CBSE Class 9 Answered

how the epidermis of roots , stem and leaves are modified?explain with example.

Asked by sbidipak | 21 Jun, 2017, 06:33: PM

Expert Answer

The epidermis is an outer protective covering tissue of plant roots, leaves, and stems of nonwoody plants. It contains closely packed epidermal cells.

Modifications of epidermis of roots, stem and leaves:

Walls of epidermal cells are covered with a waxy cuticle to minimise water loss and protect against bacteria.
In roots, certain epidermal cells are modified into root hairs that increase surface area of the root for absorption of water and minerals and help to anchor the plant firmly in place.
Protective hairs of a different nature are produced by epidermal cells of stems and leaves.
Epidermal cells may be modified as glands that secrete protective substances of various types.
In leaves, particularly the lower epidermis, specialized epidermal cells (guard cells) form microscopic pores (stomata) and regulate gas exchange between interior and exterior of a leaf.

The roots, stem and leaves of plants are modified for storage of food or protection to the plant.

Root modifications
Adventitious and prop roots	E.g. Maize
Pneumatophores	E.g. Mangroves
Velamen roots	E.g. Orchids
Fleshy roots	E.g. Carrot
Stem modifications
Tendrils	E.g. Grapes
Cladophylls	E.g. Asparagus
Thorns	E.g. Bougainvillea
Storage stems	E.g. Onion bulbs
Runners/Stolons	E.g. Strawberry
Leaf modifications
Spines	E.g. Cacti
Bracts	E.g. Bougainvillea
Carnivorous leaves	E.g. Venus flytrap
Tendrils	E.g. Peas
Plantlets	E.g. Kalanchoe