Adaptations to reduce water loss

• What is a mesophyte?

  Plants that have evolved in conditions of adequate water supply
• How are mesophytes adapted to reduce water loss?

  -water loss is readily replaced by uptake from soil

  -if water loss is too great, plant wilts and leaves droop

  -stomata close and leaf surface area for absorbing light is reduced, so photosynthesis becomes less efficient

  -stomata close at night
• What are xerophytes?

  Plants that have evolved where water is scarce
• How are xerophytes adapted for water loss?

  -leaves roll with adaxial surface inwards (reduces leaf area exposed to air, so reduces transpiration)

  -humid air gets trapped in pits outside stomata (reduces water potential gradient between inside and outside of leaf, so rate of diffusion of water out of the stomata decreases)

  -hairs trap water vapour and reduce water potential gradient between inside and outside the leaf

  -waxy cuticle is waterproof and so reduces water loss
• What are hydrophytes?

  Plants that have evolved traits allowing them to live in open water
• How are hydrophytes adapted to reduce water loss?

  -little/no lignified support tissues as water is a supportive medium

  -xylem is poorly developed as it is surrounded by water, so little need for transport tissue

  -leaves have little/no cuticle, no need to reduce water loss