Objective The process of flower blooming is accompanied by the coordinated movement of various flower organs, especially petals, however, the mechanism of petal movement and flower blooming is still unclear. In this study, the physical process of flower blooming and epidermal cell anatomy of two different flowers of the same family, “lily” and “Leek”, were observed to understand the similarities and differences of blooming mechanism and anatomical structure of lily and leek petals.

Method Using Oriental lily “Sibirica” and Isoetes “Rose-red” as experimental materials, the factors promoting the blooming of Oriental lily and isoetes were studied by measuring the length of petals, counting the number of cells and observing the morphological changes of cells in different blooming periods by anatomical and physiological methods.

Result The blooming process of lily flowers can be divided into five stages: S1−S5 stage. The length of petals gradually increased and the cell morphology changed obviously in S1−S5 stage. The number of cells increased significantly in S1−S2 stage and the number of inner epidermal cells increased significantly than that in outer epidermis, but the number of cells in S2−S5 stage didn’t increase significantly. The flower blooming process was divided into three processes: T1−T3. There were no significant changes in petal length and cell morphology in T1−T3. The number of inner epidermal cells was greater than that of outer epidermal cells in T1 and T3, but the opposite was true in T2.

Conclusion There were obvious differences in the number of epidermal cells inside and outside the lily in S2 stage, which promoted the sudden blooming of lily petals. The difference in number of epidermal cells inside and outside the lily in S3, S4 and S5 stages was small, which may be due to the expansion and growth of cells leading to further blooming of petals until the flowers withered and faded. The number of epidermal cells in the T2 stage was significantly greater than that in the inner epidermis, and the number of epidermal cells in the T3 stage was significantly greater than that in the T3 stage. It is speculated that the asymmetric growth of the number of cells on both sides of petals is the reason for the opening and closing of the flowers in T2 stage.