I have a bit of a fascination with mushrooms. They’re mysterious, dangerous, psychedelic and beautiful. The things we know as fungus are only the fruiting bodies of much larger organisms in the soil. And as it turns out, for many plants soil fungi is pretty important to making the whole system work. I’ll start at the beginning.

Plants and Animals

Animals can break down, reassemble and destroy organic matter but they cannot create it. So we animals eat organic matter and rely on other things to make sure there’s enough organise matter to go around. Plants are capable of turning inorganic materials into organic materials. They make things like cellulose, proteins, and sugars from inorganic minerals derived from soil, air or water. The elements plants build with include calcium, magnesium, potassium, phosphorus, sodium, sulphur, iron, zinc, cobalt, boron, manganese, molybdenum, carbon, nitrogen, oxygen, and hydrogen.

Despite this prodigious ability, plant roots have no way to cause the break down of rocks into minerals. They must rely on whatever is in the soil already. Depending on the situation, much of what is in the soil is not in a form available for uptake into the plant. This is because plants can only take up minerals in solution from the soil. That is, as water is evaporated through the plants leaves, the plant replaces that water via the roots. The water contains all of the nutrients available to the plant, and anything not in solution is simply left in the soil. That could be organic material, rocks, or even some types of fertiliser. Even if the nutrients are there in solution, the plants can’t decide what nutrients to obtain. You see this all the time in the garden when there’s “too much” nitrogen in the soil. The plants grow fast, and depending not he plant generally turn that nitrogen into a lot of leaves rather than fruit.

Fungi

Luckily for plants, the soil contains fungi. Fungi lives in the soil as a complex interconnected mass of threads called hyphae. The hyphae are tiny - usually only one cell thick. They break down organic matter and rock particles for food, and distribute it across the network of hyphae. The network can grow to be enormous, with the size of some single organisms measured in square kilometres. Isn’t that ridiculous?

Apart from growing to insane sizes, the great thing about the abilities of fungus is that the process of breaking down organic matter and minerals can make it available to plants. Some plants and fungi form a mutually beneficial relationship known as a symbiotic relationship. The way this works is that the fungi inserts the single cell hyphae into a root hair and consumes a small amount of the plants vascular fluid. This is not generally harmful to the plant since fungi don’t survive solely on vascular fluid - the primary food for fungi is decaying organic matter in the soil. As the root grows, bark develops around the hyphae until it is subsumed into the plant. The hyphae then breaks down inside the plant, nutrients and all. This provides the plant with nutrients that would not otherwise be available to it from the soil.

Not all plants are capable of forming a symbiotic relationship with fungi. And there are certainly fungi that are destructive rather than helpful to plants.

I hope I’ve conveyed why I’m so interested in mushrooms. I find it fascinating that mushrooms are just a tiny representation of a much larger picture. To me, they are a reminder that things are not as simple as they seem. The interconnected fungus networks are a literal example of how everything is connected.