The leaves interact with the above physical environment in two ways: energy & mass exchange. From the biophysical control aspect, leaves can maintain their temperatures within a narrower range than ambient temperatures, which can be predicted by leaf energy balance theory. We present and predict the existence of crossover temperature by field observation (Fig.1 & fig.2) and approximate Priestley-Taylor. From metabolic processes, the temperature has great impact on plants by enzyme kinetics and CO2 drawdown, but plants can acclimate their plant function traits (fig.3 & fig.4) to responsd to the environment temperature change. The double mass of fundamental biophysics and temperature acclimation from recent vegetation model research, therefore leaf temperature and acclimation of traits should be key variables included in future DGVMs.