CAM is an acronym for crassulacean acid metabolism, a photosynthetic process used by plants that live in dry and/or arid environments. Plants in arid climates can lose a lot of moisture if their stoma are open during the day to let in carbon dioxide. CAM plants leave their stoma closed during the day and open them at night instead. However, because there is no sunlight at night for photosynthesis, CAM plants need a method to hold onto the carbon dioxide until the day time. The carbon dioxide that CAM plants take in during the night is converted into a four-carbon sugar called malate for storage. When day light returns, the carbon dioxide is released from the malate to be used in photosynthesis.

CAM plants, also called succulents, must be efficient at storing water because of the dry and arid climates they live in. The term crassulacean comes from the Latin word crassus which means “thick.” Some examples of the over 16,000 species of CAM plants on Earth are cacti, sedum, jade, orchids and agave. Succulent plants like the cactus are full of moisture and have thick skins and a waxy coating to reduce evaporation. Succulents can attract animals because they are a concentrated source of water and moisture. To defend against this, many succulents have sharp spines (which are actually modified leaves) or a “hairy” coating of fine needles to deter predators.

Cactus (Opuntia phaeacantha) flower
The image above shows the tulip prickly pear cactus Opuntia phaeacantha which is a CAM plant that has thick skin and a waxy coating to help prevent moisture loss. The needles help to deter predators.


  • Crassulacean Acid Metabolism. (n.d.). In Wikipedia. Retrieved August 7, 2017 from