A Short History of Nearly Everything

by Bill Bryson

Fungi, the group that includes mushrooms, moulds, mildews, yeasts and puffballs, were nearly always treated as botanical objects, though in fact almost nothing about them—how they reproduce and respire, how they build themselves—matches anything in the plant world. Structurally, they have more in common with animals in that they build their cells from chitin, a material that gives them their distinctive texture. The same substance is used to make the shells of insects and the claws of mammals, though it isn’t nearly so tasty in a stag beetle as in a Portobello mushroom. Above all, unlike all plants, fungi don’t photosynthesize, so they have no chlorophyll and thus are not green. Instead they grow directly on their food source, which can be almost anything. Fungi will eat the sulphur off a concrete wall or the decaying matter between your toes—two things no plant will do. Almost the only plant-like quality they have is that they root.