Black spots on my dend

[NYCorchidman]

I have three white dendrobium hybirds. All of them are NOID, and all differ slightly in flower shape. Two of them are scream white with slight green cast with sweet scent in the morning and the other one is pure white with green center with no scent.

Anyhow, two of them have these black dots on the cane where the leaves attach to the cane.
They came that way when I got them.
I only post one picture, but the other plant has tons more black spots on it.

I have no idea what they are, but they sure look unsightly to me. They are dry, appear to be inside the tissues and not spreading in the past two months.

Any ideas???