In reading on various sites, some said "orchid X" is typically terrestrial but in rainforest conditions may be epiphytic. This seems to be the exception, not the norm. A few were listed as strictly terrestrial and some were strictly epiphytes. The literature was fairly specific about which ones could grow under either situation.
I did notice that Janet's link to The Orchid Source has an ATP member posting in that link.
@Ursula may be able to help here as from what I have noted, she has a fair amount of experience with orchids.
This is a pic of Aspidogyne fimbrillaris ,a terrestrial
https://www.flickr.com/photos/...
