Abstract: Lonicera confusa is the main source plant producing lonicerae flos in South China. In the present study，transmission electron microscope（TEM），histochemical methods and fluorescence microscope were employed to investigate the ultrastructure and accumulation law of chlorogenic acid in Lonicera confusa flower at different developmental stages. The results showed that，with the development of the flower，the structure of chloroplast in corolla tube gradually became perfect，and the starch grains began to accumulate in the chloroplast. The grana and grana lamella appeared in the chloroplast with no starch grain at the stage of young alabastrum. The chloroplast with perfect structure at the stage of green alabastrum accumulated one or numbers of starch grains. A small amount of chloroplasts containing abundant starch grains existed at the stage of white alabastrum. At the stages of silvery and golden flower，there was nearly no chloroplast in corolla tube. Lignification gradually thickened in the cell wall of vessels in the xylem of corolla tube.Abundant chlorogenic acid accumulated in the corolla tube at the stages of young and green alabastrum. The chlorogenic acid content in parenchyma cells at the stage of white alabastrum began to decrease，with relatively high level of chlorogenic acid accumulation in vascular bundle. The chlorogenic acid content in parenchyma cells at the stages of silvery and golden flower further decreased，with scattered distribution. The chlorogenic acid accumulation level in vascular bundle began to decrease，with the main distribution of chlorogenic acid in the xylem ray. Additionally，the chlorogenic acid was examined to be distributed in parenchyma cells，vascular bundle，axial placentation，and ovule in the calyx tube-ovary of the flower at different developmental stages. The present study demonstrates that chlorogenic acid is biosynthesized in the chloroplast，transferred to cytoplasm，and finally accumulated in the vacuole. The number of starch grains in the chloroplast is negatively related with the biosynthesis of chlorogenic acid.

Key words: Lonicera confusa DC., developmental stage, flower ultrastructure, chlorogenic acid, accumulation law