The ascomata are simple and contain only a single perithecium. The asci are cylindrical and arranged inside the flask-shaped perithecium. The mature perithecium has a flask-shaped structure. The most common types of ascomata are the "apothecium" (plural&colon; apothecia) and "perithecium" (plural&colon; perithecia). The asci are protected by a perithecium, a flask-shaped ascocarp, in which the pathogen overwinters. The microscopic signs of the perithecium are the flask-shaped sexual fruiting body that contains ascospores. When each ascus becomes engorged with fluid it extends outside the perithecium and releases spores.