That’s a great question – and the answer is we don’t really know the true diversity of fungi. It’s estimated that there’s somewhere between 1.5 and 5 million different species, but we’ve only classified around 5% of those. One of the problems is the number of different forms fungi can take – just think about comparing the yeast that you’d use to make bread, with the many types of mushrooms you can find in the supermarket!
Like Bethany I am not sure how many types of fungi are out there. A big difficulty is being able to take samples from the wild to grow in the labs. A lot of the time we just cannot get these fungi to grow and so we cannot study them and learn more about how many types there are.