Aerial Roots and Velamen - myth or fact?

[redperphexion]

Hi all. I've recently taken to putting damp sphagnum moss over the newest roots on my brand new mini-phal at work, and they're growing like mad, so I did the same with my normal phal at home last night... today I found this article about aerial roots:

Orchid Roots – Repotting | River Valley Orchidworks

I'm assuming that the new roots on my mini will be ok, since they're growing -into- this damp environment. I'm hoping, though that the moss over the roots on my normal phal will be able to hold more humidity in the media, as my apartment is really much too dry for an orchid - I was finding the top-most roots tend to be slightly wizened by the time watering day rolls around. (I have started running a humidifier in my little bachelor's, and repotted in a clay pot with lots of drainage sitting in a shallow dish of water (sort of minor s/h?).)

My question is, do you agree with this article, and do you think that a thin layer of damp sphag can damage aerial or semi-aerial roots? Do you think new roots can be "trained" one way or the other? Can old roots be gradually adjusted over long periods of time (I'm thinking of situtations like mounting, s/h, etc.) or not, and that's why we wait for 'new growth' before mounting or s/h, etc? (Wouldn't it be cool to gradually 'train' and orchid out of it's pot and onto it's mounting media? I suppose it would take years and years, though.)

Thanks in advance for your replies and suggestions!

[Ray]

I don't know that I specifically buy into the particular significance of the velamen layer, but I absolutely agree about being careful about moving roots accustomed to one environment into another.

As roots grow, they develop a cellular morphology that is "tailored" to the environment they are in. Once grown, the cells do not change. Change that environment - through repotting, in this discussion - and the existing cells may-, or may not function particularly well. That is why the timing of repotting is important, particularly when moving to an entirely different rot zone environment.

No, you cannot "train" roots to like a different environment, but that does not mean all is lost. I would imagine pretty much all of us have left a plant in an old, decomposing medium too long, and the result is partially-collapsing roots (that grew in a fresh medium environment, so cannot handle the current state). However, we've probably also seen new, healthy roots growing on the ends of those - they are "tailored" to that new (sour medium) environment - at least for a little while, until they succumb to the chemical stresses.