Protective tissues includes epidermis & cork. Epidermis is basically a simple permanent tissue, protective in function. It forms one-cell-thick covering over all the parts of plant.
⇝ Characteristics of Epidermis :
Epidermis is formed of living cells, arranged in a single layer.
In aerial parts, epidermis is covered with a waterproof and noncellular waxy covering called cuticle.
Cells form a continuous layer, but in leaves epidermis has small openings called stomata.
Each stoma is guarded by a pair of bean-shaped guard cells which govern opening & closing of stomatal aperture.
⇝ Functions of Epidermis :
Epidermis protects the underlying tissues from mechanical injury, chemicals & infection.
Cuticle of epidermis protects against water loss & desiccation. It checks the rate of transpiration & evaporation and prevents wilting.
Stomata in the epidermis of leaves help in gaseous exchange during respiration & photosynthesis.
