The genus Stenanona comprises 15 species distributed from Mexico to Colombia. Stenanona flagelliflora is the only species in which the reproductive structures are found on the flagellum, a unique phenomenon in the flora of Mexico. Our objective is to recognize and describe anatomical features of flowers and fruits that contribute to the systematics of the species. We collected floral buds in three different stages of development (buds I, II, and III), flowers at anthesis, and immature and mature fruits in the ecological reserve of the ejido Adolfo López Mateos, Catemaco, Veracruz, Mexico; the samples were fixed in formalin-acetic acid-alcohol (FAA), cut, stained, and mounted using conventional histological techniques. The receptacle has numerous vascular bundles distributed in two cylinders: the perianth is trimerous; it has 32 stamens arranged in four whorls; the anthers have a deltoidshaped extension of connective tissue; the gynoecium has 5-7 free carpels. Bud II showed a bitegmic and crassinucellate ovule with four layers of the outer integument and two of the inner integument, an ovary with trichomes on the outer epidermis and reduced style, and anthers in different stages of development. Bud III showed epidermis with bulliform cells in the style and stigma. The fruit is of berry type; the ripe fruit shows longitudinal series of fibers across the mesocarp. The endosperm is ruminate; the embryo is small and undifferentiated. These features are common in the Annonaceae family; however, the number of integumentary layers in the ovule and the presence of papillae on the style and stigma are novel characters.