Plant nastic movements follow unique plant behavioural patterns that synchronize with external cues. Because the foliar nastic motions of Portulaca species are solely circadian, it would be fascinating to explore whether and how melatonin governs these movements. Analyzing morphological and anatomical traits in accordance with stomatal behaviour offers visual data regarding the plant species’ gnosophysiology and ecology. Morphometric and anatomical features provide clues and even prove the function of pleiotropic external stimuli. The current study seeks to understand how exogenous melatonin affects the foliar nastic movements in Portulaca oleracea. According to the findings, melatonin functioned as an intracellular hydrodynamic controller by navigating idioblast, crystal densities, and stomatal behaviour. Thus this hormone can be one of the auxiliary internal regulators of turgor pressure, thereby assisting P.oleracea’s characteristic foliar nastic movement that is circadian. The timepoint study at specific zeitgebers indicated that abiotic variables alter the endogenous melatonin concentration of P.oleracea. The idioblast and crystal torques and their angular momentum must be investigated further to calculate the hydraulic forces at work in the leaf lamina. This could decrypt melatonin’s pleiotropic action and the underlying mechanism of foliar nastic motions of other plant species.