Subject: Why should one put a penny in the water with fresh cut tulips?

I work in a flower shop and often dispense advice on the care for fresh-cut 
flowers.  I've heard that one should place a penny in the water with fresh-cut 
tulips.  Something about the copper in the water and the fresh-cut stems of the 
tulips having a chemical reaction.  I would really appreciate the answer if you 
have the time. Thank you.

P.S.  I've tried to find the answer to this question all over the Web with no 
luck.  Oncve again, thank you !!!! :) 

Re: Why should one put a penny in the water with fresh cut tulips?