Why plants turn red

["Karen Randall" <krandall at world_std.com>]

James wrote:

>> One very important function of some of these auxiliary pigments is to act
as
a form of protection for chlorophyll molecules against the free radicals
which can be formed within the cells under intense light. Sort of like
molecular sun shades. In cases where this happens, the red or violet color
of the auxilliary pigment can visually overpower the green color of the
chlorophyll and the plant will appear red or purple (Ever see an apple that
had one side red while the other side was green? The red side was in
sunshine, the green side was in shade. The apple produced more red pigment
in the sunlit skin to protect itself from the damaging effects of too much
light. At least, that's one theory....).<<

And IMO, not a very good theory when it comes to figuring out why aquatic
plants turn red.  Most of the bright red plants that we use in the aquarium
are NOT red when grown emersed in in full sun.  Only the submersed foliage
is red.  That would make no sense if the purpose is to protect the plant
from burning in the sun.

Karen