Why a cactus stay green all year?

Cacti stay green all year due to several adaptations that help them conserve water and survive in arid environments:

Succulence: Cacti store water in their fleshy stems, leaves, or roots. This ability allows them to survive long periods without rainfall.

Reduced Leaves: Many cacti have evolved reduced leaves, such as spines or thorns, to minimize water loss through transpiration.

Thick Cuticle: The outer layer of cactus skin is covered with a thick cuticle that helps reduce water evaporation.

CAM (Crassulacean Acid Metabolism): In addition to photosynthesis during the day, cacti carry out CAM which involves the initial fixation of carbon dioxide at night due to open stomata, followed by photosynthetic release of the stored carbon dioxide during the day with stomatal closure to prevent water loss.

Deep Root Systems: Cacti often have deep root systems that can reach water sources far below the surface, allowing them to survive even in the driest conditions.

Together, these adaptations enable cacti to conserve water effectively, which is why they retain their green color despite living in some of the driest regions on Earth. Their specialized mechanisms to avoid water loss and store energy as water makes them well-suited to thrive in challenging arid environments.