Studies have shown that the water conduction function and gas exchange function of the edge of the plant leaf are not as good as that of the middle part of the leaf. Take a certain open-air tropical plant alocasia as an example, its leaf diameter can reach 1 meter. The high temperature of 8.8 degrees celsius causes high temperature burns on the edges of some leaves and dry. 
scientists believe that this phenomenon limits the continued expansion of the leaf area. Of course, there are relatively few giant leaf plants in nature.
Reduced water conduction and gas exchange function of plant leaves will inhibit heat dissipation