One of the mysteries of the English language finally explained.
Definition of mycetes in US English:
mycetes
noun
Biologyrare
Treated as plural. Originally: fungi and bacteria (considered as a division of the vegetable kingdom). Now: specifically fungi, especially microscopic pathogenic fungi.
Origin
Late 19th century; earliest use found in Von Ziemssen's Cyclopaedia of Practical Medicine. From post-classical Latin Mycetes (in K. P. J. Sprengel Systema Vegetabilium (ed. 16) IV. 376) from ancient Greek μύκητες, plural of μύκης mushroom, fungus.