Transpiration of Water from Leaves Photosynthesis and Its Implications for Global Warming

Illustration 3.6 Transpiration of Water from Leaves. Photosynthesis and Its Implications for Global Warming 

The principal transport processes in a leaf, apart from the conveyance of nutrients, are the uptake of carbon dioxide from the air, and the release of oxygen and of water vapor to tire atmosphere. The latter process is referred to as transpiration. 

The inferior of the leaves contains the mesomorphic cells, which are arranged in either a loosely packed, spongy configuration or in the denser palisade form. The intervening spaces are taken up by intercellular air. These mesomorphic cells contain smaller cells termed chloroplasts, which in turn carry chlorophyll, the principal substance responsible for photosynthesis, i.e., the conversion of carbon dioxide into organic compmmds and oxygen. This process is addressed in greater detail in Practice Problem 3.7. 

In the present illustration we consider the transport of water vapor from the interior of the leaf through the stomatal pores into the surroxmding atmosphere. To obtain an assessment of the maximum possible moisture loss, we assume the interior of the leaf to be saturated with water vapor. 

In principle, the external resistance will depend on wind conditions, which vary with time as well as with location. Extensive studies have shown that 

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