This research clarifies which species of the medicinal mushroom genus Ganoderma are actually present in the United States. For many years, multiple different species were incorrectly labeled as a single European species (G. lucidum). Through detailed analysis of DNA and physical characteristics, the researchers identified 12 distinct native species in the U.S., with the European species only found in two small introduced populations. This has important implications for: • Accurate identification of medicinally valuable Ganoderma species in North America • Understanding which species cause decay in different types of trees • Preventing the spread of non-native fungal species through mushroom cultivation • Proper labeling of Ganoderma products in the medicinal mushroom industry • Conservation of native North American Ganoderma species