Lesson 5 Flashcards
What are mesophytes?
• Plants that grow in temperate regions
• Grow well in drained soils and moderately dry air
Describe some behaviours of mesophytes for their survival
• Deciduous trees shed leaves in autumn to survive cold, drier conditions in winter and new ones grow in spring
• Bulbs and corms (storage organs) are produced by non-woody to survive underground during winter
• Annual plants produce seeds and die in same year, where seed survive winter and germinate during winter for better conditions
What are hydrophytes?
Water plants which are partially or completely submerged in water such as a water lily
Why is stomata on upper epidermis in hydrophytes?
• Allow gas exchange with the air above
What are large air spaces for in hydrophytes?
• Provide buoyancy for leaves and act as reservoir for oxygen and CO2
Why do hydrophytes have no waxy cuticle?
No need to reduce water loss as they live on or in water
Why do they have underdeveloped xylem?
No need to transport large quantities of water as they are aquatic
Why do they have less lignin?
Because water is already a supportive medium and lignin isn’t needed to support xylem tissue
What are xerophytes?
• Plants adapted to conditions with low water availability
• Live in dry deserts, cold regions whet soil is often frozen
• Marram grass is example
Name some adaptations of xerophytes
• Thick waxy cuticle
• Hairs
• Sunken stomata
Describe some adaptations of marram grass
• Sunken stomata in pits/hairs on surface of leaf - Water vapour trapped in pits/between hairs
• Decreases diffusion gradient between inside and outside of leaf • less water lost by transpiration
Describe some other adaptations of marram grass
• Rolled leaves - Stomata less exposed to atmosphere and water vapour trapped so diffusion gradient between inside and outside decrease. So less water lost by transpiration
• Thick waxy cuticle - Reduces water loss from epidermis
• Reduced leaf size - Less SA for transpiration to occur
Describe some adaptations of cacti
• Succulent stems to store H2O
• Leaves are spiny which reduces SA for transpiration
• Shallow-spreading/long and deep - Max water absorption
Why may xerophytes open stomata during night instead of day?
Less evaporation during night than day
