Abstract: Abstract: 【Objective】This study aimed to evaluate the morphological differences in Phyllostachys glauca leaves, analyze changes in the ultrastructure and photosynthetic responses of the spathes during flowering, explain the mechanisms of bamboo leaf senescence, and explore the reasons for bamboo plant death after flowering. 【Method】Normal leaves of non-flowering and flowering bamboo plants and spathes at different flowering periods were collected and fixed in volume fraction 70% FAA in order to observe their microstructure. Some leaves were fixed in glutaraldehyde in order to observe the ultrastructure. The leaves of bamboo plants that were growing well, without damage from pests or disease, were selected for determination of the photosynthetic rate. 【Result】During the flowering period, the distance between the adjacent vascular bundle and transverse area of the spathe vascular bundle decreased with continuous development of flowers. The spathe chloroplasts showed obvious starch grains, thylakoids, matrix lamellae and osmiophilic granules. The chloroplast structure collapsed in the later flowering period. The maximum photosynthetic rate of three different functional leaves decreased by 87.03%, 62.48% and 55.00%, respectively, in the late flowering period of Phyllostachys glauca. 【Conclusion】During the Phyllostachys glauca flowering period, the area and quantity of the leaf vascular bundles continuously decreased, therefore diminishing the ability of leaves to synthesize and transport nutrients. The leaves then gradually became senescent, which may be the major reason for death of bamboo plants.