Complete information about the anatomy of dorsiventral leaf

Most dicot plants have dorsiventarl leaves. Transverse section of a dorsiventral leaf shows the following structure:

Epidermis:

There is two epidermal layers, viz. the upper epidermis and the lower epidermis. The upper epidermis is one layered. The cells of the upper epidermis are one barrel-shaped and are compactly arranged. The outer wall of the upper epidermis is covered by a thick cuticle. These cells are devoid of chloroplasts. The lower epidermis is also single layered and is composed of barel-shaped cells which are compactly arranged. The outer wall of lower epidermis is covered by thin cuticle.Stomata are present only on the lower epidermis. Each stoma is surrounded by two guard cells. The guard cells contain chloroplasts.

Mesophyll:

It is present between upper and lower epidermis. It is differentiated into and lower epidermis. It is differentiated into palisade parenchyma and spongy parenchyma. Palisade parenchyma- Palisade parenchyma is present below the upper epidermis. They are two to three layered. These cells are elongated and thin-walled with numerous chloroplasts on their radial walls. The cells are compactly arranged at right angle to the upper epidermis.

Spongy Parenchyma:

Spongy parenchyma lies below the lower epidermis. The cells are isodiametric and thin-walled with numerous chloroplasts. These are loosely arranged with well-developed intercellular spaces. The substomatal cavities below stomata are interconnected with the intercellular space.

Vascular Bundles:

The vascular bundles are present in veins and veinlets of the leaf. Each vascular bundle is conjoint, collateral and closed. Xylem is present towards the upper epidermis and phloem is present towards the lower epidermis. Each Vascular bundle is surrounded by thin-walled parenchymatous bundle sheath. In bigger vascular bundles, the bundles sheath extends on both the sides upon to the epidermis. The sclerenchymatous patches are also present outside the xylem and phloem in case of bigger vascular bundles. Xylem consists of metaxylem, protoxylem and wood parenchyma. Tracheids and wood fibres are absent. The phloem consists of sieve tubes, companion cells and few phloem parenchyma.