The internal structure of a leaf consists of three main tissues:
- The epidermis ( the upper and lower epidermis)
2.The mesophyll consist of palisade and spongy mesophyll
3.The vascular bundle consists of mid –rib and veins
The epidermis is a single layer of closely packed cell found both on the lower and upper surface of the leaf. The epidermis is lined with cuticle which prevent too much evaporation of water and protect the inner cell from mechanical damage and diseases. The mesophyll is made up of parenchyma cell. The tissue between the upper and lower epidermis is called mesophyll.
The palisade mesophyll consist of one or two layers of elongated cell closely packed. The cell contains numerous chloroplast which are used for photosynthesis. The spongy mesophyll is made up of irregular cells that are loosely packed with lots of intercellular air spaces, air diffuse into the space. The carbon (iv) oxide is absorbed for photosynthesis and oxygen is used respiration. The spongy cell contain fewer chloroplasts.
The mid- rib and vein are the vascular tissue consisting of xylem and phloem surrounded with few parenchyma. The stomata are the opening in the epidermal layer of leaves through which air passes in and out of the leaves, the opening and closing of the stomata are guarded by guard cell