What Is a Fungus? A Beginner's Guide

What is a fungus? This beginner’s guide explains the fungal kingdom, how fungi differ from plants, how they feed and why mushrooms are the fruit of a hidden network.

What Is a Fungus? A Beginner's Guide

Key takeaways

  • Fungi are their own kingdom, more closely related to animals than plants.
  • They don’t photosynthesise and have chitin cell walls.
  • They feed by breaking down material and absorbing nutrients.
  • Most of a fungus is hidden mycelium; mushrooms are its fruit.

Fungi are everywhere: in soil, in wood, in the air and in our food. Yet they are often misunderstood. This beginner’s guide explains what a fungus is and how fungi differ from plants and animals.

A kingdom of their own

Fungi were once grouped with plants, but they are a separate kingdom. Surprisingly, genetic studies show they are more closely related to animals than to plants.

How fungi differ from plants

  • No photosynthesis: fungi can’t make food from sunlight.
  • Different cell walls: made of chitin, not cellulose.
  • Different feeding: they absorb nutrients from their surroundings.

How fungi feed

Fungi release enzymes into their surroundings to break down material, then absorb the nutrients. Many are decomposers; some form partnerships with plants; some are parasites. See Parasitic and Wood-Decaying Fungi Explained.

The hidden network

Most of a fungus is hidden, as a network of microscopic threads called hyphae, which together form mycelium.

Mushrooms are fruit

A mushroom is the fruiting body of a fungus, produced to release spores, rather like an apple on a tree.

Many forms

The fungal kingdom includes mushrooms and brackets, but also yeasts and moulds.

Why fungi matter

Fungi recycle nutrients, support forests and give us food, bread, cheese and more. See How Fungi Decompose Wood and Recycle Nutrients.

Continue with The Mushroom Life Cycle Explained.

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