Ascus

Plural �Asci, � a saclike structure produced by fungi of the class Ascomycetes (sac fungi) in which sexually produced spores (ascospores), usually four or eight in number, are formed. Asci may arise from the fungal mycelium (the filaments, or hyphae, constituting the organism) without a distinct fruiting structure, as in the leaf curl fungi; it may arise within a fruiting structure (ascocarp)