The adaptation of plants to a continuously changing environment is approached as an expression of an optimisation strategy, dictated by the thermodynamic demand for minimal entropy production. A logic bridge between the theoretical predictions of open system thermodynamics and the phenomenology of experimentally investigated aspects of the behavior of plants is established, in terms of the J-K-B-Trilogy, and further applied for the photosystem II of the photosynthetic apparatus. The chlorophyll a fluorescence kinetics, analysed according to the Theory of Energy Fluxes in Biomembranes , lead to a constellation of structural and functional parameters, thus providing a quantification of a system behaviour. A case study in Camellia leaves is then treated on the multiparametric response of the system to short-term changes of the light intensity was studied. It is demonstrated that this response is indeed in accordance with the theoretical predicitons.