Cacti have evolved to store water in their specialized tissues, called parenchyma, which allows them to survive long periods without rainfall. The thick, succulent stems and leaves of cacti act as reservoirs, enabling them to photosynthesize and produce food even during drought.
Reduced leaf surface area:
To minimize water loss through transpiration (the process of water evaporation from leaves), cacti have reduced their leaf surface area. Instead, they have spines, which help protect them from predators and further reduce water loss.
Thick, waxy cuticles:
The outer surface of cacti is often covered with a thick cuticle, a waxy layer that helps prevent water evaporation. This waxy coating further aids in water retention.
Shallow root systems:
Cacti have shallow and widespread root systems that enable them to capture water quickly after sporadic rainfall events. These roots are adapted to absorb moisture efficiently from the soil, even during short-lived downpours.
Slow metabolism and growth rate:
Cacti generally have a slow metabolism and growth rate, requiring less water and energy to sustain themselves compared to other plants. This adaptation helps them endure harsh environments where resources are scarce.
Protection from extreme temperatures:
Cacti can withstand extreme temperatures, from scorching heat to freezing conditions, thanks to their unique physiological adaptations.
Few pests and diseases:
Cacti have few natural pests and diseases due to their unpalatable tissues, thick cuticles, and lack of vulnerable foliage, which contribute to their longevity.