Did you already decide?

I didn't remove them. But I still want to know if I'm supposed to.

Unless someone else says otherwise I'm going with it was good to leave them on there just in case the plant can use it (functional) or reabsorb the resources in it (unfunctional).

I think sometimes when this happens, the outter covering of the root (I can't remember the proper term; please forgive me) gets pver saturated so melts away and the small thread is in a more proper environment since it's always moist buy had a little pillow of air around it, keeping it humid enough to be functional and where the part that had grown outside to the part where it was more exposed to air kept the covering and continued growing, because it's still connected. Even if it eventually dries up after the repot, the plant was able to evacuate as many of the stored resources as possible before the root died. That's the theory I'm going with until I receive information to the contrary lol.

The root is still functional. It lost its vellum coating. Sometimes it will grow a branch above the break in the vellum. The root looks alive and you can leave it.

Jane

Personally, I cut the root at the string when I see this when repotting phals. I don't think the lower portions are helpful to the mother plant as I can not see how it could move nutrients effectively through the string. It is my understanding that the vellum is what transports nutrients (???). I cut them because I feel they will die and rot causing more issues than benefits if left on the plant.

Nothing scientific, just my thoughts and observations from past experience.

Good luck,

Bob

I always thought the string part still functioned. I cut off the string if there's no vellium. I think the vellium catches the nutrients and the string part transports it to the plant. When all the vellium is gone, I cut the strings.

Who knows, just the way I've looked at it.

Jane

I was always of the understanding that the string transports water and nutrients (like a road) and the Velamen (this is the correct term, no such thing as "vellium" and "vellum" is something completely different, I had to look it up) is simply a protective layer to keep the living/vascular tissue hydrated and protected from damage kind of like how someone's skin/fat/bones protect the blood vessels in his or her body.

Anatomy of orchid roots: http://www.biologydiscussion.com/anatomy/anatomy-of-an-orchid-root-botany/56927

Edit: having more time to read the referenced text, it is fathoms more complicated than initially thought.

Kind of morbid, but.... I see it more as a "bone" being exposed. You want to cover it up (not possible with a 'chid) or cut it off above the problem before it causes more serious issues.

I didn't see/read what part of a root actually delivers the needed nutrients to the leaves or what part is the "string", maybe the pith? I googled around and couldn't find a definitive answer either???

Bob