Acrocomia aculeata is an oleaginous palm widely distributed through the tropical and subtropical Americas that shows significant potential for agroindustrial use. Studies of floral structures can contribute to our knowledge of the evolutionary diversification of this genus and ecological aspects of its species as well as assist management and domestication programs. With the objective of characterizing the morphoanatomy of the flowers of A. aculeata, 20 inflorescences were collected in each of three natural populations growing in the northern region of Minas Gerais State, Brazil. Flowers at anthesis were evaluated biometrically and using standard plant anatomical procedures, and observed under light and scanning electron microscopy. The flowers showed wide biometric variability that was influenced by the collection area, the individuals examined, and the positions of the flowers on the inflorescence. Staminate flowers can have two whorls of petals, small anthers, and vestigial structures, with the development of an infertile carpel and rudimentary ovules. Defenses against herbivory include the presence of raphides in the anthers and pistillate flowers, fiber bundles, stegmata, and idioblasts containing phenols and raphides. Pollinators are attracted by the liberation of intense odors produced by osmophores located in the corolla, with pollen being the principal resource offered. Phenotypic plasticity, the structures involved in defending against herbivores and attracting pollinators, the numbers of flowers, and flowering synchrony contribute to the reproductive success of this species. The short period during which the stigmas remain receptive determines synchronous fertilization within the inflorescence.