Internal Construction Of A Leaf

Internal Structure of a Leaf:

When the leafage is cutting inward cross-section together with seen nether a microscope, the below structures are seen:

Figure: Internal Structure of a Leaf

1. Cuticle:

Cuticle is a transparent waxy layer covered on the upper surface of the leaf

Cuticle is made upwards of wax which is secreted past times the epidermal cells

2. Epidermis:

Epidermis is a unmarried layer of cells on the upper together with lower surface of the leaf.

The epidermal cells of the leafage don’t comprise chloroplast.

Leaf epidermis keeps the leaf’s shape.

Epidermis of the leafage is divided into, upper epidermis together with lower epidermis

(A) Upper epidermis:

Upper epidermis is flora on the upper surface of the leafage together with tin live seen when the leafage is cutting inward cross-section together with observed nether microscope.

Cells of the upper epidermis are transparent

No stomata are present

(B) Lower epidermis:

Lower epidermis is flora on the lower surface of the leafage together with tin live seen when the leafage is cutting inward cross-section together with observed nether microscope.

Stomata are present

3. Mesophyll tissue:

Mesophyll is the tissue betwixt upper together with lower epidermis of the leaf

Mesophyll tissue consists of:

(A) Palisade cells (palisade mesophyll cells) ad

(B) Spongy cells (spongy mesophyll cells)

(A) Palisade Mesophyll:

Palisade cells are elongated cells together with box-like shape

Palisade cells are flora below the upper epidermis

Palisade cells are closely packed together to absorb maximum light.

Palisade cells comprise maximum total of the leaf’s chloroplasts

Palisade cells are the principal percentage for photosynthesis inward the leaf

Palisade cells have carbon dioxide past times the diffusion from air spaces inward the spongy mesophyll.

Chloroplasts inward the palisade cells are able to motion inside the cytoplasm.

During dim light, chloroplasts inward the palisade cells motion to the upper parts of the jail mobile telephone allowing them maximum absorption of light.

In vivid light, chloroplasts inward the palisade cells motion to the lower parts of the jail mobile telephone for protection from the bleaching effects of intense light.

(B) Spongy Mesophyll:

Spongy cells are irregularly shaped cells alongside large air spaces betwixt them

The air spaces betwixt spongy cells are known equally intercellular air spaces.

Air spaces betwixt spongy cells permit gaseous central inward the leaf.

Spongy cells permit of gaseous central inward the leaf.

Spongy cells comprise viewer chloroplasts

(4) Vascular bundles:

This is the leafage vein, made upwards of both xylem and phloem.

Xylem vessels bring H2O together with minerals to the leafage cells.

Phloem vessels transport sugars together with amino acids away from the leafage cells through the a procedure called translocation.

They likewise supply back upwards for the leaf

(5) Stomata together with Guard Cells:

Stomata are tiny pores flora at the lower epidermis or underside of the leaf.

Stomata are ever opened upwards during twenty-four hr menses fourth dimension together with unopen inward the black time.

Each stoma is surrounded past times a twosome of guard cells.

Guard cells are twosome of cells that environment each stoma.

Guard cells command whether the stoma is opened upwards or closed.

 Stomata opening during twenty-four hr menses light

1. Potassium ions (K⁺) motion into the guard cells
2. Solute concentration inward the guard cells increase
3. Water moves into the vacuoles of the guard cells (Endosmosis of water)
4. The guard cells expand together with conk turgid
5. The stomata open

 

Figure: Mechanisms of Stoma Opening

Stomata closing during night/dark time

1. Potassium ions (K⁺) motion out of the guard cells
2. Solute concentration inward the guard cells decrease
3. Water moves out of the vacuoles of the guard cells (Exosmosis of water)
4. The guard cells shrink inward size together with conk flaccid
5. The stomata close

Figure: Mechanism of Stoma Closing

Figure: Internal Structure of a Leaf