The epidermis is the outermost layer of cells in both leaves and stems. The cells of the epidermis are typically thin and flattened, and they are tightly packed together. This arrangement of cells helps to protect the plant from water loss and from damage by pests and diseases.

The epidermis of leaves is also responsible for the exchange of gases between the plant and the atmosphere. The cells of the epidermis contain chloroplasts, which are organelles that use sunlight to convert carbon dioxide and water into sugar and oxygen. The oxygen that is produced by photosynthesis is released into the atmosphere through the stomata, which are small pores in the epidermis.

Other tissues

The other tissues of the leaf have different shapes of cells because they perform different functions. For example, the cells of the mesophyll are thin and elongated, and they contain numerous chloroplasts. This arrangement of cells allows for the maximum amount of sunlight to be absorbed by the plant for photosynthesis.

The cells of the vascular bundles are long and narrow, and they are responsible for transporting water and nutrients throughout the plant. The cells of the xylem, which is one of the two types of vascular tissue, are hollow and they allow water to move up from the roots to the leaves. The cells of the phloem, which is the other type of vascular tissue, are filled with cytoplasm and they transport sugar and other nutrients from the leaves to the rest of the plant.

The different shapes of cells in different tissues of the leaf are a reflection of the different functions that these tissues perform.