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Definition

noun

(botany)

A plant that utilizes the Crassulacean acid metabolism (CAM) as an adaptation for arid conditions. CO₂ entering the stomata during the night is converted into organic acids, which release CO₂ for the Calvin Cycle during the day, when the stomata are closed.

Supplement

CAM plants often show xerophytic features, such as thick, reduced leaves with a low surface-area-to-volume ratio, thick cuticle, and stomata sunken into pits.

Cam plants utilize an elaborate carbon fixation pathway in a way that the stomata are open at night to permit entry of CO₂ to be fixed and stored as a four-carbon acid (i.e. malate).Then, during the day the CO₂ is released for use in the Calvin cycle. In this way, the rubisco is provided with high concentration of CO₂ while the stomata are closed during the hottest and driest part of the day to prevent the excessive loss of water. CAM plants are therefore highly adapted to arid conditions.

Examples of CAM plants include orchids, cactus, jade plant, etc.

Compare: C3 plant, C4 plant.
See also: Crassulacean acid metabolism, Calvin cycle.