Abstract
Fifty-two isolates of Penicillium viridicatum Westling were divided into three groups based on ability to produce ochratoxin and/or citrinin, color, growth rate, type of growth, odor, and isolation source. Members of group I resemble one of the representative strains of P. viridicatum described in the literature; those belonging to group II differ from group I strains in several characteristics; group III is a heterogeneous series of highly variable isolates. Although three subgroupings can be recognized, retention of all isolates in the species P. viridicatum is deemed most appropriate at this time. Spore macerates of all isolates were examined for virus-like particles but none were detected.