Truffles are the fruiting bodies of ectomycorrhizal fungi associated with the roots of certain types of trees.

Unlike other types of mushrooms which grow above ground and produce wind-dispersed spores, truffles fruit below ground. To disperse their spores, truffles have evolved to produce powerful natural aromas when mature. The smell attracts forest animals to find and eat the truffles and the spores are then scattered around the forest when they emerge from the animal’s digestive system.

Although there are many species of truffle only a small number are sought after for culinary use.  The many different species of truffle have broad similarities in the way they grow and collectively share some of the multiple volatile chemical compounds responsible for truffle aroma. However, there are also many significant differences between species. These include ecological range (climate/temperature), fruiting season, size, colour, appearance, aroma, taste, use and commercial value.

“Ectomycorrhizal” refers to the combined host tree root/fungus structure of truffles and some species of mushroom. Ecto means the fungus is mainly around the outside of the tree roots.  Mycorrhizas are the structures which enable the symbiotic (mutually beneficial) relationship between the host tree and the fungus to be formed. The fungus physically extends and enhances the tree root system’s ability to access soil trace elements, in particular phosphorous, and in exchange, the tree supplies the fungus with carbohydrate derived from photosynthesis, enabling truffle fruiting.