Structures of the leaf

Other than the vascular tissues, there are other structures of the leaf which help in photosynthesis.

Waxy Cuticle: It covers the whole leaf and being transparent, it allows light to enter the leaf for photosynthesis. Also, it reduces evaporation through the leaf.

Upper epidermis: It is one-cell layer thick and does not contain chloroplasts for photosynthesis.

Palisade mesophyll cells: It contains the most chloroplasts, lying just below the upper epidermis of the leaf. They are closely packed to allow more cells and more chloroplasts to be near the surface. The small intercellular spaces in between them allow gaseous exchange to occur.

Spongy mesophyll cells: It has less chloroplasts than the palisade mesophyll cells and larger intercellular spaces. They store carbohydrates which are products of photosynthesis. Dissolved carbohydrates diffuse into the phloem to be transported to the rest of the plant.

Lower epidermis: It has guard cells that form stomata which allow gaseous exchange to occur. The gaseous exchange which is the intake of carbon dioxide and the release of oxygen is essential for photosynthesis. In addition, the guard cells regulate the water balance in the plant.

4. Vascular Bundle 7. Sieve tube

The vascular tissue system is important in transport. The vascular tissue system is composed of the xylem, which transport water and dissolved minerals, and phloem, which transports sucrose, nitrogen containing compounds and hormones.

The phloem is found on the lower side of the vascular bundle. The xylem in the vascular bundle is found on the upper side of the vascular bundle so that water transported to the leaf cells can diffuse into the chloroplasts faster.

The vein is supported by fibres also known as sclerenchyma, which keeps the shape of the leaf flat.