cleistothecium

noun

cleis·​to·​the·​ci·​um ˌklīs-tə-ˈthē-sē-əm 

plural cleistothecia -sē-ə 

: a closed spore-bearing structure in some ascomycetous fungi from which the asci and spores are released only by decay or disintegration

cleistothecial

-sē-əl 

adjective