Which is not true of hydrophytes?
A) Poorly developed root system
B) Thin membranous leaves
C) Poorly developed large air spaces
D) Poorly developed vascular bundle

Hint: Hydrophytes are the aquatic plants which live completely or partially submerged in fresh water. They have aerenchyma. Leaves of the plant can float in water. It can change according to water level. Xylem tissues are not well developed. They have vascular bundles present in their stems. They have flexible stems.

Complete answer:
Hydrophytes are the plants which are found in water. Aquatic plants can be fully or partially submerged in the freshwater. Removal of extra water from their plants occurs through special mechanisms. It has broad leaves with a large number of stomata on their upper surfaces. Hydrophytic plants are mainly of four types: emergent, floating, submerged, and algae.
Xylem of hydrophytes is poorly developed. Vessels in the hydrophytes are completely absent but tracheas are well developed. They have special types of air storage parenchyma called aerenchyma. Cuticles are poorly developed in hydrophytes. Hydrophytes do not have root systems.
Lotus (Nelumbia), Hydrilla, valisineria, Trapa, crow foot and Eichhornia are some examples of hydrophytes.
From the above information we have found that hydrophytes have well developed large air spaces. So the statement “poorly developed large air spaces” is not true about hydrophytes.

Therefore, the correct answer is option C.

Note: Hydrophytes are also found floating on the water surface but in some species the roots remain embedded in the mud. Some of the examples of such plants are: Nymphaea, limnanthemum, Vitoria regia and Euryale ferox. Xerophytes survive under very less availability of water while the mesophytes grow in the environment which is neither very dry nor very wet.