specially adapted plants

• what are mesophytes?

  plants that are able to take up sufficient water to replace transpiration (most plants)
• what are hydrophytes?

  plants that live either partially or completely submerged in water - problems with oxygen uptake
• what are xerophytes?

  plants that live in areas where water lost by transpiration is greater than taken up by roots
• Xerophytes

  • Adapted to prevent water loss
• adaptations of Marram grass(xerophytes)

  • Stomata sunk in pits, sheltered from wind --> slows transpiration
  • Layers of hairs on epidermis trap moist air around stomata, reduces water potential gradient, slows transpiration
  • In hot/windy conditions, rolls leaves to trap moist air, slows transpiration and reduces exposed surface area, protects stomata from wind
• adaptations of Marram grass and cacti(xerophytes)

  • Thick, waxy layer on epidermis - reduces evaporation as it is waterproof
• adaptations of Cacti(xerophytes)

  • Have spines instead of leaves to reduce surface area for water loss
  • Close stomata at hottest times of day when transpiration rates are highest
• adaptations of Hydrophytes for oxygen uptake

  • Air spaces in the tissues help plants to float
  • Air spaces can act as a store of oxygen for use in respiration
  • Water lilies have large air spaces in their leaves, allowing them to float on the water surface, increasing the amount of light they receive
  • Air spaces in roots and stems allow oxygen to move from floating leaves down to underwater parts
• adaptations of Hydrophytesfor oxygen uptake

  • Stomata are usually only present on the upper surface of floating leaves
  • Helps to maximise gas exchange
• adaptations of Hydrophytesfor oxygen uptake

  • They often have flexible leaves and stems
  • These plants are supported by the water around them so they don't need rigid stems for support
  • Flexibility helps to prevent damage by water currents