From what I've seen of the photos of them growing in the wild, many of them are growing on limestone that have a layer of live moss growing on them. It is constantly moist.
In the case of the Phrags, I've seen photos of the rocks they are growing on covered in lichens as well.
The roots of these lithophytes are usually hidden between rock crevices. These crevices are probably trapping a small amount of some kind of organic materials.
I've grown a few of the limestone growing orchids, and from what I've seen, they can tolerate our tap water just fine. Our tap water has a lot of dissolved minerals in them and are hard, with a pH that is likely somewhere on the order of 8.
You can try to do a Google search and see if you can pull a few pics of these orchids growing in the wild. Even better, would be if you could afford to make a trip to these countries and find a reliable tour guide to take you to these plants.
Btw, if you like something that looks like Paph delenatii, but grows on limestone hills, then Paph vietnamense also grows on limestone hills.
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Philip
Last edited by King_of_orchid_growing:); 02-26-2013 at 01:22 PM..
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