No, truffles don't grow on trees, but the trees are crucial in making good truffles:
Truffles multiply by spores and observation of these under a microscope is the only absolutely certain way to distinguish one species from another. The black truffle or rabasse grows in a strange symbiotic relationship with the roots of several trees but oaks are the most productive, particularly the evergreen Holm Oak (Quercus ilex) and the deciduous White Oak (Quercus pubescens).
The truffle enables the tree to assimilate phosphorus and in return it receives sugars to enable it to grow. It does this by producing mycorrhiza (tiny 2 to 3mm swellings the colour and shape of a miniature date) which invade the tree roots. The truffle develops over many months and harvesting can begin as early as 15th November although tradition has it that the best truffles are to be found between mid January and mid February.
Oh, and my tree? Is in Gascony.
I think I need to visit it in person, soon, and whisper encouragement to it, to help it make good truffles for Papa. And then adjourn to a nearby village for foie gras, charcuterie and vin.
Thanks, dear Carrie. You made my 30s the nicest decade of my life; I'm looking forward to experiencing advancing geezerhood with you.
Truffle Tree: Buy a piece of tranquility
Related: La gastronomie de la truffe / All about truffles