Chapter 9.5 Adaptations For Xerophytes And Hydrophytes Flashcards
Basic adaptsions of leaf to reduce water loss
What are xerophytes vs hydrophytes
- stomata underside = reduced evaporation
- sacy curicle = reduced water loss
Xero = plants adpated to dry habitats vs hydro plants adapted to high water
General adapataions of xerophytes
Structure
- waxy cuticle
- sunken stomata
- hairs on plant
- reduced leaf and reduced lead surface area
- SUCCULENTS that have specialised parenchyma
- losing leaves
Roots
- deep and shallow roots for max rain
- specialised vertical stems rhizomes horizontal that make network to adapt to environemnt
Some can avoid problem
How xerophytes structure help reduce water loss?
- waxy cuticle : as 10% water loss through here, an impermable thick minimises if
- sunken stomata in pits : still microclimate dry air humid reduce wind conc gradeint
- reduced stomata = reduce water loss
- reduce leave SA = thin needles, less SA = less water loss
- hairy leaves / microhairs in sunken pit = still microclimate
- curled leaves = still microclimate
- succulent = speilaised parenchyma stores water in plentiful supply and use when not
How xerophytes root adaptations help
Deep and shallow roots = can catch rainwater before evaporate
Rhixomes create horixontal mat that stops sand from losing water + adapt to changing envirokent
Avoiding the problem in xerophytes?
- shed leaves = stop transpiration, and stems become green
- dormant / die and leave seeds behind to grow again
- survive as storage organs
- withstand complete dehyrdation and recoger
Adaptaions SPECIFICALLY IN MARRAM GRASS (5 ish)
- Sunken pits stomata in with microhairs in these pits too
- curled leaves = microclimate + LESS SA
- specialised horizontal mat of stems called rhizomes + long vertical roots for best of both world
- THICK WAXY CUTICLE TOO!
Adaptations SPECIFICALLY FOR CACTI
- thick waxy curicle on epidermis
- spines instead of leaves = less leaf SA thus water loss
- cacti close stomata at hottes part of day when transpiration would be highest
- also sunken stomata
- act as SUCCULENTS HAVE SPECIALISED PARENCHYMA TISSUE TO STORE WATER IN PLENTIFUL SUPPLY
- deep roots + shallow
What is hydrophytes situation !
Sumberged in water, dont need more, need to float so can photodythesise and need oxygen as lack of it underwater
Adaptations of hydrophytes
- thin cuticle + no waxy cuticle (dont need to stop water loss)
- always keep stomata open AND on upper surface (to maximise gas exchange as no threat of water loss) = === GUARD CELLS INACTIVE
- reduced structure = supported by water so dont need advanced xylem etc, just need flexible . This helps in firming currents too
- wide flat leaves to capture as much SUn light as possible
- aerenchyma = specialised parenchyma which has large air spaces created by apoptosis thst fause it to float snd offer a low resistance pathway for tissues under water for oxygen which hekod these cope woth anoxic (without oxygen) conditions in mud by jus transporting oxygen there
Roots
- small roots - water can diffuse directly inti stem and leaf tissue so less need for roots and xylem
What do aerenchyma do
aerenchyma = specialised parenchyma which has large air spaces created by apoptosis thst fause it to float snd offer a low resistance pathway for tissues under water for oxygen which hekod these cope woth anoxic (without oxygen) conditions in mud by jus transporting oxygen there
R
Again what adaptaions for water lillies (5-6)
- wide surface area on leaves
- stomate on upper side and permantely open thus guard cell inactive
- aerenchyma specialised parenchyma with apoptosis air spaces to float + provide low resistance pathway of oxygen to tissue under water facing anoxic conditions such as in mud
- small roots due to water diffusiing directly into stem etc
- lack of structure = supported by water
- no cuticle
What if compltely submerged
Grow roots outwards to allow air in
Methane aerenchyma
Methane produced in rice alsonhave low resistance pathway to escape due to aerenchyma- not good for global warming
