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Re: Aquatic Plants Digest V2 #852

Subject: Re: Green light

>I enjoyed your post George... if anyone is confused please look on page 
>21 of Aquarium Plants by Barry James (or any Plant Physiology textbook). 
>Photosynthetic plants clearly absorb light in the green part of the 
>spectrum... just less efficiently than in the red or blue region. This is 
>why plants appear green. It was always explained to me that red pigment 
>in a plants photosynthetic organs is a protective measure in response to 
>strong light.

I'm not sure what relevance this has to whether (or how much) green light
plants use, but I have another (I think) interesting observation on at
least one species of red plant and light levels.  I set up a 100G tub
garden in my yard this summer.  Along with the various pond plants I threw
several aquarium plants in as well.  Since I am constantly weeding R.
macrandra out of my tanks indoors, I included some of that.  The plant is
growing well, but in very shallow water (just under the surface) and 9
hours of direct sunlight, the leaves are green with only a rosy tinge on
the edges.  The emersed leaves are very shiny, and darker green with even
less red.

I checked with another friend of mine who grows aquarium plants outdoors
during the summer, and he has had exactly the same experience with the
plant.  In both cases, the original stock was bright magenta when it was
placed outdoors.  This certainly doesn't seem like a case of the red
pigment protecting the plant from bright light.  

>On another note, many aquatic plants have the ability to double in 
>size every 2 to 4 days under optimal conditions... to see an ad boasting 
>of 6" growth after several weeks is truly hilarious... what is amazing to 
>me is that the plant actually survived that long under such obviously 
>inadequate conditions!

I think there may be some useful applications, however.  I might try it as
a growth retardant in my 2 1/2G tanks!<g>


Subject: Riccia

There is more to this Riccia business than meets the eye.  I have seen
Riccia stock directly from Amano, and in person, compared side-by-side with
our typical aquarium stock, it looks quite different.  It is a darker
green, and the individual segments are rounder instead of flattened, and
somehow "sturdier" looking.  Most importantly, if you plop a wad of it in a
tank, it sinks to the bottom.  In a well lit tank, if not tied down, it
will tend to float back toward the surface while photosynthesizing (the O2
bubbles buoy it up) but it appears to have close to neutral buoyancy on its

Like most of the other people on the list who have commented, I have had
little luck keeping our common Riccia pinned down for extended periods of
time.  I suspect that part of the reason is that I don't have the oriental
attention to detail, and tend to let it get away from me!<g>  On the other
hand, I _have_ seen it growing in lovely clumps on the bottom of both
natural and ornamental ponds.  I have even brought some of these clumps
home, and have them growing in very shallow water on my windowsills.  I
can't seem to get the same effect in the deeper water of the tanks, though.

One other tip.  When Claus Christensen was visiting, he saw me trying to
manually rid some of my Riccia of bits of Utricularia.  He told me that
Amano uses this more structured, but similarly colored plant to act as
anchoring material for his Riccia.  When I went back and looked through
close ups of some of Amano's tanks, I realized that not _all_ those bubbles
in the Riccia were O2... if you look closely, you will see that some of
them are Utricularia bladders!

Karen Randall
Aquatic Gardeners Association