Outside of a handful of similarities, fungi are biologically very different from plants. They don’t create their food, don’t occupy the same part of the food chain, their cell walls are made from different materials, and even if they may look similar, they consist of different “body parts”.
To add to that, their only common ancestor is the same one they share with animals as well.
How did the misclassification happen?
Early observers saw them growing the same way as plants, and that was it. As the scientific methods developed and we got to study the world on a molecular level, we managed to learn more about it.
For example, renowned paleontologist and evolutionary biologist Stephen Jay Gould discovered that there is no such thing as fish. Everything that swims is far more biologically related to animals on land that they are related to each other.
In the same way, scientists took a closer look at fungi and saw that they have very little in common with plants.
Nomenclature
Even though they are not plants, their names are still governed by the International Code of Botanical Nomenclature. Yes, that means that mushrooms are still named in the same way as other plants.
But, beyond their “botanical names”, most of the other terminology comes from the animal kingdom.
What separates fungi from plants?
Though they don’t look much different from each other, scratch the surface and there you’ll find the truth. Here are the main 8 differences between plants and fungi.
Different cell wall components
Plant cell walls contain cellulose, while fungi are composed out of a substance called chitin.
Chitin is a large polysaccharide that can be found in insects, fish, invertebrates, and of course fungi. It’s made from modified glucose and is rather versatile – it can produce anything from delicate insect wings to tough shells in crustaceans.
In fungi, citing creates a rigid cell wall that allows the organism to keep its shape. This is one of the reasons why mushrooms can push through layers of other plants as they grow.
To chlorophil or not to chlorophil
Not to chlorophyll.
Chlorophyll is a green pigment that exists in plants, algae, and some types of bacteria, but not in fungi. It’s responsible for the color of the plants, but also helps absorb light for photosynthesis.
It would not be far off to say that it’s the reason why life on Earth is possible. However, there is not even a smidgen of it in fungi.
Digestion
Fungi digest their food, while plants don’t.
They don’t do it in the same way as animals, though – as in, consume it and then process it within a digestive system. Fungi release enzymes that pre-digest the food, after which they “absorb” it.
As such, their eating habits are quite in between both plants and animals.
Roots, stems, and leaves
Fungi don’t have any.
Though you may have heard them being called mushrooms stems before, they are actually something named stipes. Depending on the type of mushroom, they may look like stems or stalk, and their purpose is to support the cap. Species of fungi that have them are classed as stipitate.
They are composed of sterile hyphal tissues. Hyphae are long branches of fungus and are a main mode of growth, but n the case of the stem, they can reproduce.
When it comes to natural selection, taller stipes aid in spore dispersal. But, they are not crucial when it comes to the mushroom’s ability to reproduce
Unlike the stems of small, “ground-level” plants, stipes are an important tool in identifying the species of mushroom (as well as if it is poisonous or not).
Make or take food
Plants are autotrophic while fungi are heterotrophic. This means that plants make and fungi take their food from other sources.
Plants’ ability to create their own food is all due to photosynthesis. The Sun’s energy is the driving force behind their ability to convert water and minerals from the soil into nutrients and starches.
And as discussed, fungi digest their food first, then consume it.
Types of reproductive cells
Fungi mostly reproduce through spores, while plants do so through seeds and pollen.
Spores are suitable for both sexual and asexual reproduction. They are dispersed into the environment and are can survive for a long time before they take root.
There are multiple types of spores, and each one of them has a unique way of how they give birth to a new organism.
Place in the food chain
There are 5 main trophic levels in the food chain, and each species finds its place based on how they consume energy. The first level is producers, while all of the others can be classified as consumers. They include herbivores, carnivores, and omnivores.
Decomposers don’t belong to a specific level since they feed off all dead animal and plant material.
So, this puts plants in the first level as primary producers, while fungi are winning the food chain game by being decomposers and eating everyone.
Food storage
Both plants and fungi can store food, but the former does it as starch, while the latter does it as glycogen.
This is where fungi become more similar to animals. Even humans store glycogen in the liver – on average enough to last for around two days.
Both fungi and bacteria benefit from their ability to store energy as glycogen in environments that are low on nutrients. On the other hand, rich glycogen stores are associated with massive and rapid fungal and bacterial growth. This is where once more fungi show why they are a kingdom of their own since an animal that has to deal with excess food doesn’t start multiplying, but begins to multiply its fat deposits.
How are fungi similar to plants?
They are both eukaryotic and they don’t move.
Though the latter is pretty self-explanatory, the former refers to the type of cells the organism is composed of. The term translated from Greek means “good kernel” which in a way describes what is going on inside those cells. The nucleus is enclosed in a shell or an envelope, unlike in prokaryotic cells where the nucleus is directly embedded in the cytoplasm.
Animal cells are also eukaryotic, but they lack the same cell wall that you can find in plant and fungi cells.
To make things interesting once more, animal and fungi eukaryotic cells belong to the same group called opisthokonts, while the plants are in a completely different branch of the family.
If fungi are not plants, are they animals then?
No, even though they have a lot of things in common.
As mentioned, animal cells don’t have walls. Also, animals move around, reproduce sexually (generally), and have a very simple life cycle. Their bodies are composed of complex systems of organs, each containing vastly different types of cells and tissues.
Animals also have a fully developed nervous system and can react to external stimuli very quickly, while fungi are very slow to react and adapt.
Both life forms are heterotrophs, which means they need complex nutrition to survive, and both are capable of storing carbohydrates as glycogen for future use. However, animals ingest their food, while fungi absorb it from their host or soil.
Speaking of hosts, a lot of species of fungi are parasites and can even latch onto animals (like Ophiocordyceps Unilateralis, aka zombie ant fungus). In most cases, a parasite fungus is most likely to kill its host, but they also often form symbiotic relationships with plants.
What came first, fungi or plants?
Plants are just about 9 million years older than fungi. That’s in terms of when they started separating from animals. For any sign of a mutual ancestor, one must dig through the primordial ooze.
Some DNA evidence suggests that the common ancestor of the entire fungi kingdom may be about 600 million years old. As with all other life, it probably lived in water before it moved to conquer the land.
That move may have started about 500 million years ago, though fossil record shows them spread all over the world just a mere 100 million years later. There’s also a reason to assume that about 250 million years ago fungi were the most dominant life form on the planet considering how abundant they were at the time. Right after dinosaur extinction, there seems to also be a spike in the number of fungi in comparison to other species.
In 2019, scientists discovered a fossilized fungus in the Canadian Arctic that is assumed to be a billion years old. If their calculations are correct, that would change everything we’ve learned until now,
Do fungi need sunlight?
No. As mentioned, they don’t have chlorophyll in their cell walls and don’t engage in photosynthesis. In fact, many species of fungi thrive in shade.
Do fungi need a special environment to grow?
Unlike plants, fungi don’t have a set of specific environmental requirements that are mandatory for every species. Some prefer a moist environment, some prefer to stay dry. Some like the dark, while some thrive in the sunlight.
How do fungi reproduce?
Though we already saw that fungi reproduce both sexually and asexually with spores, let’s get into some detail of how it happens.
Asexual reproduction
This method is comparable to the way plants reproduce by planting seeds.
In short, the fungus releases the spores, they spread into the environment and seek suitable habitat. Once they settle, they germinate and form a new mycelium, aka the fungus “root”.
We place fungi in different groups based on how they store the spores (amongst other things). For example, Zygomycota (often found in soil and decaying plants and animals) have little sacs that burst to disperse the spores.
On the other hand, Ascomycota and Basidiomycota don’t have such sack and produce spores directly from the hyphae. Ascomycota fungi are the ones that are responsible for fungal infections, while a Basidiomycota is more likely to end up on your plate (edible mushrooms).
Sexual reproduction
This form of reproductions can be described as a step up from spore dispersal. In this case, the hyphae of two individual fungi join and combine in a process called plasmogamy. Then, another process called karyogamy takes place, and at this time the DNA of the two individuals mixes and combines.
Spores that come out after these processes have double the normal number of chromosomes. Then, in a (yet another) process called meiosis, new spores divide to create spores with a normal number of chromosomes.
After that, we are going back to basics – the spores disperse and settle in fitting habitat.
All species of fungi that produce sexually can also produce asexually. This includes already mentioned Zygomycota, Ascomycota, and Basidiomycota, and each produces a different spore structure.
What are the major types of fungi?
The latest classification divides the entire fungi kingdom into 7 phyla, 10 subphyla, 35 classes, 12 subclasses, and 129 orders. When we say type, we refer to the phyla and their very recognizable differences.
Ascomycota
The largest phylum that contains the most species of fungi. All species that belong here have a spore sack that burst once they are ready to be dispersed into the environment.
All types of yeast (the ones used in bread, beer, cheese, and medicine production) originate here, as well as several other types of mushrooms, truffles, molds, etc.
Basidiomycota
This is the phylum that includes the most recognizable fungi: mushrooms. Some of their plant-like characteristics were the reasons fungi were mistaken for plants for centuries.
However, it’s not all about the ballad of stems and caps – this group also includes multiple grain pathogens, some that attack humans, and even rust.
Chytridiomycota
The fungi in this group are called chytrids and they consume keratin and chitin. Some species are parasitic, and some even attack animals. For example, this is the phylum that includes Batrachochytrium dendrobatidis that latches onto frogs and other amphibians.
They are aquatic, which means that water is their natural habitat. Also, it’s considered that this type of fungi may be one of the earliest to diverge from other kingdoms.
Blastocladiomycota
The members of this phylum feed off of decomposing material. They are able to consume pollen, cellulose, keratin, and chitin as well.
Most of the species in this group are parasites. The most recognizable on to us may be the Physoderma maydis, a fungus that latches onto corn and maize, and caused the brown spot disease.
However, because of their ability to consume different material, Blastocladiomycota have an important ecological role.
Glomeromycota
If the name of this type of fungi makes you think of conglomerates, you are not far off. They form these rather pretty webs that resemble something you would find in a presentation on communication and networking.
They form symbiotic relationships with their hosts. They latch onto hosts with fine root systems in rich soil that coexist with other types of fungi already. They pay their host plant back by making them better at responding to environmental stimuli and stresses while helping the other fungus to obtain carbohydrates from the host.
Microsporidia
This phylum contains single-cell spore-forming parasites. They infect animals and protists, but when they get to humans, the infection is called microsporidiosis. The main characterization is the enlargement of the infected tissue, and any part of the body may be affected.
The diseases caused by microsporidia are rarely lethal, but may often be debilitating.
There are about 1500 species that are officially named, while it’s believed that over a million belong to this type.
Neocallimastigomycota
This is a small phylum of anaerobic fungi. They are often present in cellulose-rich environments – anything from the digestive systems of larger herbivores to landfills, even being found in humans. Cows, deer, and other ruminants rely on this type of fungi to digest fiber.
They were officially recognized in 1975 as fungi and, though they were discovered much earlier than that, it was originally believed they were protists – organisms that are neither animals, plants, or fungi.
Are all mushrooms edible?
As someone wise once said, yes but some you can eat only once.
All joking aside, a lot of mushrooms are seriously poisonous and other species of fungi may cause serious illnesses and even death. Assuming you are not planning to go foraging for mold, picking up random mushrooms in the wild is not the best idea ever.
Are all fungi harmful?
Not necessarily. Most are not dangerous to both the plant and animal life. It’s very similar to how not all bacteria cause serious illnesses.
Are there fungi in or on the human body?
Considering that fungi don’t always have to be portobello-size, there’s a chance that you are right now sharing your body with a fungus or two. In fact, there are even a few species that can co-exist with us without causing us major health issues. Well, if our bodies are healthy, to begin with.
For example, Malassezia is all over us and generally doesn’t trigger our immune systems. Though, it can be problematic for those with auto-immune illnesses or eczema.
Currently, there is no evidence to suggest that we may have any benefits from the fungi that are not making us sick. However, it’s still a young field of research and something that we’re trying to figure out this time around.
