Pneumatophores are present in

Concept

Pneumatophores are specialized, negatively geotropic respiratory roots that grow upward from oxygen-poor, waterlogged soil.

Their exposed portions carry pores for gas exchange, supplying air to the underground root system.

Application

Pneumatophores occur in mangrove halophytes such as Avicennia and Sonneratia. They also occur in some marsh or swamp hydrophytes whose roots remain in oxygen-poor, waterlogged substrate.

Contrast

• Hydrophytes include water- or marsh-adapted plants; some swamp hydrophytes develop breathing roots.

• Xerophytes are adapted to dry conditions and water scarcity, which is a different environmental stress.

• Halophytes tolerate saline habitats; mangrove halophytes characteristically develop breathing roots in poorly aerated mud.

• Both hydrophytes and halophytes therefore supply valid instances among the listed groups.

• The feature is not absent from all listed groups because two listed groups contain examples.

Cross-check

The decisive condition is an oxygen-poor, waterlogged root zone, which can occur in both swamp hydrophytes and mangrove halophytes. Therefore, the answer is More than one of the above.