Fungi are one of the oldest, if not the oldest, living organisms on earth. The first land plants, green algae, moved out of the water around 600 million years ago. This was beneficial for the photosynthetic organisms, as they gained direct access to sunlight and carbon dioxide. However, the Earth’s surface was harsh, dry, and had no organic soil where plants could root. They likely would never have succeeded in colonizing and evolving if land-dwelling mycelial networks didn’t exist first.

From the very beginning of life on Earth’s surface, plants and fungi have come together in mycorrhizal relationships. Fungi inhabit plants’ root systems, allowing plants to access nutrients gathered by fungi and fungi to glean what they cannot access from plants. Over 90% of modern plants rely on fungi in some way. Mycorrhizal relationships can be very complex, but generally involve plants transferring energy from sunlight and carbon dioxide to fungi, and fungi using hyphae filaments to access nutrients in tiny pockets of rock or other places that plants’ roots cannot reach. Plant-fungal relationships can look very different depending on the plants, the fungi, and the ecosystem in which they evolve. These relationships are just beginning to be understood.