Plants respond to variation in luminosity leading to the existence of distinct leaf traits in plants that inhabit the understory, edge, and canopy of tropical forests. In the present work, the long-life leaves of Ouratea castaneifolia Engl. (Ochnaceae) in forest edge and understory were evaluated. Leaves of 20 individuals were collected from each habitat. Median regions of leaves from the third node were fixed in FAA. Freehand-cut transverse sections were stained in astra blue and safranin. The thickness of tissues, leaf area, specific leaf mass, and relative water content were quantified. Quantum yield of photosynthesis was measured by Fv/Fm, and instantaneous light response curves were performed to extract ETRmax, PARsat, and ∆F/Fm′sat. Quantification of photosynthetic pigments was also performed. Leaf area was lower at the forest edge, while the specific leaf mass was higher. No structural differences or differences in relative water content were observed between individuals of the two environments. The thicknesses of the cuticle on the adaxial surface, the epidermal cells on the abaxial surface, and the palisade and spongy parenchyma were greater in individuals at the forest edge. The values of Fv/Fm were around 0.8 in the predawn. In midday, higher values of Fv/Fm were observed in individuals located in the understory. Individuals of the understory had higher levels of chlorophyll a, chlorophyll b, and total chlorophyll. The morphological traits were the most plastic, but modulations in both morphology and pigment concentration may explain the maintenance of a similar predawn quantum yield between environments.