9.5 plant adaption to water avalibilaty Flashcards
Define xerophytes and give an example
Plants with adaptations that enable them to survive in dry habitats with short water supply. Cacti, Marram Grass
How are xerophytes leaves adapted to conserve h20
Reduced Leaves - Reduces SA:V ratio, minimises transpiration water loss. E.g. thin needles in conifers
Hairy Leaves - e.g. spine of cacti, creates microclimate of humid air, reducing water vapour potential gradient. -
Curled Leaves - Confines stomata to microclimate of still humid air. e.g. Marram grass
Leaf Loss - when water isn’t available, some plants shed leaves to prevent water loss
Thick waxy cuticle
How are xerophytes stomata adapted
Sunken Stomata - stomata located in pits, reduce air movement, produces microclimate of humid air
reduces water vapour potential gradient - e.g. in cacti, marram grass,
Reduced Stomata No - reduces water loss by transpiration, but also reduces gas exchange capabilities.
What adaptions do the roots of xerophytes have
Long tap roots, grow deep into soil to access water
Widespread shallow roots
large surface area to absorb any water e.g. cacti roots grow 12-18m
Define hydrophytes and give an example
Plants adapted to survive in wet habitats, submerged or on surface of water E.g. water lillies
What issues do hydrophytes face even though they have a good water supply
Water-logging air spaces in plants, air spaces must have air
Adaptions of hydrophytes
Reduced Plant Structure - water provides buoyancy for leaves and flowers
Wide Flat Leaves - e.g. water lilly, spread across surface to capture light small roots - water diffuses directly so no need for sole water uptake via a root
Thin/No Waxy Cuticle - don’t need to conserve water as water lost by transpiration is always replaced
Air Sacs - enables leaves to float
Large Stem/Roots - for underwater plants, maximises area for photosynthesis and oxygen diffusion
Stomata are always open to allow lots of gas exchange
