Photo shows P. domesticum mycelium and fruitbodies on experimentally burnt soil (A), with a blowup of the fruiting bodies (B), and a 400X view of the asci and paraphyses (C). Photo credit: Tom Bruns.

Pyronema domesticum (Sowerby) Sacc. is a tiny pink to orangish cup fungus from the family Pyronemataceae that occurs on burnt or sterilized soil, and typically fruits within a few weeks after a burn.  It is occasionally found in buildings and on sterilized materials.  It grows very rapidly in culture, where it is known to form sclerotia.  These sclerotia along with the less fused fruiting bodies distinguish it from P. omphalodes, a close relative that is more restricted to fire settings. Its rapid growth after fire is of interest because post-fire soils are rich in hydrophobic compounds and partially burned substrates that can last in the environment for decades and affect site productivity.  This and other pyrophilous fungi are likely to affect the fate of these compounds in the soil.