plant adaptations to water availability

• what are the two types of plants adapted to water availability?

  • xerophytes- adapted to conserve water
  • hydrophytes- adapted to water-rich conditions
• state some of the adaptations xerophytes have

  • thick waxy cuticle to reduce water loss by transpiration
  • sunken stomata- limits air movement and creates an environment of humid air
  • less stomata- to limit water loss
  • less leaves- less SA:V, reducing rate of water loss
  • hairy leaves- create a microclimate of still, humid air
  • water stores in parenchyma tissue
  • root adaptations- grow deep into the ground to get as much water as possible
  • leaf loss
  • curled leaves- confines stomata into a microclimate of still humid air reducing water vapor potential gradient and limiting transpiration
• state some adaptations that hydrophytes have

  • very thin or no waxy cuticle- water loss by transpiration isn't an issue
  • many open stomata on upper surfaces- maximises gaseous exchange
  • reduced supporting structures- plants supported by water so they don't have many structural features providing support, conserves energy
  • wide, flat leaves- which spread across the water to capture as much light as possible
  • small roots- water can diffuse into stem and leaves, less need for root uptake
  • large SA of stem and roots underwater- maximises area for photosynthesis and for oxygen to diffuse in
  • air sacs- buoyancy
  • aerenchyma- specialised parenchyma in the leaves/roots, air spaces. For buoyancy and ease of O2 transmission through low resistance pathways to oxygen depleted (anoxic) areas that parts of the plant are in
• how are aerenchyma formed?

  through apoptosis
• what does water-logged mean?

  too much water- not enough oxygen is available to plants so limited respiration
• what are hydrophytes?

  plants that live in water-rich conditions or saturated soil
• what are xerophytes?

  plants that live in areas which are water sparse- not much water available
• state 2 examples of xerophytes

  cacti and marram grass
• state an example of a hydrophyte

  water lillies