This form of photosynthesis is a variation on the Hatch-Slack pathway or C4 pathway. In CAM plants both the C3 (Calvin Benson cycle)and the C4 pathway occur in the photosynthetic cell, but not simultaneously.
CAM is an adaptation to hot dry climates. It allows plants to open their stomata during the night to fix carbon dioxide into C4 molecules when evaporation will be minimised. These products are then stored in vacuoles of the mesophyll cells until they can be decarboxylated when the sunlight returns. Carbon dioxide is also concentrated in the cells overnight for efficient photosynthesis during the day.
Plants that have evolved crassulacean acid metabolism include the succulents of the flowering plant family Crassulaceae, and members of Bromeliaceae (such as the pineapple plant. Both families evolved this trait independently.