In Ascomycetes, the mycelium is branched and septate. Yeast are an exception in that they are basically unicellular. In majority of Ascomycetes, the common mode of asexual reproduction is through the formation of conidia. Conidia are produced exogenously from the tips and sides of hyphae called conidiophores. Sexual spores are called ascospores which are produced endogenously in a sac like asci (sing. ascus). Ascospores are produced internally in each ascus. The asci may occur freely or get aggregated with dikaryotic mycelium to form fructification called ascocarps