fungus root - what is that?

Fungus root

The fungi's hyphae and tree roots may grow into each other. The hyphae envelop the roots
and can even penetrate them. It looks like the roots have thickened in places. This is called "fungus root" or mykorrhiza.

Interaction

The root can quickly regain nutrients, liberated when the fungus decompose dead organisms. In return, the fungus absorbs energy-rich substances from the roots produced by the plant.