The Science
The wood wide web, and the evidence that never caught up
Trees feeding their offspring through fungal networks is one of the best-loved ideas in popular science. Three ecologists checked the three central claims. One of them has no published evidence at all.
You will have heard the story. Beneath a forest floor runs a vast fungal network, trees trading sugar and warnings through it, mother trees recognising their own seedlings and feeding them. It is one of the most beloved ideas in popular science, and it has been in bestselling books, documentaries and at least one blockbuster film.
In 2023 three ecologists went through the evidence for it in Nature Ecology and Evolution. Their conclusion was blunt, and it is not what most people have been told.
The three claims
The paper takes the three assertions that appear most often in popular coverage and asks what published field evidence actually supports them.
That fungal networks connecting trees are widespread in forests. Insufficiently supported. Field results vary too widely to generalise from.
That resources travel through those networks to improve how seedlings grow. Insufficiently supported. The studies are too few and too varied, and where effects appear there are alternative explanations that have not been ruled out.
That mature trees preferentially send resources and defence signals to their own offspring. This is the one that made the story famous, and the finding is stark. There is no peer-reviewed published evidence for it at all.
How a story outran its evidence
The authors then did something unusual. Rather than only assessing the claims, they examined how the underlying research gets cited, and found that unsupported claims about these networks have doubled in the scientific literature over 25 years.
That is the mechanism worth understanding. A tentative early finding gets cited slightly more confidently than it deserves. The next paper cites the citation. Popular writers pick up the confident version, because it is a better story. Eventually the claim is everywhere and the evidence never moved.
Their conclusion is that current knowledge is too sparse and unsettled to guide forest management, which is a serious statement given that the idea is invoked in arguments about how forests should be logged and conserved.
What this does not mean
It does not mean mycorrhizal fungi are unimportant. The relationship between fungi and plant roots is real, ancient and central to how terrestrial life works. Fungi genuinely do exchange nutrients with plants, and that is not in dispute.
What is disputed is the specific, romantic version: a connected, communicating, family-aware forest internet. That story ran far ahead of what anyone had shown.
Why we are posting this
The wood wide web is the kind of idea this brand would love to be true. It is beautiful, it points the way we already point, and it would look wonderful on a shirt.
But a brand that only repeats the findings it likes is not being honest, it is being decorative. If we expect you to believe us when we say a psilocybin trial found something real, we have to be the same people who tell you when a favourite story does not hold up.
The fungi are extraordinary enough without it.
Karst J, Jones MD, Hoeksema JD. Positive citation bias and overinterpreted results lead to misinformation on common mycorrhizal networks in forests. Nature Ecology and Evolution, 2023. DOI: 10.1038/s41559-023-01986-1
