This document describes the biology of Carica papaya L. with particular reference to the Australian environment, cultivation and use. Information included relates to the taxonomy and origins of cultivated C. papaya, general descriptions of its morphology, reproductive biology, biochemistry, and biotic and abiotic interactions. This document also addresses the potential for gene transfer to occur to closely related species. The purpose of this document is to provide baseline information about the parent organisms in risk assessments of genetically modified C. papaya that may be released into the Australian environment.