Obviously, this doesnt happen, and let's figure out why. Energy Budget of a leaf I mentioned with reference to ag that water is major factor limiting production. This strongly influences leaf temp. The key is that, like sweat from an animal, evaporation from a plant leaf carries off a lot of heat. This energy in evaporation from leaf surfaces is called latent heat.
Enzymes function best over a limited temperature range.
For example, high temperature increases respiration exponentially and burns off carbon. This is sometimes called sensible heat . This differs from conduction , where heat is transferred by direct contact with the leaf, or latent heat which is heat lost by evaporation . It lies with the range of 0-1. This is how easily the plant absorbs heat.