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RE: Iron and red plants

Mark Fisher wrote:
> I have to wonder why some aquatic plants are red.  UV protection would be
> less important to a submersed plant than an emersed, or terrestrial plant,
> and I doubt that it has an "attractor" function.  Perhaps the red color is
> simply a "leftover" from its terrestrial origins?

Yes, I would guess that the red color of Alternanthera, which is really
a terrestrial plant that tolerates being under water, is a byproduct of
a terrestrial adaptation not as a specialized adaptation to living under
water or in a marginal (edge of the water) biotope.

Ammania grows wonderfully green when it gets above water but is a lovely
pink submersed. I asked this question a while back and never got a
satisfactory answer. I think its because some aspect of the morphology
of the plant leaf changes when under water; this must be an adaptation
to swamp life where being able to change morphology when submersed is an
important survival factor. So my guess is that the plant leaf does not
require a thick cuticle (is that the right term?) to prevent water loss
and to increase gaseous interchange underwater and therefore the
pigments in the interior structures become visible. Or perhaps, the
anthocyanin production is stimulated because other morphological changes
no longer protect the interior leaf structures from UV light.

As for Alternanthera, it looks the same above or below water and so I
don't think it is specialized to the marginal biotope such as Crypts and
others are. It just tolerates it and survives flooding to live another

Steve Pushak                              Vancouver, BC, CANADA 

Visit "Steve's Aquatic Page"      http://home.infinet.net/teban/
 for LOTS of pics, tips and links for aquatic gardening!!!