Fungus is not a load of horse dung

It sure looks like horse dung – and your smart phone is telling you it is indeed the Horse Dung Fungus. Pisolithus arhizus But before you hit submit . . . the computer is not always right.

Expert fungus identifier extraordinaire Garath Jacobs (aka ghjake) recently tuned in on this observation – he noted that Pisolithus arhizus does not occur in Australia. But it is common in the northern hemisphere. Which explains in part why iNaturalist’s computerised vision tools are incorrectly identifying this species – or group of species.

And at least some Australian field guides and collections have also not caught up with the fact that the Horse Dung Fungus is unlikely to occur in Australia.

DNA analysis in 2002 showed at least 5 native Australian species looked like horse dung. These are mostly identifiable only by examining spores under the microscope, but some characteristics of the stalk are also relevant..

At this stage the best that you can do from a photograph is a Pisolithus species unknown – but who knows, computer vision may develop to the point of being able to distinguish species in the future. And DNA analysis will likely become cheaper, allowing regional studies to pinpoint the likely species.

Meanwhile all we can say is that there is a lot more to learn, and always best to be accurate, not necessarily precise.

So for now if you see something that looks like horse dung lying on the road – it is either actual dung from a horse, or a Pisolithus, species unknown, formerly known as the Horse Dung Fungus.

Read more:

Pisolithus in the Budawang Coast – species unknown but definitely not the Horse Dung Fungus in spite of its appearance
These fungi crop up in the most unlikely places, often in the middle of the road. They are mycorrhizal , which means they help plants to take up nutrient – just like real horse dung does!