It can be described in following ways :
1. Crasslacean acid metabolism (CAM) refers to a mechanism of photosynthesis that is different than already discussed C3 and C4 pathways.
2. This occurs only in succulents and other plants that normally grow in dry conditions.
3. In CAM plants C02 taken up by leaves or green stems through stomata, which remain open at night.
4. However during the day the stomata remain closed in these plants to conserve moisture.
5. The CO2 taken up in the night is fixed in the same way as in C4 plants to form malic acid, which is stored in the vacuole.
6. The malic acid thus formed during the night is used during the day as a source of CO2 for photosynthesis to proceed via the C3 pathway.
Significance : Thus CAM is a kind of adaptation that allows certain plants (for example, pineapple) to carry out photosynthesis without much loss of water.