Orculiform, [see polarilocular].

Orthidium, supposed new type of fructification in lichens, [192].

Palisade-cells, the terminal cells of the hyphae forming the fastigiate cortex, [82], [83].

Panniform, having a felted or matted appearance, [260].

Paraphysis, sterile filament in the hymenium, [157].

Parasymbiosis, associated harmless but not mutually useful growth of two organisms, [263].

Parathecium, hyphal layer round the apothecium, [157].

Peltate, term applied to orbicular and horizontal apothecia in the form of a shield, [336].

Perithecium, roundish fructification usually with an apical opening (ostiole) containing ascospores, [158] et passim.

Pervious, referring to scyphi with an opening at the base (Perviae), [118].