Mycorrhiza is the symbiosis between a fungus and a plant. The fungi lives in the root system of the plant. Normally, both the fungus and the plant benefit from the symbiosis.
The fungus helps the plant absorb water and nutrients from the soil.
The plant “in return” helps the fungus get energy from the sun.
A and B show plants with mycorrhiza around their roots, while C and D shows the plant species at the same site, but lacking mycorrhiza. Notice the more green and abundant plant growth of A compared to C. Photo: Klara Hönig & Ingrid Kottke, CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0), via Wikimedia Commons).