Their classification rested on three primary "Pillars of Taxonomy":
Often called "Fungi Imperfecti," this is not a natural phylogenetic group but a "holding place" for fungi where the sexual stage has either been lost or not yet observed.
While modern molecular phylogenetics has drastically reshaped fungal taxonomy, the Alexopoulos and Mims system remains a critical historical and pedagogical milestone. It was one of the first systems to integrate cytological features—such as the nature of the flagella and the structure of the cell wall—into a cohesive evolutionary narrative.
