The three separate excerpts quoted above from the classic book on plant canopies and their radiation regime by the biophysicist, Juhan Ross, underscore three aspects of past studies of the solar radiant flux at the canopy scale. First, description of the architecture of plant canopies is a central activity of researchers interested in controls over plant productivity and its relation to climate. Second, the relation of canopy architecture to the distribution of solar radiation within the canopy is complex. Third, in large part due to that complexity, researchers have sought ways to simplify descriptions of canopy structure and radiative transfer using statistical models. In this chapter we will use these three fundamental tenets as the context within which to explore canopy structure and its relation to the capture of solar radiation.