Question

Sunken stomata are adaptation of which category of plants-
A. Hydrophytes
B. Sciophytes
C. Xerophytes
D. Halophytes

Answer 1

Hint: The term sunken means hidden so sunken stomata are the type of stomata that are hidden or not directly exposed to the surface. They are found below the leaves and the epidermis in the plants. These stomata are present in a small pit.

Complete answer:
Sunken stomata are found sunken in the leaves. These are present in a small pit embedded in the inner leaf layers. These stomata have developed as an adaptation for plants growing in water-scarce conditions. They protect the loss of water from the plants by preventing the escape of water vapor due to the air currents or transpiration. The small pit size hinders the escape of water. The stomata are also covered by trichomes and cuticle.
This adaption is majorly seen in the plants growing in dry and arid conditions as a significant amount of water is lost in the process of transpiration and from drying winds. This helps these plants to sustain in those dry conditions.

Let us analyze the options to find the correct answer

Option A: In Hydrophytes, the stomata are either submerged or they do not have stomata. If present, the stomata are lined by the cuticle. Therefore, this is the incorrect option.
Option B: In Sciophytes, i.e., the shade-loving trees, the stomata are present on the surface or on the same level. Therefore, this is the incorrect option.
Option C: In Xerophytes, as a part of special adaptation, sunken stomata are found, majorly on the lower surface of the leaf. Examples are Nerium, Pine, Acacia, etc. Therefore, this is the correct option.
Option D: In Halophytes i.e, plants living in the saline condition, have the stomata present on the upper surface of the leaf. Therefore, this is the incorrect option.

Hence, the correct answer is option (C)

Note: In Xerophytes, to prevent the loss of water and compensate for the absence of water in the environment, several adaptations have taken place. They have deep and spreading roots and can store water in their stem. The trichomes present above the stomata produces a moist environment that helps to reduce water loss and creates a shield.