Question

1) a) Describe the adaptations xerophytes and halophytes have to their environments. Which adaptations are common to both?

b) What are the problems associated with high or low temperatures and what are the adaptations/acclimations that plants have to these conditions?

Answer 1

Adaptations of xerophytes include small leaves, reduced number of stomata, stomata in pits, thickened waxy cuticle, deeper roots, wide spread shallow roots, curled leaves, hair on epidermis. Adaptations of halophytes include high osmotic pressure, succulence in leaves and stems for storage of water and mucilage, scotoactive stomata, secrete lime/salts by salt or chalk glands.

Both the xerophytes and halophytes adaptations occur to minimise water loss. Most of the xerophytes and halophytes have succulent leaves and stem.

Xerophytes will have high rates of transpiration due to the high temperatures, and low rates of transpiration due to low temperature. Plants with CAM physiology open their stomata at night, reducing water loss via evaporation. For halophytes, hypersalinity often co-occurs with extreme temperature conditions, both hot and cold. Halophytes use many different strategies to survive under extreme conditions. Seeds can germinate over different time periods when conditions are more favourable otherwise the seeds can be in dormant stage in unfavourable conditions.