Why do many succulent plants open their stomata at night?

Many succulent plants open their stomata at night as a vital adaptation to survive in arid desert environments. By keeping their stomata closed during the hot, dry daylight hours, these plants significantly minimize water loss through transpiration.123

This behavior is a key component of a specialized photosynthetic pathway known as crassulacean acid metabolism (CAM). Because the air is cooler and more humid at night, the plants can safely open their stomata to assimilate carbon dioxide without risking excessive dehydration. Once taken in, the carbon dioxide is fixed into organic acids, such as malate, and stored in the plant's vacuoles. During the following day, the stomata remain closed, and the stored malate is broken down to release the carbon dioxide, which is then used in the Calvin-Benson cycle to produce sugars. This temporal separation of carbon fixation allows succulent plants to maintain photosynthetic productivity while thriving in conditions where water is scarce.1243