Abstract: Stomata density,stomata index,and guard cell size on normal and abnormal Bougainvillea spectabilis Willd leaves were investigated.Results showed that epidermal cells were polygonal with straight anticlinal walls in the adaxial epidermis of the normal leaf;while in the abaxial epidermis,the epidermal cells were irregular with repand an-ticlinal walls.Normal leaf stomata were anomocytic.No stomata were found in the adaxial epidermis of abnormal leaf,while epidermal cells were repand or sinuous.Stomata were anomocytic and cyclocytic.With abnormal leaf development,stomata density on the abaxial epidermis decreased and stomata index increased;guard cells lengths on the abaxial epidermis increased and widths decreased.Average stomata density and average stomata index on abnormal leaves were significantly lower than on normal leaves.Guard cells were kidney-shaped on both normal and abnormal leaves.