In botanical terminology their designation is Tuber melanosporum and Tuber magnatum. Among laymen it’s enough to call them black Périgord or white Alba truffles. Both types are of course not only found growing in these two regions but also in Umbria, Tuscany and the Le Marche region. The high season for truffles is winter – for the white variety from October until Christmas, with the black truffle maturing between January and late March. The inferior “summer truffle” (Tuber aestivum) is the most common variety in Europe – it can even be found in southern Germany and Britain. But in France it is considered nothing more than a commonplace mushroom – and is not permitted to be sold as a truffle. The name originated in the 13th century, when the delicacy was described as “terrae tuffolae” – hump of earth – because the way it grows underground sometimes forces up the soil.

There are more than thirty varieties in Europe, but only ten or so are commercially available. White truffles are better eaten raw, shaved in wafer-thin slices over warm dishes which intensify their aroma – like scrambled eggs, risotto, fresh pasta or toasted bread. Black truffles are usually cooked, mostly to enhance sauces, meat dishes or pies.

Truffles grow 5 to 30 centimetres beneath the ground’s surface, requiring the kind of limey soil that occurs in the Périgord or Piedmont and, like good wines, a Mediterranean climate – no hard winter frost, no biting cold, warm to hot summers, plenty of summer rain and storms in July and August. It takes eight to ten years before the fungus begins to mature in close symbiosis with the roots. “Mycorrhiza” is the term given to this concubinage, which as in real life, is of benefit to both parties. The fungus feeds off the roots of a tree while facilitating the tree’s absorption of hydrogen, nitrogen and phosphates. For their part, the roots supply the thirsty truffle with up to twenty times its own weight in fluid per day.