The most important roles

Scientists believe this mutualistic relationship was essential to the evolution of land plants – a hypothesis strengthened 15 years ago with the discovery of 460-million-year-old fossil mycorrhizae that date from before the evolution of land plants.

    Water storage and filtration is one of the most important roles soil plays

“This mutually beneficial relationship helped plants to colonise the land before they had roots and before there was soil as we know it today,” explains Katie Field from the University of Leeds, UK. “As time progressed, plants evolved to become more structurally complex, developing extensive vasculature, leaves and rooting systems”, she says. This brought more organic matter into the soil and helped stabilise it against erosion.

Today, mutualistic relationships like these form the basis of global nutrient cycling, without which we would starve. More than 80% of modern plants form mycorrhizal relationships with filamentous fungi, and they are crucial for releasing nitrogen into the soil.

Mycorrhizae also form huge networks, which stabilise the structure of the soil and enable plants to communicate, gaining them the nickname “Earth’s internet”.