Surface area is very important to plants because they do not have a lot of internal transport mechanisms, and those they do have work rather slowly. Most plant leaves are thin and broad for this reason; a flattened leaf shape creates a high surface area to volume ratio. This helps the plant resolve a paradox: Plants need to capture as much sun as possible each day, but if the interior of the leaf overheats from too much sun.the leaf will die. Broad leaves allow the plant to receive a lot of sunlight, while the thin profile of each leaf means that any cell is only a short distance from a stoma, so that water can evaporate rapidly and keep the leaf cooler inside. So having a large surface area alows the leaf to take in the maximum amount of sun while simultaneously undergoing the maximum amount of evaporative cooling.