Abstract: Flowers can undergo non-foliar photosynthesis, which is mainly affected by stomatal density. However, quantitative information on changes in stomatal density during flower development is still lacking. In the present study, Erythrina corallodendron flowers were classified into 6 developmental stages. The epidermal morphology, epidermal cell density, stomatal density, guard cell length and width of flowers were investigated at each stage by light microscopy. Photosynthesis of flower organs was also measured. Stomata were on the surface of sepal, vexilla, keel, anther, gynophore, ovary, and style but not wing or filaments. Flower organs showed anomocytic, paracytic, and actinocytic stomatal complexes. However, ontogenetic changes in stomatal complexes varied considerably among flower organs. Epidermal cell density on the surface of sepal, vexilla, keel, wing and filaments decreased with flower development, which suggests that the growth of sepal, vexilla, keel, wing and filaments were mainly due to cell expansion. Stomatal density of most flower organs, such as sepal, vexilla, keel, gynophore, and ovary, did not change markedly at later developmental stages. Changes in guard cell length and width varied considerably among different organs during flower development. Unlike the leaves, vexilla did not undergo photosynthesis.