Which is NOT an adaptive feature of hydrophytes?

Analyze the question: Hydrophytes are plants that live in water (e.g., water lily, water lettuce, hyacinth). We need the option that is NOT an adaptive feature of them.

Concept: Hydrophytes have these typical adaptations:

• Aerenchyma (air spaces) in stems and leaves for buoyancy and gas exchange.
• Broad, flat leaves that float and expose a large surface area to light. Stomata are on the upper surface, and transpiration is not a problem because water is abundant.
• Reduced root system, since the whole plant can absorb water and dissolved minerals directly through its surface. Roots mainly serve as anchors or stabilisers.
• Thin or absent cuticle, because there is no need to conserve water. Some floating leaves have a slight waxy layer on the upper surface to repel water and keep the stomata clear.

Going through the options:

• A. Air spaces for buoyancy: a true adaptation.
• B. Broad leaves to enhance transpiration: broad leaves are a real hydrophyte feature, and a hydrophyte can lose water freely, so this is acceptable.
• C. Extensive root system for absorption of water: this is NOT an adaptation. Hydrophytes are surrounded by water, so they have reduced, poorly developed roots. An extensive root system is a feature of xerophytes and mesophytes, which must search for water.
• D. Fibrous roots: a typical hydrophyte root type (e.g., water hyacinth has a mass of fibrous roots), so it is acceptable.
• E. Waxy cuticle to prevent wetting: found on the upper surface of floating leaves, so it is acceptable.

Answer: The feature that is not an adaptation is the extensive root system for water absorption.

Exam tip: Remember "Hydro = Habitat of water, so Hardly any roots." If an option talks about a big root system or water conservation (thick cuticle, reduced leaves), it belongs to xerophytes, not hydrophytes.