Anatomy of Mangifera indica Dicot Leaf | Biology

Anatomy of Mangifera indica – Leaf (Family – Anacardiaceae):

Following tissues are visible in the transverse section of the material:

Epidermis:

1. An epidermal layer is present on the upper as well as lower surfaces.

2. One celled thick upper and lower epidermal layers consist of barrel shaped, compactly arranged cells.

3. A thick cuticle is present on the outer walls of epidermal cells. Comparatively, thick cuticle is present on the upper epidermis.

4. Stomata are present only on the lower epidermis.

Mesophyll:

5. It is clearly differentiated into palisade and spongy parenchyma.

6. Palisade lies just inner to the upper epidermis, and composed of elongated cells arranged in two layers.

7. The cells of palisade region are compactly arranged and filled with chloroplasts. At some places the cells are arranged loosely and leave small and big intercellular spaces.

8. Palisade cells are arranged at a plane at right angle to the upper epidermis, and the chloroplast in them are arranged along their radial walls.

9. Parenchymatous cells are present above and below the large vascular bundles. These cells interrupt the palisade layers and are said to be the extensions of the bundle sheath.

10. Spongy parenchyma region is present just below the palisade and extends upto the lower epidermis.

11. The cells of spongy parenchyma are loosely arranged, filled with many chloroplasts and leaves big intercellular spaces.

Vascular Region:

12. Many large and small vascular bundles are present.

13. Vascular bundles are conjoint, collateral and closed.

14. Each vascular bundle is surrounded by a bundle sheath.

15. Bundle sheath is parenchymatous and in case of large bundles it extends upto the epidermis with the help of thin walled parenchymatous cells.

16. The xylem is present towards the upper epidermis and consists of vessels and xylem parenchyma. Protoxylem is present towards upper epidermis while the metaxylem towards the lower epidermis.

17. Phloem is situated towards the lower epidermis and consists of sieve tubes, companion cells and phloem parenchyma.

Identification:

(a) 1. Presence of expanded portion or blade.

2. Presence of mesophyll.

3. Bundle sheath is present. (Leaf)

(b) 1. Upper and lower epidermal layers are clearly distinguishable.

2. Mesophyll is clearly differentiated into palisade and spongy parenchyma.

3. Stomata only on the lower surface. (Dorsiventral Dicot Leaf)