Putrid

Why would mushrooms smell of rot?

M.Ya. Zerova in the "Key to the Fungi of Ukraine" explains that a putrid smell is a hallmark of the stinkhorn family (Phallaceae). These fungi have given up the traditional way of spreading spores by wind. Instead, they have "bet" on insects.

David Arora in "Mushrooms Demystified" describes the mechanism: the spores of these fungi sit in a thick, sticky, greenish slime (the gleba) that coats the tip of the mushroom. To attract flies and carrion beetles that feed on dead animals, the fungus synthesizes compounds that mimic the smell of rotting meat or rotten eggs (hydrogen sulfide and amines). The flies swarm to the smell, crawl over the slime, get it stuck to their legs, and then carry the spores all over the forest.

Roger Phillips in his guide "Mushrooms" describes the best-known species with a putrid smell:

1. Common stinkhorn (Phallus impudicus): A very phallic-looking mushroom. At the white "egg" stage it has no smell (and is even edible raw), but when the receptacle shoots up, the slime starts giving off an unbearable stench of a dead body that you can smell 10-15 meters away.

2. Devil's fingers (Clathrus archeri): A fungus brought to Europe from Australia that looks like red octopus tentacles hatching from an egg. Its smell is also repulsively putrid.

3. Dog stinkhorn (Mutinus caninus): A smaller, slimmer relative of the Common stinkhorn with an orange tip, which smells a little weaker but just as unpleasant.

Besides the stinkhorns, old, overripe specimens of absolutely any edible mushroom can have a putrid smell (for example, old porcini infested with larvae), where bacterial breakdown of protein has already begun.