This picture is of a couple of pineapples, which are fruits that grows on CAM plants. CAM stands for Crassulacean Acid Metabolism. CAM plants often live in very dry climates and thus have to find a way to retain water better. As an evolutionary adaption, CAM plants open their stomata only at night to let in the CO2 that they need. The CO2 that comes in is turned into a four-carbon compound that is stored to be used later in the Calvin Cycle during the day. This process allows the CAM plant to still perform photosynthesis during the day but it no longer has to lose as much water because its stomata are closed when it is hot during the day.