature, continuing the mushroom life cycle.

Mushroom classification

Before 1969 in Western science, there were only two classification systems: animals and plants. Anything that grew from soil and had rigid cell walls was a plant. Mushrooms, by that definition, were considered plants. Mold, mildews, and other varieties of what we now call fungi weren’t clearly classified. This in-between state, neither animal or plant, is what defines mushrooms in the Western world until the last few decades. So, what changed?

In a 1969 Science magazine article titled “New Concepts of Kingdoms of Organisms,” ecologist Robert Whittaker proposed a five-kingdom classification system. As professor Tom Volk told LiveScience, “Mobility and the method of gaining nourishment [was] the criteria for a system of classification.” Whittaker’s proposed system highlighted the relationship between animals and plants, and where fungi differed from its “rooted” plant siblings. This system has evolved in Western science to break apart fungi into further kingdoms, such as molds and mildews.

Why are mushrooms related to animals more than plants?

There are so many reasons that range across each species of mushroom, but these are the two pivotal reasonings that Whittaker introduced in 1969.

Two-layered cells

Fungi, according to Van Nostrand’s Scientific Encyclopedia, Vol 1, 10th Ed., have two-layered cells: an inner cell membrane and an outer cell fungal wall. These are the two layers that make mushrooms more aligned to animals than plants.

Nutrient absorption

Plants perform photosynthesis. Photosynthesis is the process that plants and other plant-related organisms synthesize foods through carbon dioxide and water. Plants use the sun to self-feed, essentially, and it’s this process that also gives plants that beautiful green.

Animals can’t do this and need to feed. Beings that need to feed are known as heterotrophs. Fungi are also heterotrophs and need to absorb, or digest, nutrients. That’s why the parts of a mushroom are so different from plants and so similar to us.

The future of mushrooms

We’re only beginning to understand the impact of mushrooms on the planet. Fungi are regenerators. They succeed in places of blasted landscape and create life from ruin. One of the small anecdotes from Mark Monroe’s groundbreaking Fantastic Fungi is the tale of the oil slick experiment.

Of three oil spill piles, one was left to its own devices as a control. One was fertilized through traditional means. One was left to the fungi team led by Paul Stamets. The one with mushrooms not only created life the fastest, but invited it back in. Plants, insects, and birds were frequenting the oil spill full of fungi. That is the future of mushrooms we embrace.

Growing mushrooms is one way to embrace mycology. Because they are famous decomposers, you can grow almost any type of substrate to practice. Just remember that mushrooms are bioaccumulators, so whatever you choose to grow your species on, it will inhabit some of those health benefits, for better or worse.

If you want to stick to foraging, check out our guide to the best mushroom identification resources on the web.