Plant adaptations Flashcards
What are xerophytes?
Plants that adapted in dry habitats with low water availability.
E.g: maram grass, cacti
How do xerophytes conserve water?
Thick waxy cutile
Sunken stomata - somata in pits to reduce air movement
~~> produces humid air = low transpiration
Reduced number of stomata
Reduced leaf area = minimise SA:V
Hairy leaves = microclimate of humidity
Curled leaves = confines stomata to same humid environment
Succulents = stores water in parenchyma tissues.
Leaf loss = lose leaves when water not available
What are root adaptations to attain as much water as possible?
Long trap roots = penetrate several meters to access water below surface.
Widespread shallow roots = large SA:V
Marram grass = horizontal roots = extensive network = enable sand to hold more water
How to some plants avoid lack of water availability?
Become dormant
Die but leave seeds behind to germinate.
Storage organs = bulbs/tubers/corms.
Some withstand dehydration
What are hydrophytes?
Plants that live in water/permanently saturated soil
E.g: lilies, water cress
Adaptations of hydrophytes:
Very thin/no waxy cuticle
Many open stomata on upper surfaces -> in contact with air
Reduced structure to plant = water supporting plant
Wide, flat leaves = capture as much light as possible
Small roots = less need for root uptake
Large SA of stems + roots under water = maximises area for photosynthesis + for O2 to diffuse
Air sacs = to allow leaf to float
Aerenchyma
Why is the aerenchyma necessary?
Specialised parenchyma (packing) tissues.
Large air spaces:
~ Makes leaves + stem more bouyant
~Forming low-resistance internal pathway for movement of substances (O2) to tissues below water.
~> helps with anoxic conditions
Why can aerenchyma be bad?
Methane produced by rice plant = greenhouse effect.
Solution = waterlogging
