TRANSPORT PROCESSES IN THE SOIL-PLANT SYSTEM 



713 



leaf surface. It may be that the function of epidermal hairs is to de- 

 crease the rate of air movement across the leaf surface and thus in- 

 crease the resistance of the flow path, but it is also possible that corn 

 epidermal hairs, being rather far apart, serve instead to create turbu- 

 lence in the air at low wind speeds and thereby promote gas exchange. 

 The increase in transpiration that results from wind movement ( Figure 

 14 ) is attributed to the removal of laminar air layers at the leaf surface. 



OsIN STILL AIR 

 • «IN WIND 



5 10 15 20 



STOMATAL APERTURE INm'» 



Figure 14. The effects ot stomatal aperture and wind on transpiration. 

 (From Bange, 1953.) 



