Plant Anatomy: Anatomy of Flowering Plants: Dicot Leaf I Biology for PGT Exams I Free Notes I #KVS #NVS #EMRS #DSSSB #UPPGT #MASTERCADRE #LECTURE CADRE

The vertical section of a dorsiventral leaf through the lamina shows three main parts, namely, epidermis, mesophyll and vascular system.

The epidermis which covers both the upper surface (adaxial epidermis) and lower surface (abaxial epidermis) of the leaf has a conspicuous cuticle. 

The upper epidermis has thick cuticle than lower epidermis, this thick cuticle helps to reflect away excess sunlight.

The abaxial epidermis generally bears more stomata than the adaxial epidermis. The latter may even lack stomata. 

Mesophyll:

The tissue between the upper and the lower epidermis other than veins is called the mesophyll. 

Mesophyll, which possesses chloroplasts and carry out photosynthesis, is made up of parenchyma. It has two types of cells – the palisade parenchyma and the spongy parenchyma. 

The adaxially placed palisade parenchyma is made up of elongated cells, which are arranged vertically and parallel to each other. They contain discoid chloroplast.

In Sciophytes-shade loving plants palisade parenchyma is absent

In Heliophytes-Sun loving plants, it is well developed and many layered

The oval or round and loosely arranged spongy parenchyma is situated below the palisade cells and extends to the lower epidermis. There are numerous large spaces and air cavities between these cells.

They have large intercellular spaces.

So, with spongy mesophyll around the stoma the molecules of Carbon Dioxide penetrated deep and quickly.

Vascular System:

Vascular system includes vascular bundles, which can be seen in the veins and the midrib. The size of the vascular bundles is dependent on the size of the veins. The veins vary in thickness in the reticulate venation of the dicot leaves. 

The vascular bundles are surrounded by a layer of thick-walled bundle sheath cells. The bundle sheath of larger veins shows parenchymatous extensions toward upper and lower surface

The vascular bundles are closed, conjoint and collateral

Xylem is Endarch

Source:  NCERT Biology book class 11

              Plant Anatomy by James D Mauseth

WATCH OUT THE COMPLETE VIDEO:



Chief function of leaves are (ICAR PG Plant Science 2020)

Gaseous exchange and Photosynthesis

Respiration and Photosynthesis

Respiration and Digestion

Respiration and Gaseous Exchange


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