Energy flows from the sun to the earth where some fraction is absorbed by plant surfaces. Plants use some of that energy to drive primary production, but that is a small fraction of the total absorbed energy. Most of the absorbed energy is redistributed back to the surroundings. Following the laws of thermodynamics, energy can be transformed, transferred, or stored, but not destroyed. Thus, energy input from the surroundings must be balanced by an equal and constant output or be stored within the plant’s mass. The requirement for a full accounting of energy transfers and storage, and thus reconciliation of the plant’s energy budget, has been recognized for several decades as an important perspective from which to study biophysics and the evolutionary adaptation of plants to their environment. The “environment” of a plant consists of all scales between the sun and earth; though we may isolate certain components to prioritize the factors that determine energy exchange. The quotes above, by Klaus Raschke and David Gates, two of the pioneers in the field of plant-atmosphere biophysics state in very clear terms, the continuum of space that describes the “environment” with which a plant must exchange energy, and the necessity of “energy accounting” as a means to understand plant function and adaptation.