All you need to know about fungi, including how it reproduces
Fungi is all around us if you know where to look – mushrooms in forests, mould on bread – but many are inconspicuous or invisible to the naked eye.
This might explain why they’re so often overlooked and were once grouped with plants, despite being a kingdom with their own branch on the tree of life.
What’s the difference between fungi and plants?
Like plants, many fungi grow in soil, can’t move around and their cells have walls (reinforced by cellulose in plants, chitin in fungi). But these are only superficial similarities — the most fundamental difference is nutrition: while most land plants are ‘autotrophs’ that use light to produce carbohydrates via photosynthesis, fungi are ‘heterotrophs’ that eat molecules made by others.
Discover the weirdest fungi in the world, from dead man’s fingers to ‘zombie fungi’
Fungi aren’t producers, they’re consumers – like animals. But whereas animals ingest food before breaking it down inside their bodies, fungi release enzymes to digest food externally then absorb the resulting nutrients into their cells.
Why is fungi important?
The majority of fungi are terrestrial and many are ‘saprotrophs’ that cause decay while feeding on organic matter. As decomposers of dead organisms, they recycle carbon and other molecules, making them essential to ecosystems.
Fungi are also food to humans – edible mushrooms, moulds in blue cheese and yeasts used for fermentation in baking and brewing. They’re important to our health, too: fungi can cause infections such as thrush (yeast) and ringworm (mould) but they’ve also given us medicines like statins and penicillin.
What do fungi look like?
A mature individual might be a single-celled yeast or (like all animals and plants) have a body made of multiple cells. The bulk of a multicellular fungus comes from branching, thread-like hyphae — microscopic filaments that resemble plant roots (but hundreds of times thinner) and create a mass called mycelium. Mycelium can feel wispy, as in moulds, or form more solid structures like the stalk and cap/cup of mushrooms (the word ‘fungus’ stems from Greek for sponge).
- Hair ice fungus: what it is and how this rare magical winter sight forms
- What is a fairy ring and what causes mushrooms to form a circle?
How does fungi reproduce?
Many species produce spores that, like pollen or seeds, are dispersed (usually by wind) before they settle and grow hyphae. Around 98 per cent of known fungi come from two groups, sac fungi (ascomycetes) and club fungi (basidiomycetes): a sac fungus’ spores are enclosed in a bag-shaped structure called an ascus, while a club fungus’ spores are released from club-like stalks – both can be within a ‘fruiting body’ below the surface (in truffles) or above ground (mushrooms).
Some fungi reproduce asexually as clones: a yeast will copy itself by fission (the cell splits in two) or budding, while a mycelium can fragment to establish new colonies. Other fungi may meet and exchange genetic material through sexual reproduction. Note that while fungi have sex, they don’t have sexes — male and female – but ‘mating types’ instead (the split-gill mushroom has over 23,000!)
What about symbiotic relationships?
Lichen are fungi living in close association with algae or bacteria. Another well-known symbiosis occurs when hyphae penetrate a plant root system to form ‘mycorrhizae’ (fungus-roots).
What are mycorrhizae?
This is often a mutually beneficial partnership: the plant gets help absorbing water and minerals, the fungus gets carbohydrates. Mycorrhizae have been found in over 90 per cent of plant families, and they can can connect neighbouring trees to create a common mycorrhizal network or ‘wood-wide web’ that some scientists claim enables different plants to communicate.
But symbioses can be parasitic, too. The world’s largest living organism may be a specimen of Armillaria ostoyae nicknamed the ‘Humongous Fungus’, whose root-like hyphae are twisted into cords (rhizomorphs) that steal nutrients from host plants and covers an area of almost 10km2 in Oregon.
We named another fungus, the zombie Cordyceps, one of the deadliest parasites in the world thanks to its ability to directly breach the exoskeleton of their insect victim. Spores of the fungus attach themselves to the outer body and bore through the skeleton as they germinate. Once within, the mycelium (fungal threads) invades and eventually replaces the body tissues.
How many species of fungi are there?
About 155,000 have been described but the true figure has been estimated at 2-3 million species. To recognise the kingdom’s ecological importance and the fact that biodiversity goes beyond animals and plants, the International Union for Conservation of Nature recently adopted a new phrase: fauna, flora and funga.
Enjoy learning about fungi? Check out our rundown of the very best fungi books, so you can read more about fascinating fungi!