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growing R. wallichii


A few weeks ago I came across some Rotala wallichii at my favorite local
plant shop.  I bought a couple bunches and promptly stuck them into my
nursery tank to find out how they would do.  The stems were rootless and
seemed unusually stiff compared to the stems of their close cousin - R.
rotundifolia - in another of my tanks.

The plants didn't do well.  After putting out a little bit of new growth
they stopped growing entirely and the initially reddish growth at the tip
of the plant turned green and the leaves fell off the lower half of the

Most plants grow pretty well in my nursery tank, but it's lighting is a
little dim.  After a couple weeks I started thinking that the plants might
need more light so I pulled one group of three stems and moved them to
another tank with brighter light.  The stems had developed almost no roots
in the time they were in the nursery tank.

In the brighter tank I started seeing bubbles collecting in the R.
wallichii needles, but with a fine-leafed plant like this it's hard to say
whether the bubbles were produced by the plant or were produced by a
neighboring plant and merely got caught in the leaves.  Aside from the
afternoon bubbles there weren't any changes for the better; more leaves
dropped and the color went from green to brown.  Then, after a week or so
a new bud appeared at the base of one stem and a healthy-looking,
beautifully colored new stem began to grow.  After that I moved all of the
other stems into the same tank.  They too had little or no new root growth
and oddly stiff stems.

I saw very similar behavior in some Heteranthera zosterifolia (actually
sold as Didiplis diandra) and lysimachia numularia that I bought last
spring.  In both cases the plants grew briefly then stopped, existing
leaves gradually fell off, roots failed to develop and the stems became
stiff and twisted.

I threw most of the stems away, but kept a couple around to the bitter
end, just to see what would happen.  After a couple months both plants
produced new buds and set about normal rapid growth. I threw away the H.
zosterifolia (which I already had plenty of)  once it became clear that it
wasn't Didiplis diandra, but I kept the Lysimachia and now have a small
stand of it that I've propogated from a couple stems.

Last summer Stephane Andre posted the idea that some nurserys grow emersed
plants under conditions that are so dry that they don't adapt quickly to
submersed growth.  I took that as a good explanation for my problem with
the H. zosterifolia (which didn't look like my submersed H. zosterifolia
when I bought it) and the L. nummularia, which I think is naturally an
emergent plant.

But can that be true of the R. wallichii as well?  Has anyone else had
this problem and found a way around it?  Stephane suggest setting up a
little mini-greenhouse somehow and slowly adapting plants through very
humid conditions to submersed conditions.  Has anyone tried that?

I guess the upshot of the story might be, if your newly-purchased stem
plants stop growing, go into apparent dormancy and seem to be dying, you
don't necessarily need to throw them out.  Wait patiently and you might
eventually get the plant you wanted.

Roger Miller