Nymphaea has seven species already catalogued in the flood prone areas of the Brazilian Pantanal. However, some species remain difficult to identify and descriptions of the anatomy of vegetative organs are an important tool for infrageneric separation to aid in group taxonomy. The species collected in the Pantanal and prepared according to the usual techniques for anatomical studies showed similar structural characteristics, and data on the arrangement of vascular bundles in the midrib and petiole, as well as the form and distribution of sclereids, were consistent. Nymphaea oxypetala stands out from the other evaluated species for having a greater number of differential characters, including angular collenchyma and the absence of bicollateral bundles in the petiole. Nymphaea lingulata stands out as the only species to feature bicollateral bundles in the leaf blade. The results, summarised in the dichotomous key, facilitate the identification of species that use the flower as the main differentiation, but are in a vegetative stage.
anatomical differences; aquatic macrophytes; dichotomous key; Pantanal
