I think lowii are considered mainly epiphytic. And, by the way, with the concept of epiphytic we have to tread with care: Braem describes a lot of Paph-species, that other describe as litophytically or terrestially growing, as humus-epiphytes, i.e. they might grow on the ground, f.ex. at the foot of large trees, or on rocky ground, but in both cases only where old leaves and other like organic material have collected, in cracks in the rocks, inbetween the roots of the tree, etc. - and with the milieue this humus-material generates being a prerequisite for them growing there. I think he has quite a point.
A point that also has some implications for culture, as the presence of the humus might affect f.ex. the overall PH value of the mikro milieue, i.e. one can't 110% deduct that a plant growing on calceolous cliffs, but as a humus-epiphyte, needs a growth medium veering on the side of alkaline. If my memory doesn't elude me completely, I think, Averyanov et al. did analyse the rainwater running from the spots, where P. henryanum grew, and found it just very slightly acidic, even though the cliffs themselves, on which the plants were growing, were limestone! Quite an interesting observation.
