FLOWERING STEM 



SCALE 



VEGETATIVE STEM 



tel 



I 



2.0 



2.9 



2.0 



1.0 



2.0 



! 



Fig. 40. The difference in polarity of auxin transport in the stems and roots of 

 coleus, showing a polar gradient from apex to base and the difference in polar 

 gradients between flowering and vegetative stems. The arrows represent the amount 

 of auxin transported in each direction through 7 mm. sections of stems or roots 

 taken from different regions of the plant (Leopold and Guernsey, 1953). 



82 



