Definition
"Fern seed" is a mythical or legendary seed attributed to ferns. Real ferns reproduce via spores, not seeds, so fern seed doesn't exist! In folklore, it was believed to grant invisibility or other magical powers. It was supposedly difficult to find, often associated with midsummer's eve. The idea stems from not understanding fern reproduction. It's more a symbol of mystery than a real botanical entity. It shows how science and folklore can intersect.