Crassulacean Acid Metabolism

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Crassulacean Acid Metabolism

botany

Also known as: CAM, crassulacean metabolism

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June 25, 2026

Quick Summary

Crassulacean Acid Metabolism (CAM) is a specialized photosynthetic pathway found in over 20,000 plant species, including succulents, orchids, and cacti. This pathway allows plants to conserve water by opening their stomata at night to absorb carbon dioxide (CO2) and storing it as malate in their cell vacuoles. During the day, the stomata close to prevent water loss, and the stored CO2 is released and used in the Calvin-Benson cycle for photosynthesis. This temporal separation of CO2 uptake and fixation is a key adaptation for plants in arid environments, enabling them to thrive with significantly less water than C3 and C4 plants.1

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agave
Physical description
…a photosynthetic pathway known as crassulacean acid metabolism (CAM), in which carbon dioxide is fixed at night to limit the amount of water lost from the leaf stomata.
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…a photosynthetic pathway known as crassulacean acid metabolism (CAM), in which carbon dioxide is fixed at night to limit the amount of water lost from the leaf stomata.
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Crassulaceae
Physical description
…been named after the family—Crassulacean Acid Metabolism (CAM). Special hairs, aerial roots, and surface cells may enable some species to absorb water directly from the air. Members of the genus Kalanchoe produce clonal plantlets on the indentations of the leaf margins. Flowers in the family are bisexual, with the…
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…been named after the family—Crassulacean Acid Metabolism (CAM). Special hairs, aerial roots, and surface cells may enable some species to absorb water directly from the air. Members of the genus Kalanchoe produce clonal plantlets on the indentations of the leaf margins. Flowers in the family are bisexual, with the…
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plant
Specific variations in photosynthesis
This process is called crassulacean acid metabolism (hence CAM plants), after a family of succulent plants (Crassulaceae).
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This process is called crassulacean acid metabolism (hence CAM plants), after a family of succulent plants (Crassulaceae).
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Saxifragales
Major families
…been named after the family—Crassulacean Acid Metabolism (CAM). Special hairs, aerial roots, and surface cells may enable some species to absorb water directly from the air. Members of the genus Kalanchoe produce plantlets on the indentations of the leaf margins. Flowers in the family are bisexual, with the perianth…
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…been named after the family—Crassulacean Acid Metabolism (CAM). Special hairs, aerial roots, and surface cells may enable some species to absorb water directly from the air. Members of the genus Kalanchoe produce plantlets on the indentations of the leaf margins. Flowers in the family are bisexual, with the perianth…
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stomate
…plants that photosynthesize with the CAM carbon fixation pathway, such as bromeliads and members of the family Crassulaceae, stomata are opened at night to reduce water loss from evapotranspiration.
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…plants that photosynthesize with the CAM carbon fixation pathway, such as bromeliads and members of the family Crassulaceae, stomata are opened at night to reduce water loss from evapotranspiration.
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succulent
…CO₂ fixation and photosynthesis called crassulacean acid metabolism.
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…CO₂ fixation and photosynthesis called crassulacean acid metabolism.
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transpiration
…evolved alternative photosynthetic pathways, like crassulacean acid metabolism (CAM), to minimize transpiration losses. These plants, including many succulents, open their stomata at night to take in carbon dioxide and close them during the day when conditions are commonly hot and dry.
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…evolved alternative photosynthetic pathways, like crassulacean acid metabolism (CAM), to minimize transpiration losses. These plants, including many succulents, open their stomata at night to take in carbon dioxide and close them during the day when conditions are commonly hot and dry.
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