Laser scan of a root. Plant in blue; symbiotic mycorrhizal fungi in red. The sac-like structures form when fungal hyphae swell within plant cells, eventually bursting to release their contents. By partnering, plants gain a prosthetic fungus, and fungi gain a prosthetic plant. Both use the other to extend their reach.

This scan depicts a root of Voyria tenella, a small gentian flower that has lost the ability to photosynthesise. These plants are neither green, nor do they have leaves. They grow in deeply shaded parts of the forest understory where few other plants can live. But how?

Voyria, like most land plants, depend on mycorrhizal fungi. But their symbiotic manners differ. Photosynthetic plants receive mineral nutrients from their fungal partners and in return supply the fungi with energy rich carbon compounds. Voyria have evolved a way to bypass this exchange. Instead, their roots have evolved into fungal farms, allowing them to draw both carbon and mineral nutrients from their fungal associates and don’t seem to give anything back.

Then where does Voyria’s carbon come from? Voyria’s mycorrhizal fungal partners obtain all of their carbon from photosynthetic plants. This means that the carbon that powers the life of Voyria — and which makes up the stuff from which they are made — must come from nearby photosynthetic plants through a shared fungal network. If carbon couldn’t pass from plant to plant through mycorrhizal fungi, Voyria could not exist.

Video © Merlin Sheldrake