About Lesson
Xerophytes
These are plants that grow in deserts.
Deserts have low rainfall, very high day temperatures, low night temperatures, low humidity and strong winds.
Cactus
Adaptations of Xerophytes to their habitats
- Some have folded leaves to reduce surface area for transpiration;
- Some have needle-like leaves to reduce surface area for transpiration;
- Some have leaves modified to spines or scales to reduce surface area for transpiration;
- Some have fewer leaves to reduce surface area for transpiration;
- Some (deciduous) shed leaves during drought to reduce surface area for water loss.
- Others have hairy leaves; the hairs trap moisture reducing saturation deficit to reduce water loss through transpiration.
- Some have few stomata on the upper surface of the leaf.
- Some have reversed stomatal rhythm (close stomata during the day and open at night) to reduce water loss.
- Small sized stomata; usually located on the lower epidermis; to reduce transpiration.
- Some have sunken stomata; that trap moisture in the sunken pits; lowering saturation deficit; hence reduced transpiration rate.
- Some have thick waxy cuticle to reduce transpiration e.g. sisal.
- Some have long tap root system to absorb water from lower layers of the soil.
- Others have superficial roots that grow horizontally to absorb surface water after light showers.
- Some have succulent stems and leaves with large parenchyma cells to store water e.g. cactus, Bryophyllum
- Some have a very short life cycle to evade drought, hence survive as seeds or as underground perennating organs e.g. corms and bulbs.