Undocumented migrant spores
For millennia, the geographical distribution of fungal species evolved very slowly: despite their infinitesimal weight, spores generally land only a few meters away from their source. International trade is changing all that. Billions of plants of all kinds cross borders annually and the trillions of spores they contain are virtually undetectable. The death cap (Amanita phalloides), indigenous to Europe, followed the importation of Norway spruce to North America. China truffles (Tuber indicum), of poor quality, have been transplanted in Western Europe where some benefit from their apparent similarity with the indigenous black truffle (Tuber melanosporum).
Recently, wild shiitakes may have been spotted in New England. No surprise: native to Southeast Asia, shiitakes (Lentinula edodes) are extensively cultivated on almost all deciduous trees and can stand our freezing conditions. Shiitake culture kits have been among our best sellers for years. It is surprising indeed that this species has not already gained ground in our forests.
We are witnessing a global upheaval that exceeds the fungal kingdom. The shiitake is a delicious and nutritious fungus that contributes usefully to recycling dead wood, but what about exotic pathogens that prey on native flora?