Hypomyces lactifluorum is exceptional for several reasons: its brilliant hue (see its gill side at the upper right in the photo), its sole common name, and the fact that it is not a mushroom. It is a sandpapery mold-like fungus that covers mushrooms. It grows throughout North America (apparently not in Europe) and parasitizes certain Russula and Lactarius species. David W. Fischer and Alan E. Bessette, authors of Edible Wild Mushrooms of North America, observe that “the mushrooms known to serve as host species are normally unpalatable,” which is “rather odd, when you think about it: something that’s edible only if it does look moldy!” Although old field guides “recommend caution to those who would sample mushrooms parasitized by this colorful and unusual species . . . there is no evidence whatsoever to justify this concern,” stress Fischer and Bessette—as do other experts.