Microsporogenesis and flower development in Eucalyptus urophylla 9 E. grandis were examined using chromosome tableting to provide a method to predict the meiotic stages in this species. Although microsporogenesis was normal, cytokinesis during meiosis of pollen mother cells occurred simultaneously, with strong asynchronism observed in the two different lengths of stamens in a flower bud. In a single flower, the developmental period of microsporogenesis in anthers on the longer stamens was always ahead of those on the shorter stamens. Flower development was also asynchronous at different locations on a branch. Flower buds on the upper side of the branch were larger in diameter than those on the lower side. In addition,a correlation was observed between microsporogenesisdevelopment and flower bud diameter growth. The pachytene stage was first observed when the diameter of the flower buds increased to 3.0 mm, and the majority of the meiotic stages were observed when bud diameters ranged from 3.5 to5.0 mm. This study showed that the developmental stages of microsporogenesis in Eucalyptus urophylla 9 E. grandis could be distinguished readily, which may be applicable to future breeding studies. Microsporogenesis and flower development in Eucalyptus urophylla 9 E. grandis were examined using chromosome tableting to provide a method to predict the meiotic stages in this species. Although microsporogenesis was normal, cytokinesis during meiosis of pollen mother cells occurred simultaneously, with strong asynchronism observed in the In a single flower, the developmental period of microsporogenesis in anthers on the longer stamens was always ahead of those on the shorter stamens. Flower development was also asynchronous at different locations on a branch. on the upper side of the branch were larger in diameter than those on the lower side. In addition, a correlation was observed between microsporogenesis development and flower bud diameter growth. The pachytene stage was first observed when the diameter of the flower buds increased to 3.0 mm , and the majority of the meiotic stages were observed when bud lesions ranged f rom 3.5 to 5.0 mm. This study showed that the developmental stages of microsporogenesis in Eucalyptus urophylla 9 E. grandis could be distinguished readily, which may be applicable to future breeding studies.