RTÉ Food

A mushroom (Old English muscheron, from the Old French mouscheron, French mousseron (same name in English, for a common kind of mushroom), itself perhaps from mousse, meaning moss) is an above-ground fruiting body (that is, a spore-producing structure) of a fungus, having a shaft and a cap; and by extension, the entire fungus producing the fruiting body of such appearance, the former consisting of a network (called the mycelium) of filaments or hyphae. In a much broader sense, mushroom is applied to any visible fungus, or especially the fruiting body of any fungus, with the mycelium usually being hidden under bark, ground, rotted wood, leaves, etc. Mushrooms obtain food through decomposition.