Talk about Deuteromycetes.

Imperfect fungi sexual reproduction (perfect stage) serve as a basis for fungal taxonomy is unknown and has not been observed in this group, so they are unclassifiable and a second (deutron-) class or as imperfect form comparing with sexually active ones. Saprophytic, some are human pathogens. Great economical purposes Penicullium synthesizes antibiotics penicillin to treat bacterial infection. Also used in cheese manufacturing.