Mycelium / Mycorrhizal Fungi

Dig up a handful of forest soil and you're holding 100 miles of fungal filament. Threads ten times thinner than human hair form mycorrhizal networks - literally 'fungus-root' partnerships - that connect trees across entire forests. The fungus extends a tree's effective root system by 1000x, accessing water and nutrients the tree can't reach. The tree provides sugars from photosynthesis that fungi can't produce.

But mycelium does more than bilateral exchange. A single fungal network can link dozens of trees of different species and ages. Large trees in sunlight send excess sugars to shaded seedlings. When a Douglas fir is attacked by bark beetles, it sends chemical alarm signals through the fungal network - trees 30 feet away begin producing defensive compounds before a single beetle reaches them. Biologists call this the 'wood wide web.'