Mycelium

Under almost every plant on land runs a web of fungal threads, trading water and minerals for the sugar the plant makes. These are the best maps yet of where that web is thickest.

• AM hyphaeArbuscular mycorrhizal fungi grow inside the roots of most plants, from grasses and crops to tropical trees. Shown as metres of hypha in each cubic centimetre of topsoil.
• EcM rootsEctomycorrhizal fungi sheathe the roots of pines, oaks, birches and beeches, the trees of the northern forests. Shown as tonnes of root carbon they colonise per hectare.

What you’re looking at

Both maps are models: thousands of soil samples, matched to climate, soil and plants, then predicted for everywhere else. They’re averaged here into half-degree squares, about 55 km across. The threads are drawn thicker where more is predicted; each one is a picture, not a measured hypha. Today’s soils only.

Psilocybin mushrooms mostly aren’t part of this web: they feed on dung, wood and rotting leaves rather than partnering with roots. For where they grow wild, see Where they grow.