 Due to the seemingly transitional nature of the hysterothecium, neither fully open nor closed, hysteriaceous fungi have been placed in the discomycetes and pyrenomycetes about equally by various mycologists throughout the 19th Century.In his "Systema Mycologicum", Fries (1823) initially considered hysteriaceous fungi to belong to the pyrenomycetes and placed them in the order "Phacidiacei", but later (1835) placed them in his new class discomycetes, stating