Unlike saprotrophic mushrooms, mycorrhizal mushrooms grow by weaving themselves into the roots of trees and other types of plants. This gives moisture and nutrients to the plants, while the mushrooms eat the sugars produced by the vegetation. Porcini mushrooms are likely the most commonly eaten mycorrhizal fungi. Some varieties never come above ground, making these fungi harder to find and observe.
For example, one of the most expensive mushrooms in the world – the White Truffle – is a type of mycorrhizal mushroom. These mushrooms grow symbiotically with oak, poplar, hazel, and beech trees. Essentially, mycorrhizal mushrooms break down nutrients for the tree and the roots of the tree provide the mushroom with sugar in a mutually beneficial relationship.
The prized “white truffle” is simply the underground reproductive body created by the network of fungi surrounding the roots of these trees. Because they are hard to see, many truffle hunters train pigs to find the mushrooms by scent to help locate and unearth these tasty fungi!