Microscopic characterization of American oil palm ( Elaeis oleifera (Kunth) Cortés) floral development

•First detailed report about the inflorescence and flower development of Elaeis oleifera.•Showed that E. guineensis and E. oleifera have the same pattern of inflorescence and flower development.•Generated the basis for preparing E. oleifera chromosome spreads to be used in cytogenetic studies using GISH/FISH experiments.•Confirmed high degree of homology between these two species via a GISH experiment.•Showed that leaf +14 is the ideal stage for collecting haploid cells for tissue culture aiming the production of haploid plants.