The finest black truffles come from France, particularly the southwestern region known as the Dordogne. Historically as well as currently, the most famous black truffle of all is from a specific part of the Dordogne called the Périgord. In fact, fresh French winter black truffles are often called the “Diamonds of Périgord.” They are simply exquisite, and from December to March, French truffle markets feature delectable Périgord black truffles characterized by a subtle aroma and an earthy flavor reminiscent of a rich chocolate. They reach their pinnacle of fragrance and flavor in January and February.
Like other varieties of truffles, the Périgord black truffle (Tuber melanosporum) grows beneath the surface of the soil among the root systems of specific types of trees and develops a symbiotic relationship with those trees, which primarily consist of oak, but also beech, hazelnut, chestnut, birch and poplar. With the exception of the white Alba truffle, Périgord truffles are scarcer, more desirable and higher-priced than other truffles. Within the last 100 years production of these almost incomparable delicacies has significantly diminished from previous levels, but demand among discerning epicures remains justifiably strong.
Reference: enjoyfoiegras.com