Water Vapor Exchange and Stomata of CAM Plants

Gas exchange processes of plants, in particular exchange of water vapor (transpiration), is to a large extent mediated by the stomata. Transpiration can be considered a physical process depending on vapor pressure gradients between the 

The vapor pressure gradient is solely a physical property depending upon environmental factors. In contrast, the stomata with variable apertures respond to plant parameters as well. 

Provided that the magnitude of cuticular transpiration is insignificant (which is true in the majority of CAM plants), the transpiration rate is a convenient indicator of the diffusive capacity of stomata. Hence, it is reasonable to consider the properties of transpiration as observed in CAM plants in terms of stomatal movements, and vice versa. In this chapter, we will therefore mainly detail the current knowledge of stomata in CAM plants. The ecological implications of water vapor exchange of CAM plants will be discussed in detail in Chapter 6. 

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