CAM plants do not have specialized bundle sheath cells,and thus they open their stomata during during the cool desert nights to minimize water loss. During the night, PEP,carboxylase fixes the Carbon Dioxide and accumulates large quantities of malic acid in the vacuoles of the mesophyll cells.
During the night, the plants close their stomata to retain water. Malic acid gives up the Carbon Dioxide is fixed by the RuBP and incoporated into the Calvin's cycle. Carbon Dioxide concentration remains high in the leaf during the day due to the closed stomata thus preventing photorespiration.
