The pincushion cactus shown above is an example of a CAM plant. Similar to the C4 plant, a CAM plant has also adapted to hot and dry weather, however CAM plants are adapted to the very dry climates. A CAM plant will only open its stomata at night, when it is colder, and admits an abundance of CO2. This CO2 is converted to a 4 carbon molecule, as in a C4 plant, and then stored in the plant. During the day, the CAM plant closes its stomata and allows the stored 4 carbon molecule to begin the Calvin cycle, operating photosynthesis with a closed stomata.