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The fungus in the photo (below) appeared on rotting, chopped-up trees used as mulch in our garden. It is about 10 centimetres in diameter and appears to feed on insects, and so has an appropriate stink of rotting flesh. What is it?
鈥� The fungus is Aseroe rubra, literally 鈥渄isgusting red鈥�, whose common names include sea anemone, starfish and stinkhorn fungus. Found in Tasmania and as far north as south-east Queensland, it has the distinction of being the first fungus from Australia to be scientifically described. It was named, no doubt after he smelled it, by botanist at , Tasmania, in 1792.
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The fungus appears to do a good job of mimicking a wound on an animal 鈥� an interesting piece of evolution, if true. It looks a bit like a fly trap, but it doesn鈥檛 catch or eat flies. Instead, it uses them to spread its spores. For food it uses wood in the mulch or forest litter that it inhabits.
The fruiting body in the photo shows the smelly black spore slime that acts as a fly attractant. I find its odour more like that of rotting teeth than rotting flesh, a concentrated essence de caries.
The fruiting body only lasts a few days but rewards quiet observation. Our Aseroe specimens attract the rather beautiful, though agriculturally troublesome, green blowfly.
Kevin Maher, Witta, Queensland, Australia
鈥� Curiously, this fungus has leapt several continents and established itself in the UK on in Surrey, where it has been appearing exotically for the last 10 years or more.
The fungal fruiting body doesn鈥檛 catch flies any more than a ripe apple catches wasps. The flies (which tend to be mainly bluebottles in the UK) are attracted to the carrion smell of the slimy spore mass supported on the tentacle-like arms. The slime contains sugars and the flies ingest it, spores and all. These pass through the gut unharmed and are dispersed elsewhere. The fungus itself 鈥� visible as a white mycelium 鈥� lives on rotten, often buried, wood.
A related Australian species with longer tentacles, Clathrus archeri or the devil鈥檚 fingers, has also become established in southern England and is now quite widespread, as is the European Clathrus ruber, or cage fungus, whose tentacles mesh to form a cage-like receptacle.
More common and more familiar is our native stinkhorn, which also lures flies to help spread its spores. The stinkhorn forms fruiting bodies as obvious as the plant鈥檚 Latin name, Phallus impudicus, suggests. It is said that Charles Darwin鈥檚 daughter Etty used to rise early to destroy any that she found, in order to ensure that the morals of her maids were not corrupted.
Peter Roberts, Royal Botanic Gardens, Kew, Surrey, UK