A beneficial fungus, also known as noble rot, which is necessary to produce many of the world’s great sweet wines, including Sauternes. In certain years, when the degree of humidity is just right, Botrytis cinerea will attack grapes, covering them with a gray mold. The mold lives by penetrating the grapes’ skins and using up the available water in the juice. This concentrates the sugar, flavor, and ACID so that a COMPLEX wine of exceptional sweetness can be made. Botrytis is unique in that, unlike other molds, it produces flavors that harmonize with the flavors of particular grapes.