White winter truffles are only found in the wild and elude cultivation. They are the most rare, aromatic, and flavorful truffle species. Their habitat is limited to parts of Italy and Croatia where they grow in forests. Specially trained dogs are used to sniff-out truffles up to a foot under ground. Once located the dog is rewarded with a treat and the hunter digs delicately with small shovels designed for this task. All truffles form symbiotic relationships with the trees around them. Their mycelium help the tree absorb more nutrients from the soil and in exchange the tree provides sugars made through photosynthesis. White truffles are evolutionary precursors to black truffles which have adapted a skin or gleba, which protect the truffle from moisture loss and insects. The protective gleba has allowed black truffles to grow in many more climates beyond the range of white truffles.