Pigment changes - WHY?

[Geeta Bharathan]

Martin Witchard (Cat) (mwitchar at metz.une.edu.au) wrote:
: When I look at a flower bud as it opens I can get a general idea of the 
: colour of the final flower. 
: 
: In some cases though the flower ends up being considerably lighter/paler 
: once opened or considerably stronger/more intense once opened.
: 
: I'd like to know WHAT 'pigments' are present and WHAT is happening to 
: them.  In the pink rose are the 'pigments' photodegraded? Is the same 
: occurring in the red rose, and if so, why doesn't it become white? Is it 
: possible that the Geum 'pigment' actually intensifies with 
: photostimulation?
: 
: Answers please if you have them to offer (a good reference would also be 
: appreciated!) :)
: 

Look at a paper by Martha Weiss that came out in American Journal of
Botany, sometime in 1993 or '94. It was an evolutionary perspective on
colour change in a very wide range of angiosperms. She had some
information on underlying mechanisms in some taxa. Sorry I don't have
details.


--Geeta Bharathan