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Leopard Earthball - Scleroderma areolatum

Good evening friends,

The rain has been plentiful and so have the mushrooms. I've heard rumblings about whether I will find enough mushrooms in the park to keep this weekly email going and I'm here to assuage you of those concerns. I've seen more mushrooms this past week than I could ever hope to document. We have a great stockpile of summer mushrooms that we will be looking at well into the winter.

This week's mushroom is Scleroderma areolatum, the Leopard Earthball. It gets its common name from its leopard looking skin. This mushroom was found by the cascade in the ramble on 6/30/2021, and it was actually growing during the dry spell before the 7+ inches of rain. It is found across North America and Europe, and it is mycorrhizal which helps explain why it was able to grow in drought-like conditions. Mycorrhizal relationships are fascinating, and not fully understood, but the general idea is that fungi will either wrap their mycelium around the end of plant roots (ectomycorrhizal) or enter the roots to establish a direct transfer of chemicals and nutrients within the plant cell walls (endomycorrhizal). There is a paper documenting S. areolatum as ectomycorrhizal.1 The fungus will provide trees with nutrients like nitrogen, phosphorous, and even water in exchange for the sugars the trees produce through photosynthesis. Plants can have many different fungal partners and the fungi can have many different plant partners - creating a "Wood Wide Web" of connectivity in the forest. This paper also notes that various Scleroderma species are able to grow in less-than-ideal conditions (from coal mining detritus to sand dunes), and their drought tolerance specifically makes them a genus of interest as the planet warms.

The brown you see in the cross-section picture is the spore mass, and the spores are released through a hole in the skin that gets bigger with age. One last interesting tidbit is that this is only the second time the species has been found within the five boroughs, per iNaturalist. As is the case with several of the mushrooms we look at, a microscope would be needed to help confirm the ID, but the other mushroom that shared similar physical features (S. verrucosum) is European.

Have a splendid week and go find a mushroom or two,



1) Mrak, Tanja et al. “Scleroderma areolatum ectomycorrhiza on Fagus sylvatica L.” Mycorrhiza vol. 27,3 (2017): 283-293. doi:10.1007/s00572-016-0748-6


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