Which species can be mounted and which cannot?

[katsucats]

Every plant, period, whether it's terrestrial, non-orchid or what not, could be mounted. The medium acts to preserve moisture and nutrients. You could grow anything in hydroponic mediums without soil. So the only question is then how are you substituting the conditions that the medium provides? You'd need some way to trap moisture. Maybe a little bit of moss under it does it. Or maybe you'd need to put it by a humidifier or in a terrarium. Or maybe you live in Florida and it's naturally humid. Or your conditions are stagnant and water on surfaces take longer to evaporate. Etc.