I don't have Marsilea quadrifolia , but from what I've read it's transition from emersed to submersed isn't the prettiest. It is supposed to make a nice carpet. Be sure to post pics. I've been debating on whether or not I want to rescape my bowl and the layout you're doing is similar to something I had in my mind. I just haven't been able to figure out what plants would carpet well in a bowl.
My plan on the Marsilea Quadrifolia was to plant a half dozen nodes around and wait for them to get a nice network of runners going then pinch off the tops before I fill the tank. Those plans were shot to hell because the nursery I was going to buy them from tossed them away due to an ant infestation (which is why they were priced so low when I looked a few weeks back)
We do have an a store that has Marsilea minutea that has been submersed grown, but I'm worried it will come uprooted too easily when I'm doing the tri-weekly water changes the first month.
Also, instead of X-mas Moss, I've gone with flame moss since I got a nice size portion for free on the condition I grow it out and return some to the LFS in the future. It has already attached pretty well to my substrate so I'm pleased with that.
I also purchased several small seiyru stones, however I have less room to work with than I planned so I've just picked the most interesting one and placed it in a "corner" of the bowl that wasn't as interesting as the rest.
My favorite part of such tiny bowls is that you have to take great care to make sure it is interesting from every angle you look at it.
Any suggestions on other plants to use? I'm looking for something that doesn't get taller than 3 inches, does well in low light and will feed primarily from the water column, and will help distort the scale a little.
i was thinking Downoii, but the substrate isn't really deep enough for it to thrive.
My other thought was microsword, but then I'm looking at a LONG dry start and potentially needing to dose in the future.
I can also get baby tears and dwarf baby tears pretty easy, but I don't think they look that nice in small tanks unless used for full carpet.
I really want this beautiful piece of manzanita to be the centerpiece otherwise I guess I could get a few rhizomes of anubias nana petite. Or a nice lotus.
I'd appreciate any help or ideas. I'll have a friend take pictures of my work bowl next week and upload it.