Abstract: To investigate the flowering phenological rhythm and floral morphological variation characteristics of Acacia mangium in Southern Fujian,a field observation was conducted in 2024 using a 6-year-old experimental plantation of A.mangium at Zhangpu Zhongxi State-owned Forest Farm in Fujian Province.The results revealed that the stand flowering period of A.mangium stands in Southern Fujian generally extended from early September to early November,with the complete phenophase,from flower bud sprouting to the late flowering stage,lasting approximately 73 days.Specifically,the budding stage lasted 28 days,the initial flowering stage 18 days,the full flowering stage 9 days,and the late flowering stage 18 days.A single floret peak occurred during the initial flowering stage,with a duration of approximately 4 days.Flowering cycles varied among individual plants,which were classified into unimodal,bimodal and non-flowering types based on the dynamic changes in flowering proportion.The inflorescences were spicate,and their growth and development categorized into six stages: flower bud differentiation,initial bud,bud swelling,anther development,anthesis(flowering)and withering.During the full flowering stage,inflorescence length was(6.79±1.16)cm,and the number of florets per inflorescence was(122.75±23.85).Each floret contained zero or one pistil,with an average stamens number of(58.50±9.14).This study provides a theoretical basis for understanding the flowering phenology of A.mangium in Southern Fujian,and offers a reference for the crossbreeding of this species.