Question

Explain modification in stem, roots and leaves.

Answer 1

Depending on the location, climatic conditions plants develop survival mechanisms. These survival mechanisms include modifying their parts to perform additional function. Different parts of the plant like root, stem and leaves undergo modification to perform additional functions.

Complete answer:
Plant has different parts like root, stem and leaves. Each of them has a separate function to perform. In special cases, these structures get modified to facilitate different functions in the plants.
The main job of roots is to absorb and transport water. However in special cases, roots may get modified to store food, help in respiration and provide support. Depending on the need and type of plant, the adventitious or tap roots may be modified. Example- Carrot, Banyan tree.
The primary function of the stem is to produce and support lateral appendages and conduct food and minerals. However, it gets modified to perform additional functions such as storage of food, protection from browsing animals, perennation, proliferation and propagation. Example- Potato, strawberry, passion flower.
Leaves are green structures of plants mainly involved in photosynthesis. Besides photosynthesis and transpiration, they undergo modifications to provide support, to manage water loss by reducing transpiration. Example- Sweet pea, Cat’s nail.

Additional information:
The modifications of different plant parts with examples are given below:

Modifications of tap root:
For food storage- Carrot, Beet root
For respiration: Pneumatophores- Mangroves

Modifications of adventitious roots
For food storage- Sweet potato, Asparagus
For mechanical support: Prop roots- Banyan tree, Stilt roots- Maize, Climbing roots- Money plant
For special function: Epiphytic roots- Orchids, Sucking roots- Dodder

Modifications of stem:
Underground modifications: (for food storage, perennation and vegetative propagation)
Rhizome- Ginger, Bulb- Onion, Stem tuber- Potato, Corm- Colocasia
Sub-aerial modifications: (for perennation and vegetative propagation)
Runner- Lawn grass, Stolon- Strawberry, Offset- Pistia, Sucker- Mint
Aerial modifications: (for support, photosynthesis)
Stem tendril- Passion flower, Thorn- Citrus, Phylloclade- Opuntia, Cladode- Asparagus, Bulbils- Dioscorea

Modifications in leaf:
Leaf spines- Acacia, leaf tendrils- Sweet pea, Leaf hooks- Cat’s nail, Phyllode- Acacia Auriculiformis

Note: Modifications seen in various parts of the plant appear as adaptations.These modifications increase the survival chances of the plants. Other than stems, roots and leaves also get modified for adapting.