Photon-Vegetation Interactions deals with the interaction of electromagnetic radiation with vegetation canopies. The approach to the various aspects is mainly theoretical and consequently the subject is being treated as a special branch of mathematical physics. A major emphasis is on the development of theoretical methods for determining the reflection function of vegetation canopies in optical remote sensing. Furthermore, the coupling of the radiative transfer theory with leaf photosynthesis to evaluate the productivity of vegetation canopies is treated as well as the theory of photon transport in phototropic and other biological media.