Define modification of stems.
Answers
Answer:
SUPPORT:- In some plants, such as grapevine, stems have a thread-like structure present on them called the stem tendrils. These tendrils coil around any rough surface they come in contact with, and thus, provide support to the weak stems of these plants. These tendrils are a modification in the structure of the stem. These are also called climbers or twiners.
STORAGE:- We know that roots are modified to store food. Similarly, in certain plants stems are modified to store food. Such stems grow underground and serve as a source of food for the plant in unfavourable conditions. Examples of such stems are ginger, potato and onion. Can you find features of stems such as leaves (in the form of thin scales) and nodes on these edible stems?
MAKING FOOD:-In deserts and other such places where there is'scarcity of water, the leaves are in the form of spines so that there is no loss ofwater through them. Here, the stem is modified to take over the function of making food. The stems in such plants are green and fleshy.- Stems also store water in these conditions. Examples of such plants are cactus and other desert plants.
Answer:
In some plants the stems are modified to perform the function of storage of food, support, protection and vegetative propagation.
For food storage: Rhizome (ginger), Tuber (potato), Bulb (onion), Corm (colocasia).
For support: Stem tendrils of watermelon, grapevine, cucumber.
For protection: Axillary buds of stem of citrus, Bougainvillea get modified into pointed thorns. They protect the plants from animals.
For vegetative propagation: Underground stems of grass, strawberry, lateral branches of mint and jasmine.
For assimilation of food: Flattened stem of Opuntia contains chlorophyll and performs photosynthesis.