Picture the scene. It’s Halloween and you’ve gone for an ill-advised stroll through the graveyard on the edge of town.
As the screams of trick-or-treaters fade into the distance, a shroud of dense fog rolls in, blanketing the tombstones. It already feels like an episode of Scooby-Doo, but things are about to get worse.
You stumble and fall, face-planting into the detritus, where you spot a putrid-looking hand sticking out of the ground. Misshapen digits. Long, twisted nails. You try to scream, but the sound is stuck in your throat.
Where is Velma Dinkley when you need her? Then you look again closely and realise it’s not a hand at all. Although dead man’s fingers (Xylaria polymorpha) may look like it belongs on the end of a dead man’s arm, it’s actually a fungus.
A quick fungus primer: Fungi can’t eat food, like animals, and they can’t make food, like plants and algae. Instead, they secrete enzymes that break down nearby organic matter, releasing nutrients that they can then absorb.
Disappointingly, given its zombie-like appearance, this fungus doesn’t break down dead bodies, but dead wood. It can be found, sprouting from the rotting base of broadleaved trees such as beech and oak. Hence the first part of its Latin name, ‘xylaria’ means ‘growing on wood.’
The second part of its Latin name, ‘polymorpha’, means ‘many shapes’, reflecting the fact that this fungus changes in appearance over time. In spring, when it emerges, it sprouts in clusters of three to six ‘fingers’, which are pale to dark grey, each with a pale ‘nail’ at the top.
But by winter, when it’s mature, each finger is up to 10cm (4in) tall and dark brown to blue-black. For this reason, it has been described as looking like a putrid finger, a piece of burned wood, and a mummified penis.Fungi aren’t mobile, so they spread by producing spores that they disperse from their fruiting bodies, which are the bits of the fungus that you can see above the ground. In this case, the fingers are the fruiting body.
Like many fungi, X. polymorpha has two modes of reproduction, asexual and sexual. Asexual reproduction produces genetically identical copies of the fungus. It occurs in spring when the fungus releases spores, called conidia, from all over the surface of the finger.
Meanwhile, sexual spores, called ascospores, are released through a hole at the top. When an ascospore from one parent fuses with an ascospore from another, a new, genetically different fungus is produced.
It may look bizarre and a little grotesque, but this fungus is good news for all the invertebrates that feast on the soft, nutrient-rich detritus it creates.
But don’t be tempted to eat it yourself. A 2018 study found that the macabre-looking fungus contains toxins that are similar to those found in the infamous death-cap mushroom. Tuck in and you could be the one who ends up in the graveyard!
Check out our ultimate fun facts page for more mind-blowing science.
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