Trichoderma asperellum Samuels, Lieckf & Nirenberg is a species of fungus in the family Hypocreaceae. It can be distinguished from T. viride by molecular and phenotypic characteristics. The most important molecular characteristics are divergent ITS-1 and 28S sequences and RFLP's of the endochitinase gene. Main phenotypic characters are conidial ornamentation and arrangement and branching of the conidiophores.