To minimize the effects of abiotic factors in aquatic systems, aquatic plants feature efficient anatomical structures which are essential for successful colonization. The macrophytes show great plasticity in vegetative organ development, and such plasticity reflects environmental changes. Specifically, since Nymphaea gardneriana can inhabit completely different environments, featuring fully submerged leaves in rivers and floating leaves in lakes, this work aimed to compare the anatomy of these two kinds of leaves. Submerged plants show reddish leaves with a smaller and thinner leaf blade and different epidermal thickening in the midrib. Submerged leaves have a smaller stomatal density, but a greater density of hydropotes, which are present on both surfaces. They present a regular chlorenchyma and one to two vascular bundles in the midrib. On the other hand, floating leaves are green with thin-walled epidermal cells; hydropotes are found exclusively on the abaxial surface; a typical palisade chlorenchyma can be observed with two vascular bundles in the midrib. Studies indicate that the size, flexibility, color, and leaf anatomy are responses to factors such as flow, nutrients, turbidity of the water and light availability. The phenotypic variations of Nymphaea gardneriana that occur in fully submerged compared to floating leaves indicate that this species adjusts leaf development in response to physical variations in the environment.