De tuberibus haec traduntur peculiariter: Cum fuerint imbres autumnales, ac tonitrua crebra, tune nasci, & maxime e tonitribus. [Pliny the Elder, Hist. Nat., Bk 19:37]
(If the air is troubled and disquieted with many thunders, during that season there will be good store of mushrooms, especially if it thunders much.)
In many European and Asian cultures, there is a snippet of folk wisdom holding that lightning or thunder is good for mushroom fruiting. Gordon Wasson recounts examples of such legends from cultures as distinct as ancient Greece and Rome, France, Germany, Eastern Europe, Iran, Arabia, Kashmir, China, Japan, Madagascar, the Philippines, and Polynesia. In many cases, it is thought that the lightning or thunder itself is the ultimate source of the mushroom. The Arabs even name one species of mushroom banat’ur-ra’d, “The Daughters of Thunder.”
Western scientific mycology has long disregarded this supposed relationship. Either it is superstitious nonsense, in the view of the modern man of science, or else it is mistaking correlation for causation, as the same rainstorm that gives rise to the lightning and thunder also delivers the rains that wake the mycelium from its slumber and provoke its fruiting.
But now, new research from Japan suggests that the unsophisticated folk of antiquity were right to draw this conclusion. By delivering strong electrical current similar to a lightning strike, the investigators were able to induce shiitake mushrooms (Lentinula edodes) to yield approximately twice as much poundage of mushrooms as usual.
The mechanism of action is uncertain, but perhaps the electrical discharge induces a fungal equivalent of the “fight or flight” reaction in response to danger.