e) Adaptations of plants to the availability of water in their environment

Name some xerophytes

Cacti

Marram grass

Name a hydrophyte

Water lilies

Xerophyte adaptations to reduce water loss:

• Rolled leaves

• Hairy leaves

• Sunken stomata

• Needle like leaves

• Dense spongy mesophyll layer

• Less stomata

• Thick waxy cuticle

• Long deep root systems

Xerophyte adaptations - Rolled leaves

• Reduces surface area for evaporation

• Traps a layer of water vapour, creating a higher water potential outside the stomata, reducing the water vapour potential gradient, reducing evaporation of water from the leaves

Xerophyte adaptations -Hairy leaves

• Traps a layer of water vapour, creating a higher water potential outside the stomata, reducing the water vapour potential gradient, reducing evaporation of water from the leaves

Xerophyte adaptations -Sunken stomata

Traps a layer of water vapour (it isn’t taken away by the wind as easily), creating a higher water potential outside the stomata, reducing the water vapour potential gradient, reducing evaporation of water from the leaves

Xerophyte adaptations -Needle like leaves

Reduces the surface area of the leaf, therefore less evaporation of water vapour

Xerophyte adaptations -Dense spongy mesophyll layer

Smaller surface area for evaporation

Xerophyte adaptations -Less stomata

Less stomata which are closed in the day

Most of the stomata will be found on the lower surfaces of the leaves to reduce evaporation

Xerophyte adaptations -Thick waxy cuticle

Waterproof, prevents water leaving through evaporation

Xerophyte adaptations -Long deep root systems

Long deep roots to take up water

There are also a high solution concentration in root hair cells to draw more water in via osmosis

Hydrophyte adaptations

• Aerenchyma

• Large leaves

• Pneumatophore

• Lots of stomata

• Thin waxy cuticle

• Short root system

Hydrophyte adaptations - Aerenchyma

Allows buoyancy

Hydrophyte adaptations - Large leaves

Allows large surface area for leaves to increase the rate of photosynthesis

Hydrophyte adaptations - Pneumatophores

Roots that grow out of the water to aid with gas exchange

Increases the rate of photosynthesi

Hydrophyte adaptations - Lots of stomata

• Open most of the time

• Found on the upper surfaces of the leaves to increase gas exchange

Hydrophyte adaptations - Thin waxy cuticle

No need for a thick waxy cuticle as water loss doesn’t need to be prevented

Hydrophyte adaptations - Short root system

Prevents damage by currents

The plants can meet its requirements for water because it lives in water.