Pruning Alternanthera reineckii
 

I have a relatively new (2 months) planted aquarium (Eclipse 12, so
not very big). My question has to do with pruning stem plants,
particularly Alt. reineckii.

I notice on my plants, of which I have about 8 stems, that there are
what appear to be roots growing from the points at which leaves branch
out from the stem. This appears all the way up the stem, not just at
one point. Now, the tops of the plants are starting to look a little
crumply and worn, and a little brown on the edges, so I presume that
pruning would be a good thing. On this, I have three questions.

First, how far back would it be prudent to cut the plant back? I think
I read somewhere that where it gets cut, two new stems should sprout,
so if I cut too close to the top, the plant will eventually get very
top heavy.

Second, do I cut the plant at a point where leaves are branching out,
or somewhere mid-stalk?

And third, can I plant the top part that I cut off or are the crumply
leaves a sign that the top is no longer healthy?

Thanks, in advance, for any advice anyone may have. Here is a link to
a picture of the "roots" I am talking about:

http://members.rogers.com/tom.otvos/...G_0044-sm.jpg.

-- tomo