Do you have a pic of one? I just pulled a bunch of some species of fern out of my bicolors viv that must have came in with the corkbark. It produces runners and it is everywhere in the tank."Weeding" the fern out and the ficus pumila is about a bimonthly thing in that viv.
I have some orchids in there that have been doing good so I don't like having the other plants shading them too much.BTW,the viv has been set up for just about 2 years.
I've been pretty insensitive to mine. I've kept it in low light, high light, let it go dry and also kept it fairly wet, and the plant seemed to take it in stride. It doesn't need as much light as some other terrarium plants, so I like to put it in places accordingly.