Class Pyrenomycetes rukuni ne na fungi wanda ya haɗa da nau'in nau'in nau'in nau'in 'ya'yan itace (ascocarps) waɗanda yawanci ke rufe a cikin wani Layer na kariya da ake kira perithecium. Wadannan fungi suna haifar da spores a cikin buhunan da ake kira asci da ke cikin ascocarps.Wasu daga cikin fungi a cikin wannan ajin sune cututtukan tsire-tsire, suna haifar da cututtuka irin su apple canker, chestnut blight, da Dutch elm disease. Sauran nau'ikan da ke cikin wannan ajin su ne saprobes, ma'ana suna lalata matattun kayan shuka.