Nature lovers or not, people everywhere can point out a mushroom when they see them. Whether they’re on the forest floor or on a pizza, these distinctive structures are easy to recognize. Folks on my nature walks are quick to call them out as we come across them, but have a lot of questions once we get to chatting. Although it sounds a little silly, the biggest question I often get is, “what are mushrooms?” After all, they are immobile like plants but can feel as flexible and soft as our own ears or noses. They come in a huge range of colors and sizes, and can grow up seemingly overnight. What kind of organism can do all of that? In this Wildlife Spotlight post, let’s take a closer look at mushrooms, what they are, and how they work.
Read more: How do mushrooms come up overnight?
Are mushrooms plants?
Let’s start with the first question most people often ask: whether mushrooms count as plants. After all, they grow out of the ground (sometimes!), don’t run or crawl or fly, and often have stems or stalks like some plants do. With a little thought, though, we can put a finger on one major plant characteristic that shrooms are typically lacking: green!
Read more: Why are plants green?
The green color in plants and tree leaves comes from a pigment called chlorophyl that they use to harvest energy from sunlight. Not seeing this on mushrooms is a major clue: if they can’t use sunlight, they certainly aren’t plants. We’ll learn below how they get their energy instead, but this clue is a major tip-off. In fact, only a close cousin to mushrooms, the lichens, are capable of harnessing energy from the sun, but that’s a different story.
A Kingdom of their own
If mushrooms aren’t plants, then what are they? The answer is more exciting than you might think. Mushrooms actually belong to their own Kingdom in the natural world. While this doesn’t make them royalty, it does mean that they are profoundly different from the plants and animals that make up most of what we consider wildlife. Mushrooms are fungi, part of a huge and diverse group of living things that are as major a category of life on earth as plants and animals, but different in many ways.
Two groups of fungi, the Basidiomycetes and Ascomycetes, produce the structures that we call mushrooms. These types of fungi are more complex than other groups of fungi in their kingdom, for example unicellular species like yeasts. Just how big a deal is a kingdom? Check out my gentle introduction to taxonomy to learn more.
Fascinatingly, fungi are more closely related to animals than they are to plants. They can grow a variety of proteins that are grown by animals rather than plants, for example chitin, which you’ll find in both insect exoskeletons and the walls of mushroom cells. The material differences between fungi and plants explain why mushrooms can have meaty flavors or textures that can’t be found in vegetables.
How do fungi get their energy?
Before we leave fungi as a group, it’s worth returning to how they get their energy, or put simply, how they eat. While plants feed themselves through photosynthesis, being what scientists call autotrophs or self-feeders, mushrooms are heterotrophs. Heterotrophs, including animals, need to break down biological chemicals to get their energy; this is why all animals have to eat, for example. Fungi are no different, although they don’t eat the way that animals do, that is, by biting food and putting it into their bodies.
Instead, fungi sit on top, or live within their food, releasing digestive chemicals to break the food down. Then, they can absorb the nutrients they want directly from the food they’re sitting on. Scientists often call this food source and anchor the substrate. Fungi can “eat” all kinds of substrates, from rotting trees to dissolved sugar and even insect bodies. Importantly, fungi like mushrooms need to find a substrate in order to settle on it, spread out their cells, and continue eating. How they do that will also help us understand what exactly a mushroom is.
Mushrooms – just the tip of the iceberg
The mushrooms that we see in salads or popping up on lawns overnight are actually only part of a living thing. Scientists and naturalists call mushrooms the fruiting body of a fungus. In other words, just like an orange or a rose blossom, they aren’t the whole story, but just part of a living thing. Specifically, mushrooms are the part of a fungus designed to help it reproduce, spread its offspring, and find a new food source.
Mushrooms contain special cells called spores which can be thought of as tiny seeds to grow a new fungus. Most of these spores are so tiny that they can travel as dust in the air, drifting around in the hopes of landing on a suitable food source, or substrate. When they do, they can quickly grow a new fungus on that spot. These spores are similar in some ways to the spores that mosses and ferns use to reproduce, unlike seed-bearing “higher plants”.
Because of this, mushrooms play the same role that fancy seeds play for plants, helping them disperse their offspring and find new horizons for growth. But if mushrooms are just a part of fungi, where’s the rest?
Read more: How plants disperse their seeds
Living webs
The main body of fungi are generally very hard to see. While mushrooms are visible and sometimes flashy, usually to attract an animal to disperse spores, the rest of the fungus keeps a low profile. It consists of tiny threads called hyphae interconnected into a network known as a mycelium. This network spreads through the substrate, digesting its food and doing its business, and is only limited in size by the available food supply.
So when you see a mushroom, you’re just seeing a flashy advertisement from a much larger fungus happily concealed within its substrate. Whether that substrate is a rotten log, the dirt of your front yard, or a dead grasshopper, there is a tangled web of living fungus inside that you can’t see. In this way, mushrooms are just the tip of the iceberg. Hidden in plain sight, sometimes enormous fungi are found that stretch out imaginations. For example, one honey mushroom (Armillaria ostoyae) fungus in Oregon covers several square miles, making it the biggest living thing on the planet!
The bottom line
So, let’s recap:
- Mushrooms are fungi, not plants or animals
- Fungi are their own phylogenetic Kingdom, consisting of thousands of species
- Mushrooms are the “fruit” of a fungus
- Any mushroom you see is just the visible part of a larger, hidden living thing
Sources and further reading
Want to learn more about mushrooms, or dig deeper into facts presented in this post? Check out this list of sources and references!
Thanks for reading about mushrooms!
Have you come across any neat mushrooms lately? Share with us in the comments! If you enjoyed this post, please support the blog by sharing this post with friends and following the blog on Social Media. If you have a post that you’d love to see, get in touch using the Contact Page. Until next time, go get to know your natural world!