Why… are leaves different sizes?

There are hundreds of thousands of different plant species in the world and their leaves can vary from really tiny to gigantic. For example, banana plants have leaves that can grow up to 2.7 metres long. Botanists (scientists who study plants) have always wondered why leaves are different sizes. One of their theories is that tropical plants grow larger because there is more water in the air and soil in their native countries. This is the perfect environment for plants to grow. Another theory suggests that plants that see more sunshine have smaller leaves, whereas plants that are in the shade have larger leaves. This is because the larger leaves need more surface area to soak up more of the Sun’s rays.