FUNGI: THE EXPLAINER

THIS DIVERSE KINGDOM INCLUDES YEASTS, MOULDS, MUSHROOMS AND TOADSTOOLS

- DR HELEN PILCHER

What are fungi? 

Fungi are decomposing, fermenting, edible, toxic, carbon-sequestering, disease-causing, disease-curing, pollutant-busting, mind-bending, rain-generating, zombie-making marvels. They underpin almost all life on Earth, but are mostly situated underground and often overlooked.

When we think of fungi, mushrooms spring to mind, but these are just the small 'above ground' portion of the organism. Mushrooms are the fruiting body of the fungus, like the apples on a tree. Most of the fungus is hidden underground in the form of a branching network of tubular filaments called mycelium. If you took a teaspoon of healthy soil and lined up all the mycelium within it, it would stretch up to 10km.

Plant or animal?

Neither. Fungi belong to their own kingdom of life. It contains an estimated 2.2 to 3.8 million species, of which only 148,000 species or so have been described. Fungi used to be seen as simple plants, but scientists now realise that they are more closely related to animals.

Fungi come in a wide range of sizes. They can be single-celled and microscopic, like the yeast used in the beer-brewing industry, but they can also be multicellular and massive.

Spread over an astonishing 9km², the 'Humongous Fungus' in Oregon's Malheur National Forest is thought to be the world's largest living organism. It weighs hundreds of tonnes and is estimated to be between 2,000 and 8,000 years old.

How do fungi interact with plants?

Around 90 per cent of land-living plants have fungi living in their roots. A single plant can house dozens of different species. Mycorrhizal fungi, as they are known, send out fine fungal tubes that penetrate the root tips of plants. The result is a mutually beneficial relationship, where the fungi siphon sugars from the plant, and the plant receives water and nutrients in return.