Why Aren't Mushrooms Plants? The Surprising Truth About the Fungal Kingdom

Most of us grow up learning about two major forms of life: plants and animals. Trees, flowers, and grass are plants. Dogs, birds, and humans are animals.

So where do mushrooms fit?

Surprisingly, mushrooms are neither.

Scientists classify mushrooms as members of their own biological kingdom: Fungi. Although they may seem similar to plants because they don't move and often grow from the ground, fungi are fundamentally different in the way they live, grow, and obtain energy.

They Don't Make Their Own Food

Perhaps the biggest difference between plants and fungi is how they obtain energy.

Plants use sunlight to produce food through photosynthesis. Their green pigment, chlorophyll, captures light energy and converts it into sugars that fuel growth.

Mushrooms can't do this.

Fungi contain no chlorophyll and cannot produce food from sunlight. Instead, they obtain nutrients by breaking down organic material in their environment and absorbing those nutrients through their mycelial networks.

Rather than producing food, fungi recycle it.

Their Cell Walls Are Different

At first glance, mushrooms and plants may seem similar because both have rigid cell walls.

However, those walls are built from entirely different materials.

Plant cell walls are made primarily of cellulose—the same substance found in wood and cotton.

Fungal cell walls contain chitin, a remarkably strong material also found in the exoskeletons of insects, crabs, and shrimp.

This difference reflects how distinct fungi are from plants despite their similar appearance.

More Closely Related to Animals

One of the most surprising facts about fungi is that they are actually more closely related to animals than they are to plants from an evolutionary standpoint.

Like animals, fungi store energy as glycogen rather than starch. They also share certain genetic and biochemical characteristics that distinguish them from the plant kingdom.

Although fungi and animals followed separate evolutionary paths hundreds of millions of years ago, they remain closer relatives than either group is to plants.

The Forgotten Kingdom

For centuries, fungi were often grouped with plants simply because scientists lacked the tools to study them in detail.

As biology advanced, researchers realized that fungi represented an entirely unique branch of life with their own evolutionary history, ecological roles, and extraordinary diversity.

Today, the fungal kingdom includes everything from microscopic yeasts to towering mushrooms and the vast underground mycelial networks we've explored throughout this series.

A New Way to See Mushrooms

Understanding that mushrooms are neither plants nor animals changes the way we view them.

They're not simply unusual vegetables or forest curiosities. They're members of one of Earth's most successful and important kingdoms—organisms that recycle nutrients, support ecosystems, and continue to surprise scientists with their remarkable abilities.

The next time someone asks whether a mushroom is a plant, you'll know the answer.

It's something far more interesting.