Plant Adaptations to Control Water Loss

Plant Adaptations to Control Water Loss

Xerophytes (Desert Plants)

Xerophytes are adapted to survive in dry conditions with limited water:

Structural adaptations:

• Thick waxy cuticle: Waterproof barrier reducing evaporation
• Sunken stomata: Protected in pits, trapping humid air
• Reduced leaves/spines: Minimal surface area for water loss
• Rolled leaves: Creates humid microclimate (marram grass)
• Hairy leaves: Trap moisture, reduce air movement
• Succulent stems: Store water (cacti)

Physiological adaptations:

• CAM photosynthesis: Stomata open at night, closed during day
• Deep roots: Access groundwater
• Reduced stomatal density: Fewer stomata per unit area

Hydrophytes (Water Plants)

Hydrophytes have opposite adaptations for aquatic life:

• Thin/no cuticle: No need for waterproofing
• Many stomata on upper surface: Maximum gas exchange
• Large air spaces: Buoyancy and gas storage
• Flexible stems: Bend with water currents
• Large surface area: Maximum absorption

Case Study: Marram Grass

Marram grass (beach grass) shows multiple xerophytic features:

1. Rolled leaves: Curl inward in dry conditions
2. Sunken stomata: Located in grooves on inner surface
3. Hairs in grooves: Trap humid air near stomata
4. Thick cuticle: Reduces cuticular transpiration
5. Result: Can survive on sand dunes with minimal water