A bright yellow mushroom from Asia is spreading rapidly through North American forests, outcompeting native fungi and threatening ecosystem balance. The golden oyster mushroom (Pleurotus citrinopileatus), once cultivated for food, has escaped into the wild and now grows in 25 US states and one Canadian province.

Originally brought to the US around 2000 for its high yield and profitability, the fungus produces billions of spores and forms massive yellow clusters on dead trees. Researchers found that forests colonized by golden oysters have about half the fungal biodiversity of unaffected areas, suggesting the invasive species is crowding out native fungi that evolved alongside local trees over millions of years.

Scientists worry about cascading effects on forest ecosystems, as dead wood habitats for small animals and seedlings could change dramatically. Mycologist Aishwarya Veerabahu notes we don't yet understand all implications, including how altered fungal communities might affect wood decay rates and carbon emissions. Conservation efforts now focus on cloning native species to preserve their genetics before they disappear completely.