Question

Why the leaves in cactus plants are reduced to spines?

Answer 1

Leaves: Leaves are thin, flat organs responsible for photosynthesis in the plants. It develops laterally at the node. They have been modified into different forms to perform specialized functions. For eg: Cactus leaves modified into needle-like structures known as spines.

1. The cactus plant is a desert plant. And in desert area, there is scarcity of water.
2. As we know the process of transpiration, in which water in the form of water vapour gets lost in the atmosphere from the small pores present in leafs called stomata.
3. So, if this process continues for a long time in desert plants, then all the water get lost from the plant body.
4. Therefore, to reduce the loss of water by the process of transpiration the leaves get reduced to spines.
5. As the spines has small surface area so there will be less transpiration and thus help desert plants to avoid excess loss of water from the plant body.
6. The spines act as defensive structures.