Check sibling questions

 

Observe the outermost layer of cells in plants

What do you notice?

This is the single layer of cells called epidermis .

They are flat with outer and side walls are thicker than the inner wall

It is present all through the plant and protects the plant parts .

Since it has to protect, these cells do not have intercellular spaces .

The epidermal cells on the aerial surface (part facing outward) secrete a waxy, water-resistant layer .

This aids :

  • Protection against loss of water
  • Mechanical injury 
  • Invasion by parasitic fungi

The epidermis is thicker in dry areas to protect plants from water loss. They also have a layer of chemical substance called cutin which gives the plant waterproof quality .

Stomata

Observe this image;

 

Look at the small pores present between the epidermal cells .

These are called stomata .

  • The pore called stomata is enclosed by two kidney-shaped cells called guard cells .
  • Exchange of gases (respiration in plants) takes place through stomata.
  • Transpiration (loss of water in the form of water vapour) also takes place through stomata

There are root hairs extending from the epidermal layer .

Why is this so?

 

The root epidermis is responsible for water absorption

To increase surface area of absorption , they bear long hair-like structures called root hair.

Branch

Have you observed the outer layer of a branch of a young plant and that of a tree?

 

Why are they different?

The outer protective tissue of plants undergo certain changes with time

A strip of secondary meristem replaces the epidermis of the stem. 

Cells on the outside are cut off from this layer to form several-layer thick cork (bark of the tree)

 

  • Cork cells are dead
  • Cells are compactly arranged
  • They do not have intercellular spaces
  • They have a chemical called suberin in their walls
  • Suberin makes sure that gases and water cannot pass through
  • Thus it protects the plants from mechanical injury and water loss by evaporation.

Maths Crash Course - Live lectures + all videos + Real time Doubt solving!

Ask a doubt (live)
Maninder Singh's photo - Co-founder, Teachoo

Made by

Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 12 years and a teacher from the past 16 years. He teaches Science, Economics, Accounting and English at Teachoo