Flowering time in a base population trial of Eucalyptus globulus ssp. globulus was highly variable and under strong genetic control. Races from the east coast of Tasmania and the Furneaux Group flowered approximately 1 month earlier than races from Victoria and King Island. These racial differences in flowering time were inherited in an additive manner in interprovenance F, hybrids, whereas the flowering time of interspecific F, hybrids between E. nitens and E. globullus was more similar to the late-flowering E. nitens.