We found amazing amounts of mistletoe in the Cotswolds. I've just been teaching the more detailed version of the photosynthesis reaction for the first time. The mistletoe must be using the light at this time of year when the leaves are off the host tree. The light dependent reaction uses the photon energy to split water. The hydrogen is taken to reduce NADP. The energy is also used to add a phosphate group to ADP to make ATP. NADPH and ATP are then the energy providers for the Calvin Cycle which turns carbon dioxide into sugar.