Question

Respiratory roots and viviparous reproduction are the characteristics of
A. Hydrophytes
B. Xerophytes
C. Mesophytes
D. Mangroves

Answer 1

Hint: Vivipary means the seed germinates while it is still attached to the plant. Further, the seedling grows, emerges from the fruit and is eventually dispersed.

Complete answer:
Hydrophytes are plants which live in wet places or in water either partly or wholly submerged. The roots are generally small and feathery. There is reduction of roots so that water can diffuse directly into leaves. They are modified to take in oxygen from the water. Since the plants are generally submerged inside water, there is less need for a long and thick root structure. Root airs are generally absent instead they have root pockets. The main function of the roots is for anchorage in the water and not for absorption of water. Eg. Hydrilla, lotus, etc.
So ‘option A’ is incorrect.
Xerophytes are plants that can survive in environments where there is little water or moisture. They grow generally in dry regions like deserts or an ice or snow-covered region in the Alps or the Arctic. They have well developed roots that penetrate deep into the soil or can be either close to the surface of the soil. Roots absorb water and have the ability to store them. Eg. Cacti, pineapple, etc.
So ‘option B’ is incorrect.
Mesophytes are plants that can survive neither in dry nor in wet environments. They show both the features of xerophytes and hydrophytes. They generally grow under favourable conditions such as shaded forest areas or sunny meadows or fields. They have well-developed root systems, either fibrous roots or long taproots. Eg. Corn, clover, etc.
So ‘option C’ is incorrect.
Mangroves are salt-tolerant trees and are known as halophytes. They have specialised roots above the ground known as breathing roots or pneumatophores. These roots consist of several pores through which oxygen enters into the underground tissues. The reason behind that under the ground, the soil is not able to provide enough oxygen to the roots. Therefore, the root system outgrows aerial roots which grow vertically above the soil.
They also show viviparous reproduction which means the seed germinates while it is still attached to the mother plant.

Hence, the correct answer is option (D).

Note: Mangroves have specialised types of roots above the ground known as breathing roots or pneumatophores. They are also called halophytes. They also show a viviparous mode of reproduction.