The lingzhi mushroom or reishi mushroom (“soul/spirit mushroom”) is a species complex that encompasses several fungal species of the genus Ganoderma, most commonly the closely related species Ganoderma lucidum, Ganoderma tsugae, and Ganoderma lingzhi. G. lingzhi enjoys special veneration in East Asia, where it has been used as a medicinal mushroom in traditional Chinese medicine for more than 2,000 years, making it one of the oldest mushrooms known to have been used medicinally. Lingzhi is listed in the American Herbal Pharmacopoeia and Therapeutic Compendium.