Subject: Capillary action in flowers with hot water?

I am doing an experiment demonstrating capillary action using white carnations
and food dye.  I am using room temperature 80degree F. water in one vase with
food color and another vase with same amount of water and food dye, but 150 
degree F. water.  Color change consistently occurs in the room temp vase 
flower,but never with the hot water.  What is the name of the principle it must
be related to heat stress that deals with why the color change does not occur
with the hot water?  Thank you for your help.  

Re: Capillary action in flowers with hot water?