nano-vivarium thoughts?

That's pretty sweet! As far as planting, I think it would look nice with a moss- and selaginella-heavy scheme with some red-leaved ludwigia down low and maybe a small fern or bromeliad as the centerpiece. As long as you have no animals there is no need for filtration.
 
Pics!
 
You could probably keep the humidity pretty cranked up in there, java fern would likely do well. Peperomia rubella may be a good choice, not sure if it would be too humid or not(I just recieved some cutting myself, have to see how it does in my tanks). You could even try some microgramma (M. nitida perhaps) ferns if you like, but those may get kinda large for the tank.
 
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