What is a truffle? Truffles are the fruiting bodies (spore-bearing mechanisms) of underground mushrooms. The actual fungus from which the truffles grow are formed by an underground network of mycelium in a symbiotic relationship with a host plant. This mutually beneficial arrangement occurs when the fungal mycelium and the root cells of the plant grow together to create mycorrhizae. The plant provides sugars to the fungus through photosynthesis, and the fungus provides the plant with minerals, water, and other nutrients ...