Mangroves of the type represented by Avicennia nitida may produce thousands of air roots or pneumatophores, which protrude from the mud around the base of the tree. The stilt roots of Rhizophora mangle have lenticels on the surface, which are connected by air spaces to roots buried in the mud.

Rhizophora is a genus of tropical mangrove trees, sometimes collectively called true mangroves. The most notable species is the red mangrove ...

Rhizophora is a genus of mangrove plants that are adapted to live in saline coastal environments. These plants have several unique features that help them survive in their habitat. One of these features is the presence of pneumatophores.

Pneumatophores are specialized aerial roots that grow vertically from the underground parts of the plant. They emerge above the surface of the water and help in respiration. These roots have small pores called lenticels through which gases like oxygen can enter the root system. This adaptation allows Rhizophora plants to obtain sufficient oxygen even in waterlogged soils.

Another type of root modification seen in Rhizophora is the presence of prop roots. Prop roots are thick, woody roots that emerge from the lower part of the stem and grow vertically downwards into the soil. These roots provide additional support to the plant, especially in areas with strong tidal currents. They anchor the plant firmly in the substrate and prevent it from being uprooted by the force of the waves.

Stilt roots are another type of root modification seen in Rhizophora plants. These roots grow diagonally from the lower part of the stem and extend in a horizontal direction. They also provide additional support to the plant and help it withstand the forces exerted by the water.

Modified roots in Rhizophora plants serve various functions such as respiration, support, and anchorage. However, the correct answer to the question is option 'A' - pneumatophores. Pneumatophores are the most characteristic and well-known root modification in Rhizophora plants. They play a crucial role in the respiration of the plants by providing a direct pathway for the exchange of gases between the atmosphere and the underground parts of the plant.

In conclusion, Rhizophora plants possess various root modifications, including pneumatophores, prop roots, and stilt roots. These modifications help the plants adapt to their saline coastal habitats by enabling respiration and providing support and anchorage. However, the correct answer to the question is option 'A' - pneumatophores.