Xerophytes and hydrophytes

Overview

Advantage of a thickened cuticle in a xerophyte, how sunken stomata reduce the rate of water loss and succulent tissue.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Define a xerophyte.

   Model answer

   A xerophyte is a plant structurally adapted to survive in a habitat where water is in short supply.

2. 2

   Define a hydrophyte.

   Model answer

   A hydrophyte is a plant adapted to live wholly or partly submerged in water.

3. 3

   Explain how rolling or curling the leaf reduces water loss in a xerophyte.

   Model answer

   Curling encloses the stomata inside a chamber of still air, which becomes saturated with vapour so the diffusion gradient out of the leaf collapses.

4. 4

   How does a reduced leaf surface area help a xerophyte conserve water?

   Model answer

   A smaller surface carries fewer stomata and exposes less area for evaporation, so the total water lost is reduced.

5. 5

   Explain the advantage of a thickened cuticle in a xerophyte.

   Model answer

   A thicker waxy layer is a more effective waterproof barrier, so water loss through the leaf surface is minimised.

6. 6

   How do hairs on the leaf surface reduce transpiration?

   Model answer

   The hairs trap a layer of still humid air against the surface, which reduces the water potential gradient between the leaf and the atmosphere.

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