Wood-wide web unravels [excerpt]

"A mat of long, thin filaments that connect an estimated 90 per cent of land plants" (Nakaya 2018)

Welcome to the wood-wide web, a place where trees trade, share and befriend others of their species, and perhaps other kinds, through an underground network of cooperating fungal threads. In some extreme renditions, a benevolent social network where plants support one another through acts of kindness and self-sacrifice. 

A counter view is emerging among those who should know – the mycologists – that while the wood-wide web is a catchy slogan, it is also an overhyped and overextended metaphor, perhaps ‘a fantasy beneath our feet’. 

While nearly all land plants have fungi associated with their roots – called mycorrhizae – there is little evidence yet that these symbiotic associations do more than provide nutrients to a plant in exchange for sugars to the fungus. 

As to this fungal–plant relationship creating an incipient social network of some kind, that is at best wishful thinking. For a start, even though 90 per cent of land plants may have fungi associated with their roots, that does not mean these filaments connect even one plant with another.

In 2023, I attended an online talk by Dr Camille Turong, a research scientist and mycorrhizae expert from Royal Botanic Gardens Victoria, who along with Canadian ecologist, Justine Karst and colleagues, is concerned that the hoopla for the wood-wide web far exceeds the hard science

Drawing on her early life in Switzerland, Turong frames her response around a saying from her childhood, ‘you have put the church back in the middle of the village’, which I take to mean we need to de-escalate the matter, returning it to what we know. Or as I might have put it, quoting Wittgenstein from 1921, ‘whereof we cannot speak, thereof we must be silent’. This is pertinent to what Camille is saying in her lecture. We like to think trees can communicate, she says, particularly with us. 

What we do know is that one plant can associate with more than 30 fungi in mutually beneficial relationships. These mycorrhizae allow plants to live in environments where they otherwise could not or could hardly do so; in arid and nutrient-poor terrain, through drought, and after fires. 

Turong points out that these fungi are obliged to be symbionts, while the plants are not. Plant can live without the fungi but perhaps not so well and not in so many places. Because plants typically produce excess carbon in the form of sugars that fungi need to survive, it is a low cost to the plant. In a high nutrient environment – such as in potting mix – fungal partners are not needed...

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For the rest of this essay, see: Entwisle, Tim (2025) The Sceptical Botanist: Separating Fact from Fiction, p. 213 (CSIRO Publishing). This excerpt is from the Kindle Edition. Illustration: Jerome KS Entwisle

I was driven to post these introductory paragraphs after reading yet another breathless account of the allegedly interconnected underground network of mycorrhizal fungi known as the 'wood-wide web'. Mycorrhizae exist and sometimes, it seems, extend from one tree to another. But how often and to what end? These are the so-far unanswered questions.