What adaptations reduce transpiration in desert plants?

Desert plants reduce transpiration through adaptations such as thick cuticles, reduced leaf size, and stomatal closure.

Desert plants, also known as xerophytes, have evolved a range of adaptations to survive in arid conditions where water is scarce. One of the key adaptations is the development of a thick cuticle. The cuticle is a waxy layer that covers the surface of the leaves and stems. This layer is impermeable to water, thus reducing the amount of water lost through transpiration. The thicker the cuticle, the less water is lost.

Another adaptation is the reduction in leaf size. Smaller leaves have less surface area exposed to the air, which reduces the amount of water lost through transpiration. Some desert plants, such as cacti, have taken this to the extreme and have completely eliminated leaves. Instead, they carry out photosynthesis in their stems, which are modified to store water and are covered with a thick cuticle.

Stomatal closure is another important adaptation. Stomata are tiny openings on the surface of leaves that allow for gas exchange. However, they also represent a major route for water loss. Desert plants have evolved the ability to close their stomata during the hottest parts of the day when evaporation rates are highest, thus reducing water loss. Some desert plants also have their stomata sunken into the leaf surface or located on the underside of the leaves, which provides additional protection against water loss.

Finally, many desert plants have developed extensive root systems that can reach deep into the soil to access water. Some have taproots that can penetrate several metres into the ground, while others have wide-spreading lateral roots that can absorb water from a large area. These root adaptations not only help the plants access water, but also anchor them in the loose desert soil.