A model of the energy exchange within a canopy of leaves is presented in terms of three sets of equations. The sums of radiant, sensible, and latent heat exchange in several strata of the canopy are set equal to zero. Next, the potentials for the exchange of latent and sensible heat are related to the warming of the leaves. Finally, the difference in potential between adjacent strata are related to the diffusive resistances of the air within the canopy, the boundary layer, and the stomata, and to the fluxes of latent and sensible heat. This system of simultaneous linear equations is solved algebraically for the exchange of latent and sensible heat by each stratum of the canopy, for the leaf temperature of these strata, for the exchange of latent and sensible heat by the soil, and for the storage of heat within the soil. The temperature and humidity above and below the canopy, the absorption of radiation within the canopy, and the several diffusive resistances must be specified. Observations of the exchange of energy and the microclimate within a pine canopy are mimicked by the model. Nine strata are demonstrated to be an adequate number. Calculations with the model explain the effect of stomatal changes upon the evaporation from a forest.