CAM photosynthesis
/kæm ˌfoʊtoʊˈsɪnθəsɪs/
Definition
Cam photosynthesis is a water-saving photosynthetic pathway used by many succulents, cacti, orchids, and bromeliads. In this process, stomata open at night to take in carbon dioxide, which is stored as organic acids. During the day, the stomata stay mostly closed, and the stored carbon dioxide is released for sugar production in sunlight. This separates gas uptake from daytime photosynthesis and helps plants reduce water loss in dry conditions.
Biological Role
- Water-saving strategy: Cam photosynthesis lets plants keep stomata, the tiny leaf pores, closed during the hottest part of the day. That sharply reduces water loss in dry, sunny, or salty habitats.
- Common in succulents and epiphytes: It is widespread in cacti, many Agave species, many orchids, and bromeliads. This helps explain why these plants can live on rock, bark, or shallow, fast-drying soils.
- Tradeoff with growth rate: Because carbon uptake is limited to nighttime storage and daytime release, plants using cam photosynthesis often grow more slowly than many plants with C3 photosynthesis when water is plentiful.
- Can shift with conditions: Some species show facultative behavior, meaning they can increase or reduce cam photosynthesis depending on drought or other stress. This flexibility helps them balance water conservation with growth.
Related Terms
Photosynthesis
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Stoma
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Transpiration
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Carbon dioxide
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Chlorophyll
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Chloroplast
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Succulent
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Xerophyte
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