Common Earthball Fungus

2023 February 12

While Sam and I were walking around Lake Perrault on August 27, 2022, we spotted what looked like fairly large puffballs. They had the same shape as puffballs, approximately spherical and without a distinct stem. And the one we picked was quite firm, indicating that it hadn’t fully ripened and turned into a bag of spores yet.

The surface was rougher than what we normally see on puffballs, though. And when we broke it in half, instead of being creamy white inside like an unripe puffball would be, it was as black as tar.

It even looked a lot like tar close up, although it was only moist, not sticky.

This appears to be a Common Earthball fungus, Scleroderma_citrinum. And, as it turns out, they are not puffballs. Which is important to know, because the puffballs that they most resemble (genus Apioperdon) are edible, while the Earthball fungi are not. It sounds like they won’t kill you, but they will cause “gastrointestinal distress”, which usually means severe stomach/intestinal pain, and vomiting/diarrhea. The black interior is a giveaway that this is not an edible puffball. People occasionally mistake Earthballs for truffles, too. They are not truffles.

What we see in these pictures is of course just the fruiting body. The actual fungus is threadlike mycelia that run through the soil and decaying wood, like most other soil/wood fungi. Some of the fungi in this genus will actually set up a symbiotic relationship with trees, where the fungal mycelia will supplement the fine hairs on the plant roots for extracting water and minerals from the soil, while the fungus receives nutrients from the tree roots.

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